تقرير
HdC and EHe stars through the prism of Gaia DR3: 3D distribution and Gaia's chromatic PSF effects
| العنوان: | HdC and EHe stars through the prism of Gaia DR3: 3D distribution and Gaia's chromatic PSF effects |
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| المؤلفون: | Tisserand, P., Crawford, C. L., Soon, J., Clayton, G. C., Ruiter, A. J., Seitenzahl, I. R. |
| سنة النشر: | 2023 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies |
| الوصف: | Upon its release the Gaia DR3 catalogue has led to tremendous progress in multiple fields of astronomy by providing the complete astrometric solution for nearly 1.5 billion sources. We analysed the photometric and astrometric results for Hydrogen-deficient Carbon (HdC), Extreme Helium (EHe), and DYPer type stars to identify any potential biases and thus to select stars suitable for kinematic and spatial distribution studies. We investigated the impact of photometric declines in R Coronae Borealis (RCB) stars on Gaia astrometry using information from the Gaia IPD process cross-matched with light curves. We have reached the conclusion that the astrometric fits for numerous RCB stars are not valid due to the Gaia PSF chromaticity effect in both shape and centroid. The astrometric results of all stars with a significant time-dependent colour variation should be similarly affected. RCB stars might thus be promising sources to correct this effect in future Gaia releases. Furthermore, after validating the Gaia astrometric results for 92 stars, we observed that the majority of HdC and EHe stars are distributed across the three old stellar structures, the thick disk, the bulge and the halo. However, we have also uncovered evidence indicating that some of them exhibit orbits characteristic of the thin disk. This is also particularly true for all DYPer type stars studied. Finally, we have produced a list of star memberships for each Galactic substructure, and provided a list of heliocentric radial velocities and associated errors for targets not observed by Gaia DR3. We are beginning to observe a relationship between kinematics, stellar population, and metallicity in RCB and EHe stars. That relation can be explained, within the double degenerate scenario, by the large range in the delay time distribution expected from population synthesis simulations, particularly through the HybCO merger channel. Comment: 22 pages, 20 figures, accepted for publication in A&A v2: RV section from accompanying paper ArXiv2309.10139 moved into that one +New section added on the comparison between our classification of HdC and EHe stars within a Galactic substructure and the one published lately by Philip Monai et al. (2023), and between both results on dynamical orbital parameters as determined with Galpy simulations |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2309.10148 |
| رقم الأكسشن: | edsarx.2309.10148 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |