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  • 1.
    Aronson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Model-independent Exoplanet Transit Spectroscopy2018In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 155, no 5, article id 208Article in journal (Refereed)
    Abstract [en]

    We propose a new data analysis method for obtaining transmission spectra of exoplanet atmospheres and brightness variation across the stellar disk from transit observations. The new method is capable of recovering exoplanet atmosphere absorption spectra and stellar specific intensities without relying on theoretical models of stars and planets. We simultaneously fit both stellar specific intensity and planetary radius directly to transit light curves. This allows stellar models to be removed from the data analysis. Furthermore, we use a data quality weighted filtering technique to achieve an optimal trade-off between spectral resolution and reconstruction fidelity homogenizing the signal-to-noise ratio across the wavelength range. Such an approach is more efficient than conventional data binning onto a low-resolution wavelength grid. We demonstrate that our analysis is capable of reproducing results achieved by using an explicit quadratic limb-darkening equation and that the filtering technique helps eliminate spurious spectral features in regions with strong telluric absorption. The method is applied to the VLT FORS2 observations of the exoplanets GJ 1214 b and WASP-49 b, and our results are in agreement with previous studies. Comparisons between obtained stellar specific intensity and numerical models indicates that the method is capable of accurately reconstructing the specific intensity. The proposed method enables more robust characterization of exoplanetary atmospheres by separating derivation of planetary transmission and stellar specific intensity spectra (that is model-independent) from chemical and physical interpretation.

  • 2.
    Babu, Prabhu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Stoica, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Li, Jian
    Chen, Zhaofu
    Ge, Jian
    Analysis of radial velocity data by a novel adaptive approach2010In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 139, no 2, p. 783-793Article in journal (Refereed)
  • 3. Benedict, G. Fritz
    et al.
    McArthur, Barbara E.
    Feast, Michael W.
    Barnes, Thomas G.
    Harrison, Thomas E.
    Bean, Jacob L.
    Menzies, John W.
    Chaboyer, Brian
    Fossati, Luca
    Nesvacil, Nicole
    Smith, Horace A.
    Kolenberg, Katrien
    Laney, C. D.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Nelan, Edmund P.
    Shulyak, D. V.
    Taylor, Denise
    Freedman, Wendy L.
    Distance scale zero points from galactic RR Lyrae star parallaxes2011In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 142, no 6, p. 187-Article in journal (Refereed)
    Abstract [en]

    We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars-five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and kappa Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 +/- 0.16 mas; XZ Cyg, 1.67 +/- 0.17 mas; SU Dra, 1.42 +/- 0.16 mas; RR Lyr, 3.77 +/- 0.13 mas; UV Oct, 1.71 +/- 0.10 mas; VY Pyx, 6.44 +/- 0.23 mas; and. Pav, 5.57 +/- 0.28 mas; an average sigma(pi)/pi = 5.4%. With these parallaxes, we compute absolute magnitudes in V and K bandpasses corrected for interstellar extinction and Lutz-Kelker-Hanson bias. Using these RR Lyrae variable star absolute magnitudes, we then derive zero points for M(V)-[Fe/H] and M(K)-[Fe/H]-log P relations. The technique of reduced parallaxes corroborates these results. We employ our new results to determine distances and ages of several Galactic globular clusters and the distance of the Large Magellanic Cloud. The latter is close to that previously derived from Classical Cepheids uncorrected for any metallicity effect, indicating that any such effect is small. We also discuss the somewhat puzzling results obtained for our two type 2 Cepheids.

  • 4.
    Bodewits, D.
    et al.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;Akad Wissensch Gottingen, D-37077 Gottingen, Germany..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lin, Z. -Y
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Snodgrass, C.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Barucci, M. A.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, E-28691 Villanueva De La Canada, Madrid, Spain..
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland..
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, HU-1525 Budapest, Hungary..
    Vincent, J. -B
    Changes in the physical environment of the inner coma of 67p/churyumov-gerasimenko with decreasing heliocentric distance2016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 5, article id 130Article in journal (Refereed)
    Abstract [en]

    The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrow-band filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 and 1.3 au pre-perihelion. Our observations indicate that the emission observed in the OH, OI, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [OI] 630 nm emission. A strong plume-like feature observed in the CN and OI filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after 2015 March, which we attribute to decreased electron temperatures in the first few kilometers above the surface of the nucleus.

  • 5. Brown, Alexander
    et al.
    Neff, James E.
    Ayres, Thomas R.
    Kowalski, Adam
    Hawley, Suzanne
    Berdyugina, Svetlana
    Harper, Graham M.
    Korhonen, Heidi
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Saar, Steven
    Walkowicz, Lucianne
    Wells, Mark A.
    Serendipitous Discovery of a Dwarf Nova in the Kepler Field Near the G Dwarf Kic 54388452015In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 149, no 2, article id 67Article in journal (Refereed)
    Abstract [en]

    The Kepler satellite provides a unique window into stellar temporal variability by observing a wide variety of stars with multi-year, near-continuous, high precision, optical photometric time series. While most Kepler targets are faint stars with poorly known physical properties, many unexpected discoveries should result from a long photometric survey of such a large area of sky. During our Kepler Guest Observer programs that monitored late-type stars for starspot and flaring variability, we discovered a previously unknown dwarf nova that lies within a few arcseconds of the mid-G dwarf star KIC 5438845. This dwarf nova underwent nine outbursts over a 4 year time span. The two largest outbursts lasted similar to 17-18 days and show strong modulations with a 110.8 minute period and a declining amplitude during the outburst decay phase. These properties are characteristic of an SU UMa-type cataclysmic variable. By analogy with other dwarf nova light curves, we associate the 110.8 minute (1.847 hr) period with the superhump period, close to but slightly longer than the orbital period of the binary. No precursor outbursts are seen before the super-outbursts and the overall super-outburst morphology corresponds to Osaki & Meyer "Case B" outbursts, which are initiated when the outer edge of the disk reaches the tidal truncation radius. "Case B" outbursts are rare within the Kepler light curves of dwarf novae. The dwarf nova is undergoing relatively slow mass transfer, as evidenced by the long intervals between outbursts, but the mass transfer rate appears to be steady, because the smaller "normal" outbursts show a strong correlation between the integrated outburst energy and the elapsed time since the previous outburst. At super-outburst maximum the system was at V similar to 18, but in quiescence it is fainter than V similar to 22, which will make any detailed quiescent follow-up of this system difficult.

