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  • 251. Eriksson, S.
    et al.
    Elkington, S.R.
    Phan, T.D.
    Petrinec, S.M.
    Reme, H.
    Dunlop, M.W.
    Wiltberger, M.
    Balogh, A.
    Ergun, R.
    André, Mats
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Space and Plasma Physics.
    Global control of merging by the IMF: Cluster observations of dawnside flank magnetopause reconnection2004In: Geophys. Res., Vol. 109, p. A12203-Article in journal (Refereed)
  • 252.
    Festin, Leif
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    The faintest stars: A study of white, red and brown dwarfs1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The local space density of the faintest stars, including M dwarfs, white dwarfs and brown dwarfs has been studied by two different methods.

    By using dark nebulae as opaque outer screens, the luminosity functions of M dwarfs and white dwarfs were studied as volume-limited and dynamically unbiassed foreground samples. The surveyed volume corresponds to 464 pc3 in the solar neighbourhood and contains 21 M dwarfs and 7 white dwarfs. The derived M-dwarf luminosity function is consistent with previous findings, showing no substantial upturnbeyond Mv = 16. The white dwarf space density is consistent with a 20% fraction of the dynamical matter in the solar neighbourhood residing in white dwarfs. This is in line with the most recent independent results obtained with different methods, making the white dwarfs the best explanation to the Milky Way dark matter at present.

    The brown dwarfs were studied in the Pleiades open cluster. The distance and age of the Pleiades make the rapidly fading brown dwarfs still rather bright and easy to detect. 850 arcmin2 were covered in a deep RIJK survey. Nine new possible cluster members were discovered, four of which are below the brown dwarf limit. The faintest of these has an estimated mass of 0.040 M. and is thereby the lowest mass brown dwarf identified in the Pleiades cluster at present. The derived Pleiades substellar luminosity function is consistent with a mass function index between 0 and 1, making the brown dwarfs unlikely to contribute more than a few percent to the cluster mass, which is also consistent with recent dynamical results.

  • 253.
    Festou, MC
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Gunnarsson, M
    Rickman, H
    Winnberg, A
    Tancredi, G
    The activity of Comet 29P/Schwassmann-Wachmann 1 monitored through its CO J=2 -> 1 radio line2001In: ICARUS, ISSN 0019-1035, Vol. 150, no 1, p. 140-150Article in journal (Refereed)
    Abstract [en]

    The 230-GHz emission from CO was observed on 18 different days between 4 December 1996 and 1 January 1997 with the 15-m SEST antenna pointed toward Comet 29P/Schwassmann-Wachmann 1. The CO emission was measured at four different locations within the coma.

  • 254. Folsom, C. P.
    et al.
    Wade, G. A.
    Kochukhov, O.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Alecian, E.
    Catala, C.
    Bagnulo, S.
    Boehm, T.
    Bouret, J.-C.
    Donati, J.-F.
    Grunhut, J.
    Hanes, D. A.
    Landstreet, J. D.
    Magnetic fields and chemical peculiarities of the very young intermediate-mass binary system HD 721062008In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 391, no 2, p. 901-914Article in journal (Refereed)
    Abstract [en]

    The recently discovered magnetic Herbig Ae and Be stars may provide qualitatively new information about the formation and evolution of magnetic Ap and Bp stars. We have performed a detailed investigation of one particularly interesting binary system with a Herbig Ae secondary and a late B-type primary possessing a strong, globally ordered magnetic field. 20 high-resolution Stokes V spectra of the system were obtained with the ESPaDOnS instrument mounted on the Canada-France-Hawaii Telescope. In these observations we see clear evidence for a magnetic field in the primary, but no evidence for a magnetic field in the secondary. A detailed abundance analysis was performed for both stars, revealing strong chemical peculiarities in the primary and normal chemical abundances in the secondary. The primary is strongly overabundant in Si, Cr and other iron-peak elements, as well as Nd, and underabundant in He. The primary therefore appears to be a very young Bp star. In this context, line profile variations of the primary suggest non-uniform lateral distributions of surface abundances. Interpreting the 0.639 95 +/- 0.000 09 d variation period of the Stokes I and V profiles as the rotational period of the star, we have modelled the magnetic field geometry and the surface abundance distributions of Si, Ti, Cr and Fe using magnetic Doppler imaging. We derive a dipolar geometry of the surface magnetic field, with a polar strength B-d = 1230 G and an obliquity beta = 57 degrees. The distributions Ti, Cr and Fe are all qualitatively similar, with an elongated patch of enhanced abundance situated near the positive magnetic pole. The Si distribution is somewhat different, and its relationship to the magnetic field geometry less clear.

