A dataset provided by the European Space Agency

Name OT2_pkervell_2
Title The stellar wind of two Galactic Cepheids: a key to solve the evolutionary-pulsational mass discrepancy


DOI 10.5270/esa-y42j7dl
Author kervella, p.
Description Thanks to their Period-Luminosity law, Cepheids are among the most important class of stars. The recent discovery of circumstellar envelopes (CSEs) around Cepheids is an indication that many Cepheids, if not all, are surrounded by CSEs. The bright classical Cepheids RS Pup and delta Cephei are particularly interesting members of their famous class of variable stars, as they are known to be surrounded by large CSEs. Following our PACS and SPIRE imaging observations of the dusty circumstellar envelopes of these two Galactic Cepheids in OT1, we request spectroscopic observations of the same two targets to measure the physical conditions and composition of their stellar winds. Our scientific goal is to determine the physical conditions in the stellar winds, and pinpoint, in combination with other observations, the mass loss rate of these two benchmark stars. There is still today a significant discrepancy between the Cepheid masses estimated from evolutionary modeling, and pulsation modeling. The evolutionary modeling systematically predicts higher masses than the ''instantaneous", dynamical pulsating masses. This may indicate that massive stars experience significant mass loss episodes during their Cepheid phase. We aim at testing the hypothesis that pulsation driven stellar winds occur during the crossing of the instability strip, and are at the origin of this discrepancy.
Instrument PACS_PacsRangeSpec_point
Temporal Coverage 2012-12-04T04:30:29Z/2013-01-29T16:58:36Z
Version SPG v14.2.0
Mission Description Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 ┬Ám range, bridging the gap between earlier infrared space missions and groundbased facilities.
Creator Contact https://support.cosmos.esa.int/herschel/
Date Published 2013-07-29T15:43:37Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, 2013-07-29T15:43:37Z, OT2_pkervell_2, SPG v14.2.0. https://doi.org/10.5270/esa-y42j7dl