  • 6. De Silva, G. M.
    et al.
    Freeman, K. C.
    Asplund, M.
    Bland-Hawthorn, J.
    Bessell, M. S.
    Collet, Remo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Chemical homogeneity in collinder 261 and implications for chemical tagging2007In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 133, no 3, p. 1161-1175Article in journal (Refereed)
    Abstract [en]

    This paper presents abundances for 12 red giants of the old open cluster Collinder 261 based on spectra from the Very Large Telescope UVES. Abundances were derived for Na, Mg, Si, Ca, Mn, Fe, Ni, Zr, and Ba. We find that the cluster has a solar-level metallicity of [Fe/H] = -0.03 dex. However, most alpha- and s-process elements were found to be enhanced. The star-to-star scatter was consistent with the expected measurement uncertainty for all elements. The observed rms scatter is as follows: Na = 0.07, Mg = 0.05, Si = 0.06, Ca = 0.05, Mn = 0.03, Fe = 0.02, Ni = 0.04, Zr = 0.12, and Ba = 0.03 dex. The intrinsic scatter was estimated to be less than 0.05 dex. Such high levels of homogeneity indicate that chemical information remains preserved in this old open cluster. We use the chemical homogeneity we have now established in Cr 261, the Hyades, and the HR 1614 moving group to examine the uniqueness of the individual cluster abundance patterns, i.e., chemical signatures. We demonstrate that the three studied clusters have unique chemical signatures and discuss how other such signatures may be searched for in the future. Our findings support the prospect of chemically tagging disk stars to common formation sites in order to unravel the dissipative history of the Galactic disk.

  • 7.
    Edberg, Niklas J. T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vigren, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Goetz, Charlotte
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Braunschweig, Germany.
    Nilsson, Hans
    Swedish Inst Space Phys, POB 812, SE-98128 Kiruna, Sweden;Lulea Univ Technol, Dept Comp Sci Elect & Space Engn, Rymdcampus 1, SE-98128 Kiruna, Sweden.
    Gilet, Nicolas
    CNRS, LPC2E, Orleans, France.
    Henri, Pierre
    CNRS, LPC2E, Orleans, France.
    The Convective Electric Field Influence on the Cold Plasma and Diamagnetic Cavity of Comet 67P2019In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 158, no 2, article id 71Article in journal (Refereed)
    Abstract [en]

    We studied the distribution of cold electrons (<1 eV) around comet 67P/Churyumov-Gerasimenko with respect to the solar wind convective electric field direction. The cold plasma was measured by the Langmuir Probe instrument and the direction of the convective electric field E-conv = -nu x B was determined from magnetic field (B) measurements inside the coma combined with an assumption of a purely radial solar wind velocity nu. We found that the cold plasma is twice as likely to be observed when the convective electric field at Rosetta's position is directed toward the nucleus (in the -E(conv )hemisphere) compared to when it is away from the nucleus (in the +E-conv hemisphere). Similarly, the diamagnetic cavity, in which previous studies have shown that cold plasma is always present, was also found to be observed twice as often when in the -E-conv hemisphere, linking its existence circumstantially to the presence of cold electrons. The results are consistent with hybrid and Hall magnetohydrodynamic simulations as well as measurements of the ion distribution around the diamagnetic cavity.

  • 8.
    Gonzalez, Carlos Alberto Gomez
    et al.
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.
    Wertz, Olivier
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.
    Absil, Olivier
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.
    Christiaens, Valentin
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.; Univ Chile, Dept Astron, Santiago, Chile.; Millennium Nucleus Protoplanetary Disks, Santiago, Chile.
    Defrère, Denis
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.
    Mawet, Dimitri
    CALTECH, Dept Astron, Pasadena, CA 91125 USA.; Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA.
    Milli, Julien
    European Southern Observ, Santiago, Chile.
    Absil, Pierre-Antoine
    Catholic Univ Louvain, Dept Math Engn, B-1348 Louvain La Neuve, Belgium.
    Van Droogenbroeck, Marc
    Univ Liege, Inst Montefiore, B-4000 Liege, Belgium.
    Cantalloube, Faustine
    CNRS, IPAG, F-38000 Grenoble, France.; Off Natl Etud & Rech Aerosp, Opt Dept, BP 72, F-92322 Chatillon, France.
    Hinz, Philip
    Univ Arizona, Dept Astron, Steward Observ, 933 N Cherry Ave, Tucson, AZ 85721 USA.
    Skemer, Andrew
    Univ Calif Santa Cruz, 1156 High St, Santa Cruz, CA 95064 USA.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Surdej, Jean
    Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee Six Aout 19c, B-4000 Liege, Belgium.
    VIP: Vortex Image Processing Package for High-contrast Direct Imaging2017In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 154, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    We present the Vortex Image Processing (VIP) library, a python package dedicated to astronomical high-contrast imaging. Our package relies on the extensive python stack of scientific libraries and aims to provide a flexible framework for high-contrast data and image processing. In this paper, we describe the capabilities of VIP related to processing image sequences acquired using the angular differential imaging (ADI) observing technique. VIP implements functionalities for building high-contrast data processing pipelines, encompassing pre- and post-processing algorithms, potential source. position and flux estimation, and sensitivity curve. generation. Among the reference point-spread. function subtraction techniques for ADI post-processing, VIP includes several flavors of principal component analysis (PCA) based algorithms, such as annular PCA and incremental PCA algorithms capable of processing big datacubes (of several gigabytes) on a computer with limited memory. Also, we present a novel ADI algorithm based on non-negative matrix factorization, which comes from the same family of low-rank matrix approximations as PCA and provides fairly similar results. We showcase the ADI capabilities of the VIP library using a deep sequence on HR 8799 taken with the LBTI/LMIRCam and its recently commissioned L-band vortex coronagraph. Using VIP, we investigated the presence of additional companions around HR 8799 and did not find any significant additional point source beyond the four known planets. VIP is available at http://github. com/vortex-exoplanet/VIP and is accompanied with Jupyter notebook tutorials illustrating the main functionalities of the library.