  • 255.
    Forme, F., Ogawa, Y. and Buchert, S.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Naturally enhanced ion acoustic fluctuations seen at different wavelengths.2001In: Journal of Geophysical Research, Vol. 106, p. 21503-21515Article in journal (Refereed)
    Abstract [en]

    The authors present European Incoherent Scatter (EISCAT) Svalbard Radar observations of enhanced incoherent scatter ion-acoustic spectra with transmitted frequencies slightly shifted relative to the radar central frequency. This study confirms the initial

  • 256. Fossati, L.
    et al.
    Bagnulo, S.
    Monier, R.
    Khan, S.A.
    Kochukhov, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Observational Astronomy.
    Landstreet, J.
    Wade, G.
    Weiss, W.
    Late stages of the evolution of A-type stars on the main sequence: Comparison between observed chemical abundances and diffusion models for 8 Am stars of the Praesepe cluster2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 476, no 2, p. 911-925Article in journal (Refereed)
    Abstract [en]

    Aims. We aim to provide observational constraints on diffusion models that predict peculiar chemical abundances in the atmospheres of Am stars. We also intend to check if chemical peculiarities and slow rotation can be explained by the presence of a weak magnetic field. Methods. We have obtained high resolution, high signal-to-noise ratio spectra of eight previously-classified Am stars, two normal A-type stars and one Blue Straggler, considered to be members of the Praesepe cluster. For all of these stars we have determined fundamental parameters and photospheric abundances for a large number of chemical elements, with a higher precision than was ever obtained before for this cluster. For seven of these stars we also obtained spectra in circular polarization and applied the LSD technique to constrain the longitudinal magnetic field. Results. No magnetic field was detected in any of the analysed stars. HD 73666, a Blue Straggler previously considered as an Ap (Si) star, turns out to have the abundances of a normal A-type star. Am classification is not confirmed for HD 72942. For HD 73709 we have also calculated synthetic Aa photometry that is in good agreement with the observations. There is a generally good agreement between abundance predictions of diffusion models and values that we have obtained for the remaining Am stars. However, the observed Na and S abundances deviate from the predictions by 0.6 dex and ≥0.25 dex respectively. Li appears to be overabundant in three stars of our sample.

  • 257. Fouchard, M.
    et al.
    Froeschlé, Ch.
    Valsecchi, G.B.
    Rickman, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Long term effects of the Galactic tide on cometary dynamics2006In: Celes.Mech.Dyn.Astron., Vol. 95, p. 299-326Article in journal (Refereed)
  • 258. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Breiter, Sławomir
    Ratajczak, Roman
    Valsecchi, Giovanni B.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: II. Modelling the Galactic Tide2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 273-296Chapter in book (Other academic)
  • 259. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Valsecchi, Giovanni B.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: I: Modelling the Stellar Perturbations2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 257-272Chapter in book (Other academic)
  • 260. Frebel, A.
    et al.
    Aoki, W.
    Christlieb, N.
    Ando, H.
    Asplund, M.
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Nucleosynthetic signatures of the first stars2005In: Nature, Vol. 434, p. 871-873Article in journal (Refereed)
  • 261. Frebel, A
    et al.
    Aoki, W
    Christlieb, N
    Ando, H
    Asplund, M
    Barklem, Paul
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Beers, T.C.
    Eriksson, Kjell
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy. Theoretical Astrophysics.
    Fechner, C.
    Fujimoto, M.Y.
    The new record holder for the most iron-poor star: HE 1327 2326: A dwarf or subgiant with Fe/H = -5.42005In: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution: IAU Symposium 228, 2005, p. p. 207-212Conference paper (Other scientific)
  • 262. Frebel, Anna
    et al.
    Christlieb, Norbert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Norris, John E.
    Thom, Christopher
    Beers, Timothy C.
    Rhee, Jaehyon
    Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium2007In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 660, no 2, p. L117-L120Article in journal (Refereed)
    Abstract [en]

    We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523 - 0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523 - 0901 to be strongly overabundant in r- process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z > 56) measured in HE 1523 - 0901 match the scaled solar r- process pattern extremely well. We detect the strongest optical U line at 3859.57 angstrom. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/ Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523 - 0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.

  • 263. Frebel, Anna
    et al.
    Collet, Remo
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Christlieb, Norbert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Aoki, Wako
    HE 1327-2326, an unevolved star with [Fe/H] < , -5.0. II. New 3D-1D corrected abundances from a very large telescope UVES spectrum2008In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 684, no 1, p. 588-602Article in journal (Refereed)
    Abstract [en]

    We present a new abundance analysis of HE 1327-2326, which is currently the most iron-poor star, based on observational data obtained with the VLT Ultraviolet and Visual Echelle Spectrograph (UVES). We correct the one-dimensional (1D) LTE abundances for three-dimensional (3D) effects to provide an abundance pattern that supersedes previous works and should be used to observationally test current models of the chemical yields of the first-generation supernovae (SNe). Apart from confirming the 1D LTE abundances found in previous studies before accounting for 3D effects, we make use of a novel technique to apply the 3D 1D corrections for CNO which are a function of excitation potential and line strength for the molecular lines that comprise the observable CH, NH, and OH features. We find that the fit to the NH band at 33608 is greatly improved due to the application of the 3D-1D corrections. This may indicate that 3D effects are actually observable in this star. We also report the first detection of several weak Ni lines. The cosmologically important element Li is still not detected, the new Li upper limit is extremely low, A(Li) < , 0: 62, and in stark contrast with results not only from the Wilkinson Microwave Anisotropy Probe (WMAP) but also from other metal-poor stars. We also discuss how the new corrected abundance pattern of HE 1327-2326 is being reproduced by individual and integrated yields of SNe.

