J/MNRAS/487/1462 The metal-rich halo tail extended in z (Fernandez-Alvar+, 2019)
The metal-rich halo tail extended in |z|:
a characterization with Gaia DR2 and APOGEE.
Fernandez-Alvar E., Fernandez-Trincado J.G., Moreno E., Schuster W.J.,
Carigi L., Recio-Blanco A., Beers T.C., Chiappini C., Anders F.,
Santiago B.X., Queiroz A.B.A., Perez-Villegas A., Zamora O.,
Garcia-Hernandez D.A., Ortigoza-Urdaneta M.
<Mon. Not. R. Astron. Soc., 487, 1462-1479 (2019)>
=2019MNRAS.487.1462F 2019MNRAS.487.1462F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, halo ; Abundances ; Milky Way ; Radial velocities ;
Proper motions ; Parallaxes, trigonometric ; Optical
Keywords: Galaxy: halo - Galaxy: disc - Galaxy: formation -
Galaxy: kinematics and dynamics - Galaxy: stellar content -
Stars: abundances
Abstract:
We report an analysis of the metal-rich tail ([Fe/H]>-0.75) of stars
located at distances from the Galactic plane up to |z|∼10kpc, observed
by the Apache Point Observatory Galactic Evolution Experiment
(APOGEE). We examine the chemistry, kinematics, and dynamics of this
metal-rich sample using chemical abundances and radial velocities
provided by the 14th APOGEE data release (DR14) and proper motions
from the second Gaia data release (DR2). The analysis reveals three
chemically different stellar populations in the [Mg/Fe] versus [Fe/H]
space - a high-[Mg/Fe] and low-[Mg/Fe] populations, and a third group
with intermediate [Mg/Fe]~+0.1 - as well as for other chemical
elements. We find that they are also kinematically and dynamically
distinct. The high-[Mg/Fe] population exhibits a prograde rotation
which decreases down to 0 as |zmax| increases, as well as eccentric
orbits that are more bound and closer to the plane. The low-[Mg/Fe]
stars are likely Sagittarius members, moving in less-bound orbits
reaching larger distances from the centre and the Galactic plane. The
intermediate-[Mg/Fe] stars resembles the two stellar overdensities
lying about |z|∼5kpc recently reported in the literature, for which a
disc origin has been claimed. We report the identification of new
members of these two disc-heated overdensities.
Description:
We select our sample of halo stars from the APOGEE DR14 (Abolfathi et
al. 2018ApJS..235...42A 2018ApJS..235...42A). This data release includes data from the
SDSS-III (Eisenstein et al. 2011AJ....142...72E 2011AJ....142...72E) APOGEE-1 program
(which comprises observations gathered from 2011 August to 2014 July -
see Zasowski et al. 2013AJ....146...81Z 2013AJ....146...81Z), as well as from the first
two years of SDSS-IV APOGEE-2 data (2014-2016 July - see Zasowski et
al. 2017AJ....154..198Z 2017AJ....154..198Z). Observations were taken using the Sloan
Foundation 2.5-m telescope (Gunn et al. 2006AJ....131.2332G 2006AJ....131.2332G) at Apache
Point observatory, and the APOGEE spectrograph (Wilson et al.
2010SPIE.7735E..1CW). Data for both programs were processed (Nidever
et al. 2015AJ....150..173N 2015AJ....150..173N), and chemical abundances and radial
velocities derived (Holtzman et al. 2015AJ....150..148H 2015AJ....150..148H), with the
APOGEE Stellar Spectra Parameter Pipeline (ASPCAP; Garcia-Perez et al.
2016AJ....151..144G 2016AJ....151..144G, Cat. J/AJ/151/144).
We choose field stars located at distances from the Galactic plane
larger than 5kpc. This selection cut aims to favour the selection of
halo against thick-disc stars. The coordinates, stellar parameters,
[Fe/H] and [Mg/Fe] abundances, as well as the radial velocities,
parallaxes, proper motions, and distance estimates for this sample are
shown in Tables A1 and A2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 95 504 Stellar parameters, [Fe/H] and [Mg/Fe]
abundances for our 504 halo candidates
tablea2.dat 89 504 Radial velocities, parallaxes, proper motions,
and distances for our 504 halo candidates
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Name Star name from APOGEE (2MHHMMSSss+DDMMSSs)
20- 26 F7.3 deg RAdeg Right ascension (J2000)
28- 34 F7.3 deg DEdeg Declination (J2000)
36- 42 F7.3 deg GLON Galactic longitude
44- 50 F7.3 deg GLAT Galactic latitude
52- 57 F6.1 K Teff Effective temperature
59- 63 F5.1 K e_Teff Error on Teff
65- 68 F4.2 [cm/s2] logg Surface gravity
70- 73 F4.2 [cm/s2] e_logg Error on logg
75- 79 F5.2 [-] [Fe/H] Iron to hydrogen abundance ratio
81- 84 F4.2 [-] e_[Fe/H] Error on [Fe/H]
86- 90 F5.2 [-] [Mg/Fe] Mg to iron abundance ratio
92- 95 F4.2 [-] e_[Mg/Fe] Error on [Mg/Fe]
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Name Star name from APOGEE (2MHHMMSSss+DDMMSSs)
20- 26 F7.2 km/s RV Radial velocity
28- 31 F4.2 km/s e_RV Error on RV
33- 39 F7.4 mas plx Parallax (1)
41- 46 F6.4 mas e_plx Error on parallax (1)
48- 54 F7.3 mas/yr pmRA Proper motion in right ascension (1)
56- 60 F5.3 mas/yr e_pmRA Error on pmRA (1)
62- 68 F7.3 mas/yr pmDE Proper motion in declination (1)
70- 74 F5.3 mas/yr e_pmDE Error on pmDE (1)
76- 82 F7.1 pc Dist Distance (2)
84- 89 F6.1 pc e_Dist Error on Dist (2)
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Note (1): Values from Gaia DR2 (Gaia Collaboration 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345)
Note (2): Distances were calculated by the SDSS Brazilian Participation Group
(BPG) using the STARHORSE code described in Santiago et al.
(2016A&A...585A..42S 2016A&A...585A..42S) and Queiroz et al. (2018MNRAS.476.2556Q 2018MNRAS.476.2556Q)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 09-Nov-2022