  • 9.
    Holtzman, Jon A.
    et al.
    New Mexico State Univ, Las Cruces, NM, USA.
    Hasselquist, Sten
    New Mexico State Univ, Las Cruces, NM, USA; Univ Utah, Salt Lake City, UT, USA.
    Shetrone, Matthew
    Univ Texas Austin, McDonald Observ, Ft Davis, TX, USA.
    Cunha, Katia
    Observ Nacl, Sao Cristovao, RJ, Brazil; Univ Arizona, Tucson, AZ, USA.
    Allende Prieto, Carlos
    Inst Astrofis Canarias, Tenerife, Spain; Univ La Laguna, Dept Astrofis, Tenerife, Spain.
    Anguiano, Borja
    Univ Virginia, Dept Astron, Charlottesville, VA, USA; Macquarie Univ, Dept Phys & Astron, Balaclava Rd, N Ryde, NSW, Australia.
    Bizyaev, Dmitry
    Apache Point Observ, Sunspot, NM USA; Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow, Russia.
    Bovy, Jo
    Univ Toronto, Dept Astron & Astrophys, Toronto, ON, Canada; Univ Toronto, Dunlap Inst Astron & Astrophys, Toronto, ON, Canada.
    Casey, Andrew
    Monash Univ, Sch Phys & Astron, Clayton, Australia; Monash Univ, Fac Informat Technol, Clayton, Australia.
    Edvardsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Johnson, Jennifer A.
    Ohio State Univ, Dept Astron, Columbus, OH, USA.
    Jonsson, Henrik
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Lund, Sweden.
    Meszaros, Szabolcs
    Eotvos Lorand Univ, Gothard Astrophys Observ, Szombathely, Hungary; Hungarian Acad Sci, Budapest, Hungary.
    Smith, Verne V.
    Natl Opt Astron Observ, Tucson, AZ, USA.
    Sobeck, Jennifer
    Univ Washington, Dept Astron, Seattle, WA, USA.
    Zamora, Olga
    Inst Astrofis Canarias, Tenerife, Spain; Univ La Laguna, Dept Astrofis, Tenerife, Spain.
    Chojnowski, S. Drew
    New Mexico State Univ, Las Cruces, NM, USA.
    Fernandez-Trincado, Jose
    Univ Bourgogne Franche Comte, Observ Besancon, CNRS, Inst Utinam, OSU THETA, UMR6213, Besancon, France; Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion, Chile.
    Garcia Hernandez, Anibal
    Inst Astrofis Canarias, Tenerife, Spain; Univ La Laguna, Dept Astrofis, Tenerife, Spain.
    Majewski, Steven R.
    Univ Virginia, Dept Astron, Charlottesville, VA, USA.
    Pinsonneault, Marc
    Ohio State Univ, Dept Astron, Columbus, OH, USA.
    Souto, Diogo
    Observ Nacl, Sao Cristovao, RJ, Brazil.
    Stringfellow, Guy S.
    Univ Colorado, Ctr Astrophys & Space Astron, Dept Astrophys & Planetary Sci, Boulder, CO, USA.
    Tayar, Jamie
    Ohio State Univ, Dept Astron, Columbus, OH, USA.
    Troup, Nicholas
    Salisbury Univ, Dept Phys, Salisbury, MD, USA.
    Zasowski, Gail
    Univ Utah, Salt Lake City, UT, USA.
    APOGEE Data Releases 13 and 14: Data and Analysis2018In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 156, no 3, article id 125Article in journal (Refereed)
    Abstract [en]

    The data and analysis methodology used for the SDSS/APOGEE Data Releases 13 and 14 are described, highlighting differences from the DR12 analysis presented in Holtzman et al. Some improvement in the handling of telluric absorption and persistence is demonstrated. The derivation and calibration of stellar parameters, chemical abundances, and respective uncertainties are described, along with the ranges over which calibration was performed. Some known issues with the public data related to the calibration of the effective temperatures (DR13), surface gravity (DR13 and DR14), and C and N abundances for dwarfs (DR13 and DR14) are highlighted. We discuss how results from a data-driven technique, The Cannon, are included in DR14 and compare those with results from the APOGEE Stellar Parameters and Chemical Abundances Pipeline. We describe how using The Cannon in a mode that restricts the abundance analysis of each element to regions of the spectrum with known features from that element leads to Cannon abundances can lead to significantly different results for some elements than when all regions of the spectrum are used to derive abundances.

  • 10.
    Luck, R. Earle
    et al.
    Department of Astronomy, Case Western Reserve University, Cleveland.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Giants in the Local Region2007In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 133, no 6, p. 2464-2486Article in journal (Refereed)
    Abstract [en]

    We present parameter and abundance data for a sample of 298 nearby giants. The spectroscopic data for this work have a resolution of R~60,000, S/N>150, and spectral coverage from 475 to 685 nm. Overall trends in the Z>10 abundances are dominated by Galactic chemical evolution, while the light-element abundances are influenced by stellar evolution, as well as Galactic evolution. We find several super-Li stars in our sample and confirm that Li abundances in the first giant branch are related to mixing depths. Once astration of lithium on the main sequence along with the overall range of main-sequence lithium abundances are taken into account, the lithium abundances of the giants are not dramatically at odds with the predictions of standard stellar evolution. We find the giants to be carbon-diluted in accord with standard stellar evolution and that the carbon and oxygen abundances determined for the local giants are consistent with those found in local field dwarfs. We find that there is evidence for systematic carbon variations in the red giant clump in the sense that the blue side of the clump is carbon-poor (more diluted) than the red side.

