تقرير
The Extremely Metal Rich Knot of Stars at the Heart of the Galaxy
| العنوان: | The Extremely Metal Rich Knot of Stars at the Heart of the Galaxy |
|---|---|
| المؤلفون: | Rix, Hans-Walter, Chandra, Vedant, Zasowski, Gail, Pillepich, Annalisa, Khoperskov, Sergey, Feltzing, Sofia, Wyse, Rosemary F., Frankel, Neige, Horta, Danny, Kollmeier, Juna, Stassun, Keivan G., Ness, Melissa, Bird, Jonathan C., Nidever, David L., Fernandez, Jose G., Amarante, João A., Laporte, Chervin F., Lian, Jianhui |
| سنة النشر: | 2024 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | We show with Gaia XP spectroscopy that extremely metal-rich stars in the Milky Way (EMR; $[M/H]_{XP} > 0.5$) - but only those - are largely confined to a tight "knot" at the center of the Galaxy. This EMR knot is round in projection, has a fairly abrupt edge near $\sim 1.5$kpc, and is a dynamically hot system. This central knot also contains very metal-rich (VMR; $+0.2\le [M/H]_{XP} \le +0.4$) stars. However, in contrast to EMR stars, the bulk of VMR stars form an extended, highly flattened distribution in the inner Galaxy ($R_{\mathrm{GC}}\lesssim 5$ kpc). We draw on TNG50 simulations of Milky Way analogs for context and find that compact, metal-rich knots confined to $<1.5$kpc are a universal feature. In typical simulated analogs, the top 5-10% most metal-rich stars are confined to a central knot; however, in our Milky Way data this fraction is only 0.1%. Dust-penetrating wide-area near-infrared spectroscopy, such as SDSS-V, will be needed for a rigorous estimate of the fraction of stars in the Galactic EMR knot. Why in our Milky Way only EMR giants are confined to such a central knot remains to be explained. Remarkably, the central few kiloparsecs of the Milky Way harbor both the highest concentration of metal-poor stars (the `poor old heart') and almost all EMR stars. This highlights the stellar population diversity at the bottom of galactic potential wells. Comment: 11 pages, 7 figures, submitted to ApJ |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2406.01706 |
| رقم الأكسشن: | edsarx.2406.01706 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |