Absorbing gas around the WASP-12 planetary system
2013 (English)In: ASTROPHYSICAL JOURNAL LETTERS, ISSN 2041-8205, Vol. 766, no 2, L20- p.Article in journal (Refereed) Published
Near-UV observations of the planet host star WASP-12 uncovered the apparent absence of the normally conspicuous core emission of the Mg II h and k resonance lines. This anomaly could be due either to (1) a lack of stellar activity, which would be unprecedented for a solar-like star of the imputed age of WASP-12 or (2) extrinsic absorption, from the intervening interstellar medium (ISM) or from material within the WASP-12 system itself, presumably ablated from the extreme hot Jupiter WASP-12 b. HIRES archival spectra of the Ca II H and K lines of WASP-12 show broad depressions in the line cores, deeper than those of other inactive and similarly distant stars and similar to WASP-12's Mg II h and k line profiles. We took high-resolution ESPaDOnS and FIES spectra of three early-type stars within 20' of WASP-12 and at similar distances, which show the ISM column is insufficient to produce the broad Ca II depression observed in WASP-12. The EBHIS H I column density map supports and strengthens this conclusion. Extrinsic absorption by material local to the WASP-12 system is therefore the most likely cause of the line core anomalies. Gas escaping from the heavily irradiated planet could form a stable and thick circumstellar disk/cloud. The anomalously low stellar activity index (logR'(HK)) of WASP-12 is evidently a direct consequence of the extra core absorption, so similar HK index deficiencies might signal the presence of translucent circumstellar gas around other stars hosting evaporating planets.
Place, publisher, year, edition, pages
2013. Vol. 766, no 2, L20- p.
ISM: clouds, planets and satellites: individual (WASP-12), planet-star interactions, stars: individual (WASP-12)
IdentifiersURN: urn:nbn:se:uu:diva-198600DOI: 10.1088/2041-8205/766/2/L20ISI: 000316322200006OAI: oai:DiVA.org:uu-198600DiVA: diva2:617464