  • 264. Frebel, Anna
    et al.
    Norris, John E.
    Aoki, Wako
    Honda, Satoshi
    Bessell, Michael S.
    Takada-Hidai, Masahide
    Beers, Timothy C.
    Christlieb, Norbert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Chemical abundance analysis of the extremely metal-poor star HE 1300+01572007In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 658, no 1, p. 534-552Article in journal (Refereed)
    Abstract [en]

    We present a detailed chemical abundance analysis of HE 1300+0157, a subgiant with Fe/H = -3.9. Froma high-resolution, high-S/N Subaru HDS spectrum we find the star to be enriched in C ([C/Fe](1D) similar to +1.4) and O ([O/Fe](1D) similar to +1.8). With the exception of these species, HE 1300+0157 exhibits an elemental abundance pattern similar to that found in many other very and extremely metal-poor stars. The Li abundance is lower than the Spite plateau value, in agreement with expectation for its evolutionary status. Of particular interest, no neutron-capture elements are detected in HE 1300+0157. This type of abundance pattern has been found by recent studies in several other metal-poor giants. We suggest that HE 1300+0157 is an unevolved example of this group of stars, which exhibit high C abundances together with low (or absent) abundances of neutron-capture elements (CEMP-no). Several potential enrichment scenarios are presented. The nondetection of neutron-capture elements including Sr, Ba, and Pb suggests that the carbon excess observed in HE 1300+0157 is not due to mass transfer across a binary system. Such a scenario is applied to carbon-rich objects with excesses of s-process elements. The normal observed Li abundance supports this interpretation. Most likely, the high levels of C and O were produced prior to the birth of this star. It remains unclear whether a single faint SN is responsible for its overall chemical pattern, or whether one requires a superposition of yields from a massive Population III object and a hypernova. These scenarios provide important information on the C production in the early universe and on the formation of C-rich stars in the early Galaxy.

  • 265.
    Freytag, B.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Höfner, S.
    Three-dimensional model of the atmosphere of an AGB star2003In: Astronomische Nachrichten, 2003, Vol. 324, no Supl.Issue 3, p. 173-Conference paper (Other scientific)
  • 266.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    3D Simulation of Convection and Spectral Line Formation in A-type Stars2005In: Astro Ph., Vol. 09Article in journal (Refereed)
  • 267.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    3D Simulation of the Solar Granulation: A Comparison of two Different Hydrodynamic Codes2003In: ans, Vol. 07Article in journal (Refereed)
  • 268.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Acoustic Energy Generated by Convection: 3-D Numerical Simulations för the Sun2001In: AGMArticle in journal (Other (popular scientific, debate etc.))
  • 269.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Betelgeuse-Improved Numerical Simulations of an Entire Supergiant2003In: ANS, Vol. 07Article in journal (Refereed)
  • 270.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Betelgeuse-Improved Numerical Simulations of an Entire Supergiant2002In: AGAbArticle in journal (Refereed)
  • 271.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Betelgeuse-Numerical Simulations of an Entire Supergiant2001In: AGMArticle in journal (Refereed)
  • 272.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Hot Spots in Numerical Simulations of Betelgeuse2003In: csss, Vol. 10Article in journal (Refereed)
  • 273.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Hydrodynamical models of mixing beyond a convection zone2002In: HiAArticle in journal (Refereed)
  • 274.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Modelling the Chromospheric Background Pattern of the Non-magnetic Sun2003In: ANS, Vol. 07Article in journal (Refereed)
  • 275.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Numerical simulations of convection in A-stars2004In: IAUS, Vol. 12Article in journal (Refereed)
  • 276.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Stellar Surface Convection from White Dwarfs to Red Supergiants2001In: ASPCArticle in journal (Refereed)
  • 277.
    Freytag, Bernd
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    The shock-patterned solar chromosphere in teh light of ALMA2005In: Astro Ph., Vol. 09Article in journal (Refereed)
  • 278.
    Freytag, Bernd
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Finnsson, Sigurdur
    Typical Scales of Structures in Numerical Models of Betelgeuse2002In: Modelling of Stellar Atmospheres, IAU Symposium 210, San Francisco: The Astronomical Society of the Pacific , 2002Conference paper (Other scientific)
    Abstract [en]