  • 11.
    Mann, Andrew W.
    et al.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Newton, Elisabeth R.
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Rizzuto, Aaron C.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Irwin, Jonathan
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Feiden, Gregory
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Gaidos, Eric
    Univ Hawaii Manoa, Dept Geol & Geophys, Honolulu, HI 96822 USA..
    Mace, Gregory N.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Kraus, Adam L.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    James, David J.
    Cerro Tololo Interamer Observ, Colina El Pino, Laserena, Chile..
    Ansdell, Megan
    Univ Hawaii Manoa, Inst Astron, Honolulu, HI 96822 USA..
    Charbonneau, David
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Covey, Kevin R.
    Western Washington Univ, Dept Phys & Astron, Bellingham, WA 98225 USA..
    Ireland, Michael J.
    Australia Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia..
    Jaffe, Daniel T.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Johnson, Marshall C.
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Kidder, Benjamin
    Univ Texas Austin, Dept Astron, Austin, TX 78712 USA..
    Vanderburg, Andrew
    Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA..
    Zodiacal Exoplanets In Time (Zeit). III. A Short-Period Planet Orbiting A Pre-Main-Sequence Star In The Upper Scorpius Ob Association2016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 3, article id 61Article in journal (Refereed)
    Abstract [en]

    We confirm and characterize a close-in (P-orb = 5.425 days), super-Neptune sized (5.04(-0.37)(+0.34) R-circle plus) planet transiting K2-33 (2MASS J16101473-1919095), a late-type (M3) pre-main-sequence (11 Myr old) star in the Upper Scorpius subgroup of the Scorpius-Centaurus OB association. The host star has the kinematics of a member of the Upper Scorpius OB association, and its spectrum contains lithium absorption, an unambiguous sign of youth (<20 Myr) in late-type dwarfs. We combine photometry from K2 and the ground-based MEarth project to refine the planet's properties and constrain the host star's density. We determine K2-33's bolometric flux and effective temperature from moderate-resolution spectra. By utilizing isochrones that include the effects of magnetic fields, we derive a precise radius (6%-7%) and mass (16%) for the host star, and a stellar age consistent with the established value for Upper Scorpius. Follow-up high-resolution imaging and Doppler spectroscopy confirm that the transiting object is not a stellar companion or a background eclipsing binary blended with the target. The shape of the transit, the constancy of the transit depth and periodicity over 1.5 yr, and the independence with wavelength rule out stellar variability or a dust cloud or debris disk partially occulting the star as the source of the signal; we conclude that it must instead be planetary in origin. The existence of K2-33b suggests that close-in planets can form in situ or migrate within similar to 10 Myr, e.g., via interactions with a disk, and that long-timescale dynamical migration such as by Lidov-Kozai or planet-planet scattering is not responsible for all short-period planets.

  • 12.
    Mawet, Dimitri
    et al.
    California Institute of Technology/Jet Propulsion Laboratory (NASA), USA.
    Choquet, Élodie
    Jet Propulsion Laboratory (NASA), USA.
    Absil, Olivier
    Université de Liège, Belgium.
    Huby, Elsa
    Université de Liège, Belgium.
    Bottom, Michael
    California Institute of Technology/Jet Propulsion Laboratory (NASA), USA.
    Serabyn, Eugene
    Jet Propulsion Laboratory (NASA), USA.
    Femenia, Bruno
    W. M. Keck Observatory, USA.
    Lebreton, Jérémy
    NASA Exoplanet Science Institute, California Institute of Technology, USA.
    Matthews, Keith
    California Institute of Technology, USA.
    Gomez Gonzalez, Carlos A.
    Université de Liège, Belgium.
    Wertz, Olivier
    Argelander-Institut fur Astronomie, Germany.
    Carlomagno, Brunella
    Université de Liège, Belgium.
    Christiaens, Valentin
    Universidad de Chile, Chile.
    Defrére, Denis
    University of Arizona, USA.
    Delacroix, Christian
    Cornell University, USA.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Habraken, Serge
    Université de Liège, Belgium.
    Jolivet, Aissa
    Université de Liège, Belgium.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Milli, Julien
    European Southern Observatory, Chile.
    Pinte, Christophe
    Univ. Grenoble Alpes, France.
    Piron, Pierre
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Reggiani, Maddalena
    Université de Liège, Belgium.
    Surdej, Jean
    Université de Liège, Belgium.
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Characterization of the inner disk around HD 141569 A from KECK/NIRC2 L-band vortex coronagraphy2017In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 153, no 1, p. 1-10, article id 44Article in journal (Refereed)
    Abstract [en]

    HD 141569 A is a pre-main sequence B9.5 Ve star surrounded by a prominent and complex circumstellar disk, likely still in a transition stage from protoplanetary to debris disk phase. Here, we present a new image of the third inner disk component of HD 141569 A made in the L′ band (3.8 μm) during the commissioning of the vector vortex coronagraph that has recently been installed in the near-infrared imager and spectrograph NIRC2 behind the W. M. Keck Observatory Keck II adaptive optics system. We used reference point-spread function subtraction, which reveals the innermost disk component from the inner working distance of ;23 au and up to ;70 au. The spatial scale of our detection roughly corresponds to the optical and near-infrared scattered light, thermal Q, N, and 8.6 μm PAH emission reported earlier. We also see an outward progression in dust location from the L′ band to the H  band (Very Large Telescope/ SPHERE image)  to the visible (Hubble Space Telescope (HST)/ STIS image), which is likely indicative of dust blowout. The warm disk component is nested deep inside the two outer belts imaged by HST-NICMOS in 1999 ( at 406 and 245 au, respectively) . We fit our new L′ -band image and spectral energy distribution of HD 141569 A with the radiative transfer code MCFOST. Our best-fit models favor pure olivine grains and are consistent with the composition of the outer belts. While our image shows a putative very faint point-like clump or source embedded in the inner disk, we did not detect any true companion within the gap between the inner disk and the first outer ring, at a sensitivity of a few Jupiter masses.

