Testing the asteroseismic estimates of stellar radii with surface brightness-colour relations and Gaia DR3 parallaxes. Red giants and red clump stars
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| Natura: | Preprint |
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2024
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| author | Valle, G. Dell'Omodarme, M. Moroni, P. G. Prada Degl'Innocenti, S. |
| author_facet | Valle, G. Dell'Omodarme, M. Moroni, P. G. Prada Degl'Innocenti, S. |
| contents | We compared stellar radii derived from asteroseismic scaling relations with those estimated using two independent surface brightness-colour relations (SBCRs) and Gaia DR3 parallaxes. We cross-matched asteroseismic and astrometric data for over 6,400 RGB and RC stars from the APO-K2 catalogue with the TESS Input Catalogue v8.2 to obtain precise V band magnitudes and E(B-V) colour excesses. We then adopted two different SBCRs from the literature to derive stellar radius estimates, denoted as $R^a$ and $R^b$, respectively. We analysed the ratio of these SBCR-derived radii to the asteroseismic radius estimates, $R$, provided in the APO-K2 catalogue. Both SBCRs exhibited good agreement with asteroseismic radius estimates. On average, $R^a$ was overestimated by 1.2% with respect to $R$, while $R^b$ was underestimated by 2.5%. For stars larger than 20 $R_{\odot}$, SBCR radii are systematically lower than asteroseismic ones. The agreement with asteroseismic radii shows a strong dependence on the parallax. The dispersion is halved for stars with a parallax greater than 2.5 mas. In this subsample, $R^b$ showed perfect agreement with $R$, while $R^a$ remained slightly overestimated by 3%. A trend with [Fe/H] of 4% to 6% per dex was found. For stars less massive than about 0.95 $M_{\odot}$, SBCR radii were significantly higher than asteroseismic ones, by about 6%. This overestimation correlated with the presence of extended helium cores in these stars' structures relative to their envelopes. Furthermore, radius ratios showed a dichotomous behaviour at higher masses, mainly due to the presence of several RC stars with SBCR radii significantly lower with respect to asteroseismology. This behaviour originates from a different response of asteroseismic scaling relations and SBCR to [$α$/Fe] abundance ratios for massive stars, both in RGB and RC phases, which is reported here for the first time. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_10050 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Testing the asteroseismic estimates of stellar radii with surface brightness-colour relations and Gaia DR3 parallaxes. Red giants and red clump stars Valle, G. Dell'Omodarme, M. Moroni, P. G. Prada Degl'Innocenti, S. Solar and Stellar Astrophysics Astrophysics of Galaxies We compared stellar radii derived from asteroseismic scaling relations with those estimated using two independent surface brightness-colour relations (SBCRs) and Gaia DR3 parallaxes. We cross-matched asteroseismic and astrometric data for over 6,400 RGB and RC stars from the APO-K2 catalogue with the TESS Input Catalogue v8.2 to obtain precise V band magnitudes and E(B-V) colour excesses. We then adopted two different SBCRs from the literature to derive stellar radius estimates, denoted as $R^a$ and $R^b$, respectively. We analysed the ratio of these SBCR-derived radii to the asteroseismic radius estimates, $R$, provided in the APO-K2 catalogue. Both SBCRs exhibited good agreement with asteroseismic radius estimates. On average, $R^a$ was overestimated by 1.2% with respect to $R$, while $R^b$ was underestimated by 2.5%. For stars larger than 20 $R_{\odot}$, SBCR radii are systematically lower than asteroseismic ones. The agreement with asteroseismic radii shows a strong dependence on the parallax. The dispersion is halved for stars with a parallax greater than 2.5 mas. In this subsample, $R^b$ showed perfect agreement with $R$, while $R^a$ remained slightly overestimated by 3%. A trend with [Fe/H] of 4% to 6% per dex was found. For stars less massive than about 0.95 $M_{\odot}$, SBCR radii were significantly higher than asteroseismic ones, by about 6%. This overestimation correlated with the presence of extended helium cores in these stars' structures relative to their envelopes. Furthermore, radius ratios showed a dichotomous behaviour at higher masses, mainly due to the presence of several RC stars with SBCR radii significantly lower with respect to asteroseismology. This behaviour originates from a different response of asteroseismic scaling relations and SBCR to [$α$/Fe] abundance ratios for massive stars, both in RGB and RC phases, which is reported here for the first time. |
| title | Testing the asteroseismic estimates of stellar radii with surface brightness-colour relations and Gaia DR3 parallaxes. Red giants and red clump stars |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2409.10050 |