    3D radiation hydrodynamics simulations of the envelope and atmosphere of a red supergiant show giant convection cells with sometimes deep-reaching downdrafts. Smaller short-lived cells can appear in the very outer layers. The surface intensity pattern is

  • 279.
    Freytag, Bernd
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Mizuno-Wiedner, Michelle
    Modelling the Entire Atmosphere of Betelgeuse with 3D Simulations2002In: Modelling of Stellar Atmospheres, IAU Symposium 210, San Francisco: The Astronomical Society of the Pacific , 2002Conference paper (Other scientific)
    Abstract [en]

    The large amount of observational data on Betelgeuse points to a highly dynamical atmosphere with phenomena that have not yet been described in detail by theory. Efforts to improve theoretical understanding are being made with the help of the COBOLD compu

  • 280.
    Freytag, Bernd
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Steffen, Matthias
    Dorch, Bertil
    Spots on the surface of Betelgeuse -- Results from new 3D stellar convection models2002In: Astronomische Nachrichten, no 323, p. 213-219Article in journal (Refereed)
    Abstract [en]

    The observed irregular brightness fluctuations of the well-known red supergiant Betelgeuse (alpha Ori, M2 Iab) have been attributed by M. Schwarzschild (1975) to the changing granulation pattern formed by only a few giant convection cells covering the sur

  • 281.
    Garcia-Perez, Ana Elia
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, Martin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Theoretical Astrophysics.
    Kiselman, D.
    Departure from LTE in Be line formation2001Conference paper (Other (popular scientific, debate etc.))
  • 282.
    García Pérez, Ana Elia
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    On the Abundances of Li, Be and O in Metal-Poor Stars in the Galaxy2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stellar atmospheres constitute excellent environments to study the chemical evolution of our Galaxy. The chemical composition of these atmospheres reflects the composition of the gas from where these stars were born. As the Galaxy evolves, the composition of the gas changes from being primordial (Big-Bang nucleosynthesis) to being enriched in heavy elements (stellar and interstellar nucleosynthesis). The abundances of fragile chemical elements can be affected by stellar mixing processes. Precise lithium, beryllium and oxygen abundance determinations in old stars are presented in this thesis. These determinations are based on the analysis of the observed spectra of a sample of thirteen metal-poor subgiant stars. According to stellar mixing theories, these stars are in a stellar evolutionary stage in which mixing by convection is expected. Abundances of fragile elements like lithium and beryllium are thus expected to be affected by such mixing processes. As a consequence of this, the abundances of these elements are discussed in a dilution context. Lithium and beryllium abundances are compared with the abundances of stars with similar characteristics but in a less evolved stellar phase so that mixing processes have not acted yet. As expected, our abundances seem to be depleted following reasonably well the standard predictions. Stellar abundances of oxygen should give an estimate of the oxygen contribution of core-collapse supernovae to the interstellar medium. However, there is poor agreement among the abundances determined from different atomic or molecular indicators in general. Abundances coming from three different indicators are compared in this thesis. The abundances determined from the O I infrared triplet lines at 777.1-5 nm give the poorest agreement among the three indicators. The abundances based on OH ultraviolet lines around 310 nm are lower for the subgiants in comparison with previous studies of main-sequence stars, becoming even lower than values based on the O I forbidden line at 630.03 nm. Still the most reliable indicator appears to be the O I forbidden line which suggests a plateau-like or only slowly increasing [O/Fe] towards lower [Fe/H]. In addition, the line formation of the Be II ultraviolet resonance lines at 313.0-1 nm, commonly used for abundance determinations purposes, is investigated under non-local thermodynamic equilibrium. We find that the common assumption of local thermodynamic equilibrium typically gives systematic errors of about 0.1 dex.

    List of papers
    1. Oxygen abundances in metal-poor subgiants as determined from [OI], OI and OH lines
    Open this publication in new window or tab >>Oxygen abundances in metal-poor subgiants as determined from [OI], OI and OH lines
    Show others...
    2006 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 451, no 2, p. 621-642Article in journal (Refereed) Published
    Abstract [en]

    The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the Ultraviolet and Visual Echelle Spectrograph at VLT, with a signal-to-noise of the order of 100 in the near ultraviolet and 500 in the optical and near infrared wavelength range. Three different oxygen abundance indicators, OH ultraviolet lines around 310.0 nm, the [O I] line at 630.03 nm and the O I lines at 777.1-5 nm were observed in the spectra of 13 metal-poor subgiants with . Oxygen abundances were obtained from the analysis of these indicators which was carried out assuming local thermodynamic equilibrium and plane-parallel model atmospheres. Abundances derived from O I were corrected for departures from local thermodynamic equilibrium. Stellar parameters were computed using -vs.-color calibrations based on the infrared flux method and Balmer line profiles, Hipparcos parallaxes and lines. [O/Fe] values derived from the forbidden line at 630.03 nm are consistent with an oxygen/iron ratio that varies linearly with [Fe/H] as . Values based on the O I triplet are on average (s.d.) higher than the values based on the forbidden line while the agreement between OH ultraviolet lines and the forbidden line is much better with a mean difference of the order of (s.d.). In general, our results follow the same trend as previously published results with the exception of the ones based on OH ultraviolet lines. In that case our results lie below the values which gave rise to the oxygen abundance debate for metal-poor stars.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-92684 (URN)10.1051/0004-6361:20053181 (DOI)
    Available from: 2005-02-24 Created: 2005-02-24 Last updated: 2017-12-14Bibliographically approved
    2. Li and Be depletion in metal-poor subgiants
    Open this publication in new window or tab >>Li and Be depletion in metal-poor subgiants
    2006 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 447, no 1, p. 299-310Article in journal (Refereed) Published
    Abstract [en]