  • 13. Meszaros, Sz.
    et al.
    Allende Prieto, C.
    Edvardsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Castelli, F.
    Perez, A. E. Garcia
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Majewski, S. R.
    Plez, B.
    Schiavon, R.
    Shetrone, M.
    de Vicente, A.
    New ATLAS9 and MARCS Model Atmosphere Grids for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)2012In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 144, no 4, p. 120-Article in journal (Refereed)
    Abstract [en]

    We present a new grid of model photospheres for the SDSS-III/APOGEE survey of stellar populations of the Galaxy, calculated using the ATLAS9 and MARCS codes. New opacity distribution functions were generated to calculate ATLAS9 model photospheres. MARCS models were calculated based on opacity sampling techniques. The metallicity ([M/H]) spans from -5 to 1.5 for ATLAS and -2.5 to 0.5 for MARCS models. There are three main differences with respect to previous ATLAS9 model grids: a new corrected H2O line list, a wide range of carbon ([C/M]) and alpha element [alpha/M] variations, and solar reference abundances from Asplund et al. The added range of varying carbon and alpha-element abundances also extends the previously calculated MARCS model grids. Altogether, 1980 chemical compositions were used for the ATLAS9 grid and 175 for the MARCS grid. Over 808,000 ATLAS9 models were computed spanning temperatures from 3500 K to 30,000 K and log g from 0 to 5, where larger temperatures only have high gravities. The MARCS models span from 3500 K to 5500 K, and log g from 0 to 5. All model atmospheres are publicly available online.

  • 14. Mottola, Stefano
    et al.
    Di Martino, Mario
    Erikson, Anders
    Gonano-Beurer, Maria
    Carbognani, Albino
    Carsenty, Uri
    Hahn, Gerhard
    Schober, Hans-Josef
    Lahulla, Felix
    Delbo, Marco
    Lagerkvist, Claes-Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rotational Properties of Jupiter Trojans. I. Light Curves of 80 Objects2011In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 141, no 5, p. 170-Article in journal (Refereed)
    Abstract [en]

    We present the results of a Jupiter Trojans' light curve survey aimed at characterizing the rotational properties of Trojans in the approximate size range 60-150 km. The survey, which was designed to provide reliable and unbiased estimates of rotation periods and amplitudes, resulted in light curves for a total of 80 objects, 56 of which represent the first determinations published to date and nine of which supersede previously published erroneous values. Our results more than double the size of the existing database of rotational properties of Jovian Trojans in the selected size range. The analysis of the distributions of the rotation periods and light curve amplitudes is the subject of companion papers.

  • 15.
    Noonan, John W.
    et al.
    Southwest Res Inst, Dept Space Studies, Suite 300,1050 Walnut St, Boulder, CO 80302 USA;Univ Arizona, Lunar & Planetary Lab, 1629 E Univ Blvd, Tucson, AZ 85721 USA.
    Stern, S. Alan
    Southwest Res Inst, Dept Space Studies, Suite 300,1050 Walnut St, Boulder, CO 80302 USA.
    Feldman, Paul D.
    Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA.
    Broiles, Thomas
    Space Sci Inst, 4750 Walnut St,Suite 205, Boulder, CO 80301 USA.
    Wedlund, Cyril Simon
    Univ Oslo, Dept Phys, Box 1048 Blindern, N-0316 Oslo, Norway.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Schindhelm, Eric
    Ball Aerosp & Technol Corp, 1600 Commerce St, Boulder, CO 80301 USA.
    Parker, Joel Wm
    Southwest Res Inst, Dept Space Studies, Suite 300,1050 Walnut St, Boulder, CO 80302 USA.
    Keeney, Brian A.
    Southwest Res Inst, Dept Space Studies, Suite 300,1050 Walnut St, Boulder, CO 80302 USA.
    Vervack, Ronald J., Jr.
    Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA.
    Steffl, Andrew J.
    Southwest Res Inst, Dept Space Studies, Suite 300,1050 Walnut St, Boulder, CO 80302 USA.
    Knight, Matthew M.
    Univ Maryland, Astron Dept, College Pk, MD 20742 USA.
    Weaver, Harold A.
    Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA.
    Feaga, Lori M.
    Univ Maryland, Astron Dept, College Pk, MD 20742 USA.
    A'Hearn, Michael
    Univ Maryland, Astron Dept, College Pk, MD 20742 USA.
    Bertaux, Jean-Loup
    CNRS UVSQ IPSL, LATMOS, 11 Blvd Alembert, F-78280 Guyancourt, France.
    Ultraviolet Observations of Coronal Mass Ejection Impact on Comet 67P/Churyumov-Gerasimenko by Rosetta Alice2018In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 156, no 1, article id 16Article in journal (Refereed)
    Abstract [en]

    The Alice ultraviolet spectrograph on the European Space Agency Rosetta spacecraft observed comet 67P/Churyumov-Gerasimenko in its orbit around the Sun for just over two years. Alice observations taken in 2015 October, two months after perihelion, show large increases in the comet's Ly beta, OI 1304, OI 1356, and CI 1657 angstrom atomic emission that initially appeared to indicate gaseous outbursts. However, the Rosetta Plasma Consortium instruments showed a coronal mass ejection (CME) impact at the comet coincident with the emission increases, suggesting that the CME impact may have been the cause of the increased emission. The presence of the semi-forbidden OI 1356 angstrom emission multiplet is indicative of a substantial increase in dissociative electron impact emission from the coma, suggesting a change in the electron population during the CME impact. The increase in dissociative electron impact could be a result of the interaction between the CME and the coma of 67P or an outburst coincident with the arrival of the CME. The observed dissociative electron impact emission during this period is used to characterize the O-2 content of the coma at two peaks during the CME arrival. The mechanism that could cause the relationship between the CME and UV emission brightness is not well constrained, but we present several hypotheses to explain the correlation.

