Green, PJ;
Montez, R;
Mazzoni, F;
Filippazzo, J;
Anderson, SF;
De Marco, O;
Drake, JJ;
... Roulston, BR; + view all
(2019)
A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer?
Astrophysical Journal
, 881
(1)
, Article 49. 10.3847/1538-4357/ab2bf4.
Preview |
Text
Green_2019_ApJ_881_49.pdf - Published Version Download (1MB) | Preview |
Abstract
Carbon stars (with C/O> 1) were long assumed to all be giants, because only AGB stars dredge up significant carbon into their atmospheres. The case is nearly iron-clad now that the formerly mysterious dwarf carbon (dC) stars are actually far more common than C giants, and have accreted carbon-rich material from a former AGB companion, yielding a white dwarf and a dC star that has gained both significant mass and angular momentum. Some such dC systems have undergone a planetary nebula phase, and some may evolve to become CH, CEMP, or Ba giants. Recent studies indicate that most dCs are likely from older, metal-poor kinematic populations. Given the well-known anti-correlation of age and activity, dCs would not be expected to show significant X-ray emission related to coronal activity. However, accretion spin-up might be expected to rejuvenate magnetic dynamos in these post mass-transfer binary systems. We describe our Chandra pilot study of six dCs selected from the SDSS for Halpha emission and/or a hot white dwarf companion, to test whether their X-ray emission strength and spectral properties are consistent with a rejuvenated dynamo. We detect all 6 dCs in the sample, which have X-ray luminosities ranging from logLx ~ 28.5 - 29.7, preliminary evidence that dCs may be active at a level consistent with stars that have short rotation periods of several days or less. More definitive results require a sample of typical dCs with deeper X-ray observations to better constrain their plasma temperatures.
| Type: | Article |
|---|---|
| Title: | A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer? |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/ab2bf4 |
| Publisher version: | https://doi.org/10.3847/1538-4357/ab2bf4 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | binaries: general; stars: carbon; stars: chemically peculiar; X-rays: stars |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10081514 |
Archive Staff Only
 |
View Item |