    A sample of metal-poor subgiants has been observed with the UVES spectrograph at the Very Large Telescope and abundances of Li and Be have been determined. Typical signal-to-noise per spectral bin values for the co-added spectra are of the order of 500 for the line (670.78 nm) and 100 for the doublet lines (313.04 nm). The spectral analysis of the observations was carried out using the Uppsala suite of codes and MARCS (1D-LTE) model atmospheres with stellar parameters from photometry, parallaxes, isochrones and Fe II lines. Abundance estimates of the light elements were corrected for departures from local thermodynamic equilibrium in the line formation. Effective temperatures and Li abundances seem to be correlated and Be abundances correlate with [O/H]. Standard models predict Li and Be abundances approximately one order of magnitude lower than main-sequence values which is in general agreement with the observations. On average, our observed depletions seem to be 0.1 dex smaller and between 0.2 and 0.4 dex larger (depending on which reference is taken) than those predicted for Li and Be, respectively. This is not surprising since the initial Li abundance, as derived from main-sequence stars on the Spite plateau, may be systematically in error by 0.1 dex or more, and uncertainties in the spectrum normalisation and continuum drawing may affect our Be abundances systematically.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-92685 (URN)10.1051/0004-6361:20053182 (DOI)
    Available from: 2005-02-24 Created: 2005-02-24 Last updated: 2017-12-14Bibliographically approved
    3. Departures from LTE in the formation of the BeII UV resonance lines in late type stars
    Open this publication in new window or tab >>Departures from LTE in the formation of the BeII UV resonance lines in late type stars
    In: Astronomy & AstrophysicsArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-92686 (URN)
    Available from: 2005-02-24 Created: 2005-02-24Bibliographically approved
    Download full text (pdf)
    FULLTEXT01
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    COVER01
  • 283.
    García Pérez, Ana Elia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Asplund, Martin
    Primas, Francesca
    Nissen, Poul Erik
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Oxygen abundances in metal-poor subgiants as determined from [OI], OI and OH lines2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 451, no 2, p. 621-642Article in journal (Refereed)
    Abstract [en]

    The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the Ultraviolet and Visual Echelle Spectrograph at VLT, with a signal-to-noise of the order of 100 in the near ultraviolet and 500 in the optical and near infrared wavelength range. Three different oxygen abundance indicators, OH ultraviolet lines around 310.0 nm, the [O I] line at 630.03 nm and the O I lines at 777.1-5 nm were observed in the spectra of 13 metal-poor subgiants with . Oxygen abundances were obtained from the analysis of these indicators which was carried out assuming local thermodynamic equilibrium and plane-parallel model atmospheres. Abundances derived from O I were corrected for departures from local thermodynamic equilibrium. Stellar parameters were computed using -vs.-color calibrations based on the infrared flux method and Balmer line profiles, Hipparcos parallaxes and lines. [O/Fe] values derived from the forbidden line at 630.03 nm are consistent with an oxygen/iron ratio that varies linearly with [Fe/H] as . Values based on the O I triplet are on average (s.d.) higher than the values based on the forbidden line while the agreement between OH ultraviolet lines and the forbidden line is much better with a mean difference of the order of (s.d.). In general, our results follow the same trend as previously published results with the exception of the ones based on OH ultraviolet lines. In that case our results lie below the values which gave rise to the oxygen abundance debate for metal-poor stars.

  • 284.
    García Pérez, Ana Elia
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Kiselman, Dan
    Departures from LTE in the formation of the BeII UV resonance lines in late type starsIn: Astronomy & AstrophysicsArticle in journal (Refereed)
  • 285.
    García Pérez, Ana Elia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Primas, Francesca
    Li and Be depletion in metal-poor subgiants2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 447, no 1, p. 299-310Article in journal (Refereed)
    Abstract [en]