  • 16.
    Pardy, Stephen A.
    et al.
    Univ Wisconsin, Dept Astron, 475 North Charter St, Madison, WI 53706 USA..
    Cannon, John M.
    Macalester Coll, Dept Phys & Astron, 1600 Grand Ave, St Paul, MN 55105 USA..
    Östlin, Göran
    Stockholm Univ, Oskar Klein Ctr, Dept Astron, AlbaNova Univ Ctr, SE-10691 Stockholm, Sweden..
    Hayes, Matthew
    Stockholm Univ, Oskar Klein Ctr, Dept Astron, AlbaNova Univ Ctr, SE-10691 Stockholm, Sweden..
    Bergvall, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Detection Of H I In Emission In The LY Alpha Emitting Galaxy Haro 112016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 6, article id 178Article in journal (Refereed)
    Abstract [en]

    We present the first robust detection of H I 21 cm emission in the blue compact galaxy Haro 11 using the 100 m Robert C. Byrd Green Bank Telescope (GBT). Haro 11 is a luminous blue compact galaxy with emission in both Ly alpha and the Lyman continuum. We detect (5.1 +/- 0.7 x 10(8)) M-circle dot of H I gas at an assumed distance of 88 Mpc, making this galaxy H I deficient compared to other local galaxies with similar optical properties. Given this small H I mass, Haro 11 has an elevated MH2/MH I ratio and a very low gas fraction compared to most local galaxies, and contains twice as much mass in ionized hydrogen as in neutral hydrogen. The H I emission has a linewidth of 71 km s(-1) and is offset 60 km s(-1) redward of the optical line center. It is undergoing a starburst after a recent merger that has elevated the star formation rate, and will deplete the gas supply in <0.2 Gyr. Although this starburst has elevated the star formation rate (SFR) compared to galaxies with similar H I masses and line widths, Haro 11 matches a trend of lower gas fractions toward higher SFRs and is below the general trend of increasing H I mass with increasing luminosity. Taken together, our results paint Haro 11 as a standard low-mass galaxy that is undergoing an unusually efficient star formation episode.

  • 17.
    Serabyn, E
    et al.
    Jet Propulsion Laboratory (NASA), USA.
    Huby, E
    Université de Liège, Belgium.
    Matthews, K
    California Institute of Technology, USA.
    Mawet, D
    California Institute of Technology, USA.
    Absil, O
    Université de Liège, Belgium.
    Femenia, B
    W. M. Keck Observatory, USA.
    Wizinowich, P
    W. M. Keck Observatory, USA.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Bottom, M
    California Institute of Technology, USA.
    Campbell, R
    W. M. Keck Observatory, USA.
    Carlomagno, B
    Université de Liège, Belgium.
    Defrère, D
    Université de Liège, Belgium.
    Delacroix, C
    Université de Liège, Belgium.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gomez Gonzalez, C
    Université de Liège, Belgium.
    Habraken, S
    Université de Liège, Belgium.
    Jolivet, A
    Université de Liège, Belgium.
    Liewer, K
    Jet Propulsion Laboratory (NASA), USA.
    Lilley, S
    W. M. Keck Observatory, USA.
    Piron, Pierre
    Université de Liège, Belgium.
    Reggiani, M
    Université de Liège, Belgium.
    Surdej, J
    Université de Liège, Belgium.
    Tran, H
    W. M. Keck Observatory, USA.
    Vargas Catalan, Ernesto
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wertz, O
    Université de Liège, Belgium.
    The W. M. Keck Observatory infrared vortex coronagraph and a first image of HIP79124 B2017In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 153, no 1, p. 1-7, article id 43Article in journal (Refereed)
    Abstract [en]

    An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L′-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP 79124, which had previously been detected by means of interferometry. With HIP 79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Due to higher Strehl ratios and more relaxed contrasts in L′ band versus H band, this new coronagraphic capability will enable high-contrast, small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs.

  • 18. Simpson, E. K.
    et al.
    Barros, S. C. C.
    Brown, D. J. A.
    Cameron, A. Collier
    Pollacco, D.
    Skillen, I.
    Stempels, Henricus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Boisse, I.
    Faedi, F.
    Hebrard, G.
    McCormac, J.
    Sorensen, P.
    Street, R. A.
    Anderson, D.
    Bento, J.
    Bouchy, F.
    Butters, O. W.
    Enoch, B.
    Haswell, C. A.
    Hebb, L.
    Hellier, C.
    Holmes, S.
    Horne, K.
    Keenan, F. P.
    Lister, T. A.
    Maxted, P. F. L.
    Miller, G. R. M.
    Moulds, V.
    Moutou, C.
    Norton, A. J.
    Parley, N.
    Santerne, A.
    Smalley, B.
    Smith, A. M. S.
    Todd, I.
    Watson, C. A.
    West, R. G.
    Wheatley, P. J.
    Independent Discovery of the Transiting Exoplanet HAT-P-14b2011In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 141, no 5, p. 161-Article in journal (Refereed)
    Abstract [en]

    We present SuperWASP observations of HAT-P-14b, a hot Jupiter discovered by Torres et al. The planet was found independently by the SuperWASP team and named WASP-27b after follow-up observations had secured the discovery, but prior to the publication by Torres et al. Our analysis of HAT-P-14/WASP-27 is in good agreement with the values found by Torres et al. and we provide additional evidence against astronomical false positives. Due to the brightness of the host star, V-mag = 10, HAT-P-14b is an attractive candidate for further characterization observations. The planet has a high impact parameter and the primary transit is close to grazing. This could readily reveal small deviations in the orbital parameters indicating the presence of a third body in the system, which may be causing the small but significant orbital eccentricity. Our results suggest that the planet may undergo a grazing secondary eclipse. However, even a non-detection would tightly constrain the system parameters.

  • 19. Simpson, E. K.
    et al.
    Faedi, F.
    Barros, S. C. C.
    Brown, D. J. A.
    Cameron, A. Collier
    Hebb, L.
    Pollacco, D.
    Smalley, B.
    Todd, I.
    Butters, O. W.
    Hebrard, G.
    McCormac, J.
    Miller, G. R. M.
    Santerne, A.
    Street, R. A.
    Skillen, I.
    Triaud, A. H. M. J.
    Anderson, D. R.
    Bento, J.
    Boisse, I.
    Bouchy, F.
    Enoch, B.
    Haswell, C. A.
    Hellier, C.
    Holmes, S.
    Horne, K.
    Keenan, F. P.
    Lister, T. A.
    Maxted, P. F. L.
    Moulds, V.
    Moutou, C.
    Norton, A. J.
    Parley, N.
    Pepe, F.
    Queloz, D.
    Segransan, D.
    Smith, A. M. S.
    Stempels, H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Udry, S.
    Watson, C. A.
    West, R. G.
    Wheatley, P. J.
    WASP-37b: A 1.8 MJ exoplanet transiting a metal-poor star2011In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 141, no 1, p. 8-Article in journal (Refereed)
    Abstract [en]

    We report on the discovery of WASP-37b, a transiting hot Jupiter orbiting an m(v) = 12.7 G2-type dwarf, with a period of 3.577469 +/- 0.000011 d, transit epoch T-0 = 2455338.6188 +/- 0.0006 (HJD; dates throughout the paper are given in Coordinated Universal Time (UTC)), and a transit duration 0.1304(-0.0017)(+0.0018) d. The planetary companion has a mass M-p = 1.80 +/- 0.17 M-J and radius R-p = 1.16(-0.06)(+0.07) R-J, yielding a mean density of 1.15(-0.15)(+0.12) rho(J). From a spectral analysis, we find that the host star has M-star = 0.925 +/- 0.120 M-circle dot, R-star = 1.003 +/- 0.053 R-circle dot, T-eff = 5800 +/- 150 K, and [Fe/H] = -0.40 +/- 0.12. WASP-37 is therefore one of the lowest metallicity stars to host a transiting planet.

