The Metal-poor Metallicity Distribution of the Ancient Milky Way
Chiti,Anirudh1; Mardini,Mohammad K.2,3; Frebel,Anna1; Daniel,Tatsuya4
Source PublicationThe Astrophysical Journal Letters
AbstractAbstract We present a low-metallicity map of the Milky Way consisting of ~110,000 metal-poor giants with ?3.5 < [Fe/H] < ?0.75, based on public photometry from the second data release of the SkyMapper survey. These stars extend out to ~7 kpc from the solar neighborhood and cover the main Galactic stellar populations, including the thick disk and the inner halo. Notably, this map can reliably differentiate metallicities down to [Fe/H] ~ ?3.0, and thus provides an unprecedented view into the ancient, metal-poor Milky Way. Among the more metal-rich stars in our sample ([Fe/H] > ?2.0), we recover a clear spatial dependence of decreasing mean metallicity as a function of scale height that maps onto the thick disk component of the Milky Way. When only considering the very metal-poor stars in our sample ([Fe/H] < ?2), we recover no such spatial dependence in their mean metallicity out to a scale height of ∣Z∣ ~ 7 kpc. We find that the metallicity distribution function (MDF) of the most metal-poor stars in our sample (?3.0 < [Fe/H] < ?2.3) is well fit with an exponential profile with a slope of and [Fe/H] = 1.52 ± 0.05, and slightly shifts to after accounting for target selection effects. For [Fe/H] < ?2.3, the MDF is largely insensitive to scale height ∣Z∣ out to ~5 kpc, showing that very and extremely metal-poor stars are in every galactic component.
KeywordPopulation II stars Milky Way Galaxy
WOS IDIOP:2041-8205-911-2-abd629
PublisherThe American Astronomical Society
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Document Type期刊论文
Corresponding AuthorChiti,Anirudh
Affiliation1.Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;
2.Key Lab of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
3.Institute of Space Sciences, Shandong University, Weihai 264209, People’s Republic of China
4.Department of Physics, Brown University, Providence, RI 02912, USA
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GB/T 7714
Chiti,Anirudh,Mardini,Mohammad K.,Frebel,Anna,et al. The Metal-poor Metallicity Distribution of the Ancient Milky Way[J]. The Astrophysical Journal Letters,2021,911(2).
APA Chiti,Anirudh,Mardini,Mohammad K.,Frebel,Anna,&Daniel,Tatsuya.(2021).The Metal-poor Metallicity Distribution of the Ancient Milky Way.The Astrophysical Journal Letters,911(2).
MLA Chiti,Anirudh,et al."The Metal-poor Metallicity Distribution of the Ancient Milky Way".The Astrophysical Journal Letters 911.2(2021).
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