    A sample of metal-poor subgiants has been observed with the UVES spectrograph at the Very Large Telescope and abundances of Li and Be have been determined. Typical signal-to-noise per spectral bin values for the co-added spectra are of the order of 500 for the line (670.78 nm) and 100 for the doublet lines (313.04 nm). The spectral analysis of the observations was carried out using the Uppsala suite of codes and MARCS (1D-LTE) model atmospheres with stellar parameters from photometry, parallaxes, isochrones and Fe II lines. Abundance estimates of the light elements were corrected for departures from local thermodynamic equilibrium in the line formation. Effective temperatures and Li abundances seem to be correlated and Be abundances correlate with [O/H]. Standard models predict Li and Be abundances approximately one order of magnitude lower than main-sequence values which is in general agreement with the observations. On average, our observed depletions seem to be 0.1 dex smaller and between 0.2 and 0.4 dex larger (depending on which reference is taken) than those predicted for Li and Be, respectively. This is not surprising since the initial Li abundance, as derived from main-sequence stars on the Spite plateau, may be systematically in error by 0.1 dex or more, and uncertainties in the spectrum normalisation and continuum drawing may affect our Be abundances systematically.

  • 286. Gautschy-Loidl, Rita
    et al.
    Höfner, Susanne
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Jørgensen, Uffe G.
    Hron, Josef
    Dynamic model atmospheres of AGB stars: IV. A comparison of synthetic carbon star spectra with observations2004In: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 422, p. 289-306Article in journal (Refereed)
    Abstract [en]

    We have calculated synthetic opacity sampling spectra for carbon-rich Asymptotic Giant Branch (AGB) stars based on dynamic model atmospheres which couple time-dependent dynamics and frequency-dependent radiative transfer, as presented in the third paper of this series. We include the molecules CO, CH, CN, C2, CS, HCN, C2H2 and C3 in our calculations, both when computing the atmospheric structures, and the synthetic spectra. A comparison of the synthetic spectra with various observed colours and spectra in the wavelength range between 0.5 and 25 μm,of TX Psc, WZ Cas, V460 Cyg, T Lyr and S Cep is presented. We obtain good agreement between observations gathered at different phases and synthetic spectra of one single hydrodynamical model for each star in the wavelength region between 0.5 and 5 μm. At longer wavelengths our models showing mass loss offer a first self-consistent qualitative explanation of why a strong feature around 14 μm, which is predicted by all hydrostatic models as well as dynamical models showing no mass loss, is missing in observed AGB carbon star spectra.

  • 287. Gehren, Thomas
    et al.
    Shi, Jianrong
    Zhang, Huawei
    Zhao, Gang
    Korn, Andreas J.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Observational Astronomy.
    Na, Mg and Al abundances as a population discriminant for nearby metal-poor stars2006In: Astronomy & Astrophysics, no 451, p. 1065-1079Article in journal (Other (popular scientific, debate etc.))
    Abstract [en]

    Aims. Parameters for 55 nearby metal-poor stars are determined using high-resolution spectroscopy. Together with similar data taken

    from a recent analysis, they are used to show trends of their Galactic evolution with stellar [Fe/H] or [Mg/H] abundances. The

    separation of abundance ratios between disk and halo stars is used as a basic criterion for population membership.

    Methods. After careful selection of a clean subsample free of suspected or known binaries and peculiar stars, abundances of Mg, Na and Al are based on NLTE kinetic equilibrium calculations applied to spectrum synthesis methods.

    Results. The relation between [Na/Mg] and [Fe/H] is a continuous enrichment through all three Galactic populations spanning a range

    of values between a metal-poor plateau at [Na/Mg] = −0.7 and solar values. [Al/Mg] displays a step-like difference between stars

    of the Galactic halo with [Al/Mg] ∼ −0.45 and the two disk populations with [Al/Mg] ∼ +0.10. [Al/Mg] ratios, together with the

    [Mg/Fe] ratios, asymmetric drift velocities V, and stellar evolutionary ages, make possible the individual discrimination between stars of the thick disk and the halo. At present, this evidence is limited by the small number of stars, and by the theoretical and empirical uncertainties of stellar age determinations, but it achieves a high significance.

    Conclusions. While the stellar sample is not complete with respect to space volume, the resulting abundances indicate the necessity

    to revise current models of chemical evolution to allow for an adequate production of Al in early stellar generations.

  • 288.
    Gelbmann, M
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Ryabchikova, T
    Weiss, WW
    Piskunov, N
    Kupka, F
    Mathys, G
    Abundance analysis of roAp stars - V. HD 1664732000In: ASTRONOMY AND ASTROPHYSICS, ISSN 0004-6361, Vol. 356, no 1, p. 200-208Article in journal (Refereed)
    Abstract [en]

    This fifth paper in a sequence on abundance analyses of roAp stars features several improvements and complements over the previous investigations: i. The new VALD-2 atomic data base was used which significantly improves the analysis of C, N, O, and rare e