  • 20.
    Vigren, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Altwegg, K.
    Univ Bern, Inst Phys, Bern, Switzerland..
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders. I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Galand, M.
    Imperial Coll London, Dept Phys, London, England..
    Henri, P.
    Lab Phys & Chim Environm & Espace, Orleans, France..
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. Lab Phys & Chim Environm & Espace, Orleans, France..
    Odelstad, Elias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Tzou, C. -Y
    Vallieres, X.
    Lab Phys & Chim Environm & Espace, Orleans, France..
    Model-Observation Comparisons Of Electron Number Densities In The Coma Of 67P/Churyumov-Gerasimenko During 2015 January2016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 3, article id 59Article in journal (Refereed)
    Abstract [en]

    During 2015 January 9-11, at a heliocentric distance of similar to 2.58-2.57 au, the ESA Rosetta spacecraft resided at a cometocentric distance of similar to 28 km from the nucleus of comet 67P/Churyumov-Gerasimenko, sweeping the terminator at northern latitudes of 43 degrees N-58 degrees N. Measurements by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Comet Pressure Sensor (ROSINA/COPS) provided neutral number densities. We have computed modeled electron number densities using the neutral number densities as input into a Field Free Chemistry Free model, assuming H2O dominance and ion-electron pair formation by photoionization only. A good agreement (typically within 25%) is found between the modeled electron number densities and those observed from measurements by the Mutual Impedance Probe (RPC/MIP) and the Langmuir Probe (RPC/LAP), both being subsystems of the Rosetta Plasma Consortium. This indicates that ions along the nucleus-spacecraft line were strongly coupled to the neutrals, moving radially outward with about the same speed. Such a statement, we propose, can be further tested by observations of H3O+/H2O+ number density ratios and associated comparisons with model results.

  • 21.
    Vigren, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    A 1D Model of Radial Ion Motion Interrupted by Ion-Neutral Interactions in a Cometary Coma2017In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 153, no 4, article id 150Article in journal (Refereed)
    Abstract [en]

    Because ion- neutral reaction cross sections are energy dependent, the distance from a cometary nucleus within which ions remain collisionally coupled to the neutrals is dictated not only by the comet's activity level but also by the electromagnetic fields in the coma. Here we present a 1D model simulating the outward radial motion of water group ions with radial acceleration by an ambipolar electric field interrupted primarily by charge transfer processes with H2O. We also discuss the impact of plasma waves. For a given electric field profile, the model calculates key parameters, including the total ion density, n(I), the H3O+/H2O+ number density and flux ratios, R-dens and R-flux, and the mean ion drift speed, < u(I)>, as a function of cometocentric distance. We focus primarily on a coma roughly resembling that of the ESA Rosetta mission target comet 67P/Churyumov-Gerasimenko near its perihelion in 2015 August. In the presence of a weak ambipolar electric field in the radial direction the model results suggest that the neutral coma is not sufficiently dense to keep the mean ion flow speed close to that of the neutrals by the spacecraft location (similar to 200 km from the nucleus). In addition, for electric field profiles giving nI and < u(I)> within limits constrained by measurements, the Rdens values are significantly higher than values typically observed. However, when including the ion motion in large-amplitude plasma waves in the model, results more compatible with observations are obtained. We suggest that the variable and often low H3O+/H2O+ number density ratios observed may reflect nonradial ion trajectories strongly influenced by electromagnetic forces and/or plasma instabilities, with energization of the ion population by plasma waves.

  • 22.
    Villarroel Rodriguez, Beatriz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Imaz, Inigo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Bergstedt, Josefine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Our Sky Now And Then: Searches For Lost Stars And Impossible Effects As Probes Of Advanced Extraterrestrial Civilizations2016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 3, article id 76Article in journal (Refereed)
    Abstract [en]

    Searches for extraterrestrial intelligence using large survey data often look for possible signatures of astroengineering. We propose searching for physically impossible effects caused by highly advanced technology by carrying out a search for disappearing galaxies and Milky Way stars. We select similar to 10 million objects from USNO-B1.0 with low proper motions (mu < 20 mas yr(-1)) imaged on the sky in two epochs. We search for objects not found at the expected positions in the Sloan Digital Sky Survey (SDSS) by visually examining images of similar to 290,000 USNO-B1.0 objects with no counterpart in the SDSS. We identify some spurious targets in the USNO-B1.0. We find one candidate of interest for follow-up photometry, although it is very uncertain. If the candidate eventually is found, it defines the probability of observing a disappearing-object event in the last decade to less than one in one million in the given samples. Nevertheless, because the complete USNO-B1.0 data. set is 100 times larger than any of our samples, we propose an easily accessible citizen science project in search of USNO-B1.0 objects that have disappeared from the SDSS.

