J/MNRAS/515/1469 Milky Way red clump bulge stars with BDBS (Johnson+, 2022)
Blanco DECam Bulge Survey (BDBS) IV. Metallicity distributions and bulge
structure from 2.6 million red clump stars.
Johnson C.I., Rich R.M., Simion I.T., Young M.D., Clarkson W.I.,
Pilachowski C.A., Michael S., Marchetti T., Soto M., Kunder A.,
Koch-Hansen A.J., Vivas A.K., Joyce M., Shen J., Osmond A.
<Mon. Not. R. Astron. Soc. 515, 1469-1491 (2022)>
=2022MNRAS.515.1469J 2022MNRAS.515.1469J (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, giant ; Stars, standard ; Galactic center ;
Positional data ; Photometry ; Optical ; Extinction ;
Stars, distances ; Abundances, [Fe/H]
Keywords: Galaxy: bulge
Abstract:
We present photometric metallicity measurements for a sample of 2.6
million bulge red clump stars extracted from the Blanco DECam Bulge
Survey (BDBS). Similar to previous studies, we find that the bulge
exhibits a strong vertical metallicity gradient, and that at least two
peaks in the metallicity distribution functions appear at b < -5°.
We can discern a metal-poor ([Fe/H] ∼ -0.3) and metal-rich ([Fe/H] ∼
+0.2) abundance distribution that each show clear systematic trends
with latitude, and may be best understood by changes in the bulge's
star formation/enrichment processes. Both groups exhibit asymmetric
tails, and as a result we argue that the proximity of a star to either
peak in [Fe/H] space is not necessarily an affirmation of group
membership. The metal- poor peak shifts to lower [Fe/H] values at
larger distances from the plane while the metal-rich tail truncates.
Close to the plane, the metal-rich tail appears broader along the
minor axis than in off-axis fields. We also posit that the bulge has
two metal-poor populations - one that belongs to the metal-poor tail
of the low latitude and predominantly metal-rich group, and another
belonging to the metal-poor group that dominates in the outer bulge.
We detect the X-shape structure in fields with |Z| > 0.7 kpc and for
stars with [Fe/H] > -0.5. Stars with [Fe/H] < -0.5 may form a
spheroidal or 'thick bar' distribution while those with [Fe/H] ~> -0.1
are strongly concentrated near the plane.
Description:
A new approach utilizing the u-i colour and the 3 deg2
field-of-view of the Dark Energy Camera was demonstrated to be an
efficient method for measuring [Fe/H] in large samples of bulge red
clump stars. The colour-metallicity relation provides the framework
for expanding the number of red clump stars with [Fe/H] measurements
from thousands to millions. Therefore, in this paper we exploit the
∼250 million star ugrizY catalogue spanning > 200 deg2 in the
Southern Galactic bulge provided by the Blanco DECam Bulge Survey to
extract metallicity and distance estimates for ∼2.6 million red clump
stars belonging to the Milky Way bulge. Next we use relation between
(u-i)0 and metallicity to compute [Fe/H] as well as its errors. The
results are provided in table1.dat containing positional, photometry
data used to compute distances and [Fe/H] values (i.e see all data
selection procedure in the section 2 & 3).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 2594412 Final red clump stars bulge members catalogue
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See also:
J/AJ/148/67 : Abundances of 156 bulge red giants (Johnson+, 2014)
J/ApJ/721/L28 : Red clump stars in Galactic Bulge from OGLE-III
(Nataf+, 2010)
J/ApJ/900/4 : Abundances and ages of stars in the Milky Way bulge
(Sit+, 2020)
J/ApJ/732/108 : Abundances of 92 giants in Plaut's window (Johnson+, 2011)
J/A+A/605/A89 : Abundances of microlensed Bulge dwarf stars. VI.
(Bensby+, 2017)
J/A+A/549/A147 : Abundances of microlensed bulge dwarf stars. V.
(Bensby+, 2013)
J/A+A/530/A54 : Abundances of 650 bulge red giants (Gonzalez+, 2011)
J/A+A/513/A35 : Abundances of Galactic red giants (Alves-Brito+, 2010)
J/A+A/559/A98 : JK photometry in BUL_SC9 and BUL_SC29 (Valenti+, 2013)
J/A+A/562/A66 : GIRAFFE Inner Bulge Survey (GIBS). I. (Zoccali+, 2014)
J/A+A/599/A12 : [Fe/H] and kinematics of 26 Galactic bulge fields
(Zoccali+, 2017)
J/A+A/653/A143 : A2A catalog of 21000 bulge stars from ARGOS survey
(Wylie+, 2021)
J/MNRAS/428/3660 : ARGOS line list λ8395-8830Å (Freeman+, 2013)
J/MNRAS/486/5349 : Chemical compositions of Galactic bulge stars (Duong+, 2019)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension (J2000) (RA)
11- 19 F9.5 deg DEdeg Declination (J2000) (DEC)
21- 26 F6.3 mag umag Apparent magnitude in CTIO/DECam u filter with
λmean = 3821Å (u)
28- 32 F5.3 mag e_umag Mean uncertainty of umag (uerr)
34- 39 F6.3 mag gmag Apparent magnitude in CTIO/DECam g filter with
λmean = 4862Å (g)
41- 45 F5.3 mag e_gmag Mean uncertainty of gmag (gerr)
47- 52 F6.3 mag imag Apparent magnitude in CTIO/DECam i filter with
λmean = 7850 Å (i)
54- 58 F5.3 mag e_imag Mean uncertainty of imag (ierr)
60- 65 F6.3 mag Au Extinction coefficient in CTIO/DECam u filter
(Au)
67- 72 F6.3 mag Ag Extinction coefficient in CTIO/DECam g filter
(Ag)
74- 79 F6.3 mag Ai Extinction coefficient in CTIO/DECam i filter
(Ai)
81- 86 F6.3 kpc D Star distance computed with the equation 7 of
the section 2 BDBS data selection (Dist.)
88- 92 F5.3 kpc e_D Mean σ propagated error of D
computed with equation 10 of the section 3.1
(σDist)
94- 98 F5.2 [Sun] [Fe/H] Iron to hydrogen abundance ratio computed with
colour-metallicity equation 8 of the section
3.1 ([Fe/H])
100-103 F4.2 [Sun] e_[Fe/H] Mean σ propagated error of [Fe/H]
computed with equation 9 of the section 3.1
(σ[Fe/H])
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History:
From electronic version of the journal
References:
Rich et al., Paper I 2020MNRAS.499.2340R 2020MNRAS.499.2340R
Johnson et al., Paper II 2020MNRAS.499.2357J 2020MNRAS.499.2357J
Lim et al., Paper III 2021A&A...647A..34L 2021A&A...647A..34L
Marchetti et al., Paper V 2022A&A...664A.124M 2022A&A...664A.124M
Kader et al., Paper VI 2023ApJ...950..126K 2023ApJ...950..126K
Kader et al., Paper VII 2022ApJ...940...76K 2022ApJ...940...76K
Marchetti et al., Paper VIII 2024A&A...682A..96M 2024A&A...682A..96M
(End) Luc Trabelsi [CDS] 16-Jun-2025