  • 289.
    González Delgado, D.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Olofsson, H.
    Schwarz, H. E.
    Eriksson, K.
    Gustafsson, B.
    Gledhill, T.
    Imaging polarimetry of stellar light scattered in detached shells around the carbon stars R Scl and U Ant2003In: Astronomy & Astrophysics, Vol. 399, p. 1021-1035Article in journal (Refereed)
  • 290. Goswami, Aruna
    et al.
    Aoki, Wako
    Beers, Timothy C.
    Christlieb, Norbert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Norris, John E.
    Ryan, Sean G.
    Tsangarides, Stelios
    A high-resolution spectral analysis of three carbon-enhanced metal-poor stars2006In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 372, no 1, p. 343-356Article in journal (Refereed)
    Abstract [en]

    We present results of an analysis of high-resolution spectra (R similar to 50 000), obtained with the Subaru Telescope High Dispersion Spectrograph, of two carbon-enhanced metal-poor (CEMP) stars selected from the Hamburg/European Southern Observatory prism survey, HE 1305+0007 and HE 1152-0355, and of the classical CH star HD 5223. All these stars have relatively low effective temperatures (4000-4750 K) and high carbon abundances, which result in the presence of very strong molecular carbon bands in their spectra. The stellar atmospheric parameters for these stars indicate that they all have surface gravities consistent with a present location on the red giant branch, and metallicities of [Fe/H] = -2.0 (HE 1305+0007, HD 5223) and [Fe/H] = -1.3 (HE 1152-0355). In addition to their large enhancements of carbon ([C/Fe] = +1.8, +1.6, and +0.6, respectively), all three stars exhibit strong enhancements of the s-process elements relative to iron. HE 1305+0007 exhibits a large enhancement of the third-peak s-process element, lead, with [Pb/Fe] = +2.37, as well as a high abundance of the r-process element europium, [Eu/Fe] = +1.97. The second-peak s-process elements, Ba, La, Ce, Nd and Sm, are found to be more enhanced than the first-peak s-process elements Zr, Sr and Y. Thus, HE 1305+0007 joins the growing class of the so-called 'Lead stars', and also the class of objects that exhibit the presence of both r- and s-process elements, the CEMP-r/s stars. The large enhancements of neutron-capture (n-capture) elements exhibited by HE 1152-0355 and HD 5223 are more consistent with the abundance patterns generally noticed in CH stars, essentially arising from pure s-process nucleosynthesis. The elemental abundance distributions observed in these stars are discussed in light of existing theories of CH star formation, as well as the suggested formation scenarios of the CEMP-r/s group.

  • 291. Graves, Jonathan
    et al.
    Wahlberg, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Safety factor corrections to the magnetohydrodynamic internal kink mode in a tokamak2007In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 14, no 8, p. 082504-Article in journal (Refereed)
    Abstract [en]

    It has long been acknowledged that the well known and frequently used stability criterion beta_p < 0.3 for the toroidal ideal magnetohydrodynamic internal kink mode in a tokamak is inaccurate for an empirically relevant safety factor. The present paper outlines the severity of the usual approximation, and presents improved analytical approximations of the general solution in M. N. Bussac, R. Pellat, D. Edery, and J. L. Soulé, Phys. Rev. Lett. 35, 1638 (1975), thus providing new insights into the nature of the instability, together with simple formulas that can be incorporated into transport codes with sawtooth cycle algorithms.

  • 292.
    Gunnarsson, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Bockelee-Morvan, D.
    Biver, N.
    Crovisier, J.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 12008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 484, no 2, p. 537-546Article in journal (Refereed)
    Abstract [en]

    Context. CO is assumed to be the main driver behind the activity of comet 29P/Schwassmann-Wachmann 1, which resides in a near-circular orbit at 6 AU from the Sun. Several properties of the outgassing of CO can be deduced from its millimetre-wave emission. Earlier studies have indicated CO production from the nucleus as well as an extended source. Aims. We have sought to further investigate the nature of the CO production in comet 29P/Schwassmann-Wachmann 1, through the use of newly available instrumentation. Methods. We used the HERA receiver array on the 30-m IRAM telescope to map the 230 GHz CO(J = 2-1) line in the comet with an unprecedented sensitivity and spatial coverage, and a high spectral resolution (20 kHz, i.e., 25 m s(-1)). A 36-point map, 60 by 60 '', was obtained in June 2003, and a 25-point map, 96 by 96 '', in January 2004. Results. The CO emission line has a characteristic asymmetric profile. Our analysis is based on a coma model, where the outgassing pattern is derived from the shape of this line at the central position of the map. When comparing to the observations, both maps show a line intensity at offset positions that is 2-3 times stronger than the model prediction. Different explanations for this are evaluated, and it is found that for the global coma character, an extremely low gas temperature in the inner coma reproduces the observed radial profile. A cold inner coma depletes the population of the CO J = 2 rotational level in the region closest to the nucleus, making spectra observed at offset positions relatively stronger. From the global appearance of the maps, the coma was found to be largely axisymmetric, and the presence of a strong extended source of CO, as indicated from earlier observations using the SEST telescope, was not seen. When examining the maps in more detail, a possible exception to this was seen in an area similar to 30 '' south of the comet, where an excess in emission is present in both maps. Model fits to the spectra based on the cold inner coma that we find, with an intital kinetic temperature T(kin) = 4 K, give a measure of Q(CO), the CO production rate. Q(CO) was found to be (3.9 +/- 0.2) x 10(28) mol s(-1) in June 2003, and (3.7 +/- 0.2) x 10(28) mol s(-1) in January 2004. These values are a factor similar to 1.5 higher than that derived using only the information available from non-mapped data, and this adjustment applies also to previously published production rates.