  • 23.
    Wittenmyer, Robert A.
    et al.
    Univ Southern Queensland, Computat Engn & Sci Res Ctr, Toowoomba, Qld 4350, Australia.;Univ New South Wales, Australian Ctr Astrobiol, Sydney, NSW 2052, Australia..
    Sharma, Sanjib
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Stello, Dennis
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia.;Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia.;Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, DK-8000 Aarhus C, Denmark..
    Buder, Sven
    MPIA, Koenigstuhl 17, D-69117 Heidelberg, Germany.;Heidelberg Univ, Int Max Planck Res Sch Astron Cosm Phys, Heidelberg, Germany..
    Kos, Janez
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Asplund, Martin
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Duong, Ly
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Lin, Jane
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Lind, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. MPIA, Koenigstuhl 17, D-69117 Heidelberg, Germany.
    Ness, Melissa
    MPIA, Koenigstuhl 17, D-69117 Heidelberg, Germany..
    Zwitter, Tomaz
    Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia..
    Horner, Jonathan
    Univ Southern Queensland, Computat Engn & Sci Res Ctr, Toowoomba, Qld 4350, Australia..
    Clark, Jake
    Univ Southern Queensland, Computat Engn & Sci Res Ctr, Toowoomba, Qld 4350, Australia..
    Kane, Stephen R.
    Univ Calif Riverside, Dept Earth Sci, Riverside, CA 92521 USA..
    Huber, Daniel
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia.;Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA.;SETI Inst, 189 Bernardo Ave, Mountain View, CA 94043 USA.;Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.;Australian Astron Observ, 105 Delhi Rd, N Ryde, NSW 2113, Australia.;Macquarie Univ, Dept Phys & Astron, Sydney, NSW 2109, Australia..
    Bland-Hawthorn, Joss
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Casey, Andrew R.
    Monash Univ, Sch Phys & Astron, Monash Ctr Astrophys, Clayton, Vic 3800, Australia..
    De Silva, Gayandhi M.
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia.;Australian Astron Observ, 105 Delhi Rd, N Ryde, NSW 2113, Australia..
    D'Orazi, Valentina
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Freeman, Ken
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia..
    Martell, Sarah
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia..
    Simpson, Jeffrey D.
    Australian Astron Observ, 105 Delhi Rd, N Ryde, NSW 2113, Australia..
    Zucker, Daniel B.
    Macquarie Univ, Res Ctr Astron Astrophys & Astrophoton, Sydney, NSW 2109, Australia..
    Anguiano, Borja
    Macquarie Univ, Dept Phys & Astron, Sydney, NSW 2109, Australia.;Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA..
    Casagrande, Luca
    Australian Natl Univ, Res Sch Astron & Astrophys, Cotter Rd, Weston, ACT 2611, Australia..
    Esdaile, James
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia..
    Hon, Marc
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia..
    Ireland, Michael
    Australian Natl Univ, Res Sch Astron & Astrophys, Cotter Rd, Weston, ACT 2611, Australia..
    Kafle, Prajwal R.
    Univ Western Australia, ICRAR, 35 Stirling Highway, Crawley, WA 6009, Australia..
    Khanna, Shourya
    Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Marshall, J. P.
    Acad Sinica, Inst Astron & Astrophys, Taipei 10617, Taiwan..
    Saddon, Mohd Hafiz Mohd
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia..
    Traven, Gregor
    Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia..
    Wright, Duncan
    Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia.;Australian Astron Observ, 105 Delhi Rd, N Ryde, NSW 2113, Australia..
    The K2-HERMES Survey. I. Planet-candidate Properties from K2 Campaigns 1-32018In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 155, no 2, article id 84Article in journal (Refereed)
    Abstract [en]

    Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present first results from the K2-HERMES project, which uses the HERMES multi-object spectrograph on the Anglo-Australian Telescope to obtain R similar to 28000 spectra of up to 360 stars in one exposure. This ongoing project aims to derive self-consistent spectroscopic parameters for about half of K2 target stars. We present complete stellar parameters and isochrone-derived masses and radii for 46 stars hosting 57 K2 candidate planets in Campaigns 1-3. Our revised host-star radii cast severe doubt on three candidate planets: EPIC 201407812.01, EPIC 203070421.01, and EPIC 202843107.01, all of which now have inferred radii well in excess of the largest known inflated Jovian planets.

  • 24. Zamora, O.
    et al.
    Garcia-Hernandez, D. A.
    Allende Prieto, C.
    Carrera, R.
    Koesterke, L.
    Edvardsson, Bengst
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Castelli, F.
    Plez, B.
    Bizyaev, D.
    Cunha, K.
    Garcia Perez, A. E.
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Holtzman, J. A.
    Lawler, J. E.
    Majewski, S. R.
    Manchado, A.
    Meszaros, Sz.
    Shane, N.
    Shetrone, M.
    Smith, V. V.
    Zasowski, G.
    New H-Band Stellar Spectral Libraries for the SdSS-III/Apogee Survey2015In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 149, no 6, article id 181Article in journal (Refereed)
    Abstract [en]

    The Sloan Digital Sky Survey-III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) has obtained high-resolution (R similar to 22,500), high signal-to-noise ratio (>100) spectra in the H-band (similar to 1.5-1.7 mu m) for about 146,000 stars in the Milky Way galaxy. We have computed spectral libraries with effective temperature (T-eff) ranging from 3500 to 8000 K for the automated chemical analysis of the survey data. The libraries, used to derive stellar parameters and abundances from the APOGEE spectra in the SDSS-III data release 12 (DR12), are based on ATLAS9 model atmospheres and the ASS epsilon T spectral synthesis code. We present a second set of libraries based on MARCS model atmospheres and the spectral synthesis code Turbospectrum. The ATLAS9/ASS epsilon T (T-eff = 3500-8000 K) and MARCS/Turbospectrum (T-eff = 3500-5500 K) grids cover a wide range of metallicity (-2.5 <= [M/H] <= + 0.5 dex), surface gravity (0 <= log g <= 5 dex), microturbulence (0.5 <= xi <= 8 km s(-1)), carbon (-1 <= [C/M] <= + 1 dex), nitrogen (-1 <= [N/M] <= + 1 dex), and alpha-element (-1 <= [alpha/M] <= + 1 dex) variations, having thus seven dimensions. We compare the ATLAS9/ASS.T and MARCS/Turbospectrum libraries and apply both of them to the analysis of the observed H-band spectra of the Sun and the K2 giant Arcturus, as well as to a selected sample of well-known giant stars observed at very high resolution. The new APOGEE libraries are publicly available and can be employed for chemical studies in the H-band using other high-resolution spectrographs.

1 - 24 of 24
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