  • 293.
    Gunnarsson, M.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory.
    Bockelée-Morvan, D.
    Winnberg, A.
    Rickman, H.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Faculty of Science and Technology, Astronomical observatory.
    Crovisier, J.
    Biver, N.
    Colom, P.
    Davies, J.K.
    Despois, D.
    Henry, F.
    Johansson, L.E.B.
    Moreno, R.
    Paubert, G.
    Rantakyrö, F.T.
    Rauer, H.
    Production and Kinematics of CO in Comet 1995 O1 (Hale-Bopp) at Large Post-Perihelion Distances2003In: Astronomy & Astrophysics, Vol. 402, p. 383-393Article in journal (Refereed)
  • 294.
    Gunnarsson, M., Rickman, H., Festou, M. C., Winnberg, A. and Tancredi, G.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    An Extended CO Source around Comet 29P/Schwassmann-Wachmann 12002In: Icarus, Vol. 157, p. 309-322Article in journal (Refereed)
  • 295.
    Gunnarsson, Marcus
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Gas Production in Distant Comets2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Molecular spectroscopy at radio wavelengths is a tool well suited for studying the composition and outgassing kinematics of cometary comae. This is particularly true for distant comets, i.e. comets at heliocentric distances greater than a few AU, where the excitation of molecules is inefficient other than for rotational energy levels. At these distances, water sublimation is inefficient, and cometary activity is dominated by outgassing of carbon monoxide.

    An observing campaign is presented, where the millimeter-wave emission from CO in comet 29P/Schwassmann-Wachmann 1 has been studied in detail using the Swedish-ESO Submillimetre Telescope (SEST). Coma models have been used to analyse the spectra. The production of CO is found to have two separate sources, one releasing CO gas on the nuclear dayside, and one extended source, where CO is produced from coma material, proposed to be icy dust grains.

    Radio observations of many molecules in comet C/1995 O1 (Hale-Bopp) have been carried out in a long-term international effort using several radio telescopes. An overview of the results is presented, describing the evolution of the gas production as the comet passed through the inner Solar system. Spectra recorded using the SEST, primarily of CO, for heliocentric distances from 3 to 11 AU are analysed in detail, also using coma models.

    The concept of icy grains constituting the extended source discovered in comet 29P/Schwassmann-Wachmann 1 is examined by theoretical modelling of micrometre-sized ice/dust particles at 6 AU from the Sun. It is shown that that such grains can release their content of volatiles on timescales similar to that found for the extended source.

    Download full text (pdf)
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  • 296. Gurnett, D.A.
    et al.
    Kurth, W.S.
    Kirchner, G.B.
    Hospodarsky, G.B.
    Averkamp, T.F.
    Zarka, P.
    Lecacheux, A.
    Manning, R.
    Roux, C.P.
    Cornilleau-Wehrlin, N.
    Galopeau, P.
    Meyer, A.
    Boström, Rolf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Space and Plasma Physics.
    Gustafsson, Georg
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics. Department of Physics and Astronomy, Space and Plasma Physics.
    Wahlund, Jan-Erik
    The Cassini Radio and Plasma Wave Investigation2004In: Space Sci. Rev., Vol. 114, p. 395-Article in journal (Refereed)
  • 297.
    Gustafsson, B.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    The current status of modelling of stellar atmospheres2003In: Modelling of Stellar Atmosheres, Proc. of 210th IAU Symposium, Vol. 210, p. 3-18Article, book review (Other scientific)
  • 298.
    Gustafsson, B.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Edvardsson, B.
    Eriksson, K.
    Mizuno-Wiedner, M.
    Jørgensen, U. G.
    Plez, B.
    A Grid of Model Atmospheres for Cool Stars2003In: "Stellar Atmosphere Modeling", ASP Conference Proceedings, Astronomical Society of the Pacific , 2003, Vol. 288, p. p. 331-334Conference paper (Other scientific)
  • 299.
    Gustafsson, B.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Höfner, S.
    Atmospheres of AGB stars2004In: Asymptotic Giant Branch Stars, Springer-Verlag, New York , 2004, p. 149-245Chapter in book (Refereed)
  • 300.
    Gustafsson, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Bildning och fysik: Vad betyder vävens mönster?2006Book (Other (popular scientific, debate etc.))
3456789 251 - 300 of 1015
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