J/AJ/159/46 Elemental abundances of 416 stars in 5 dSphs of M31 (Kirby+, 2020)
Elemental abundances in M31: the kinematics and chemical evolution of dwarf
spheroidal satellite galaxies.
Kirby E.N., Gilbert K.M., Escala I., Wojno J., Guhathakurta P.,
Majewski S.R., Beaton R.L.
<Astron. J., 159, 46 (2020)>
=2020AJ....159...46K 2020AJ....159...46K
ADC_Keywords: Abundances; Spectroscopy; Galaxies; Stars, giant;
Radial velocities; Photometry, VRI
Keywords: Andromeda Galaxy ; Dwarf galaxies ; Stellar abundances ; Local Group
Abstract:
We present deep spectroscopy from Keck/DEIMOS (DEep Imaging
Multi-Object Spectrograph) of Andromeda I, III, V, VII, and X, all of
which are dwarf spheroidal satellites (dSphs) of M31. The sample
includes 256 spectroscopic members across all five dSphs. We confirm
previous measurements of the velocity dispersions and dynamical
masses, and we provide upper limits on bulk rotation. Our measurements
confirm that M31 satellites obey the same relation between stellar
mass and stellar metallicity as Milky Way (MW) satellites and other
dwarf galaxies in the Local Group. The metallicity distributions show
trends with stellar mass that are similar to those of MW satellites,
including evidence in massive satellites for external influence, like
pre-enrichment or gas accretion. We present the first measurements of
individual element ratios, like [Si/Fe], in the M31 system, as well as
measurements of the average [α/Fe] ratio. The trends of
[α/Fe] with [Fe/H] also follow the same galaxy mass-dependent
patterns as MW satellites. Less massive galaxies have more steeply
declining slopes of [α/Fe] that begin at lower [Fe/H]. Finally,
we compare the chemical evolution of M31 satellites to M31's Giant
Stellar Stream and smooth halo. The properties of the M31 system
support the theoretical prediction that the inner halo is composed
primarily of massive galaxies that were accreted early. As a result,
the inner halo exhibits higher [Fe/H] and [α/Fe] than surviving
satellite galaxies.
Description:
Using the DEep Imaging Multi-Object Spectrograph (DEIMOS) at the Keck
observatory, Hawaii, in the fall seasons of 2015, 2016, and 2017, we
obtained spectroscopy (spectral range ∼6300-9100Å) of individual
red giants in five M31 dwarf spheroidal satellites (dSphs): Andromeda
VII, I, III, V, and X.
The deep spectroscopic slitmasks were designed using results from
slitmasks previously observed for approximately one hour as part of
the Spectroscopic Landscape of Andromeda's Stellar Halo survey
(SPLASH; e.g., Guhathakurta+ 2006AJ....131.2497G 2006AJ....131.2497G and Gilbert+
2009ApJ...705.1275G 2009ApJ...705.1275G and 2012ApJ...760...76G 2012ApJ...760...76G). The photometry used to
design slitmasks presented in this paper is exclusively from the
Mosaic imager at Kitt Peak National Observatory. The photometry was
obtained by Beaton (2014PhDT.......416B 2014PhDT.......416B) in the Washington system (M
and T2 filters), which we transformed to the Cousins system (V and I
filters) following Majewski+ (2000AJ....120.2550M 2000AJ....120.2550M). Images were also
obtained with the DDO51 filter. Table1 gives the data for each slitmask.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 20 DEep Imaging Multi-Object Spectrograph (DEIMOS)
observations
table2.dat 214 417 Catalog of abundances
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See also:
J/AJ/128/1177 : Galactic stellar abundances (Venn+, 2004)
J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)
J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007)
J/MNRAS/383/183 : CaII triplet of RGB from VLT/FLAMES obs. (Battaglia+, 2008)
J/ApJ/682/1217 : Abundances in red giants in 7 globular clusters (Kirby+,2008)
J/ApJ/705/328 : Abundance measurements in Sculptor dSph (Kirby+, 2009)
J/ApJ/706/599 : Hα and UV SFR in the local volume (Lee+, 2009)
J/ApJS/191/352 : Abundances stars of Milky Way dwarf satellites (Kirby+, 2010)
J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)
J/ApJ/751/46 : Spectroscopic observations in VV124 (UGC 4879) (Kirby+, 2012)
J/AJ/144/4 : Properties of dwarf galaxies Local Group (McConnachie+, 2012)
J/ApJ/752/45 : SPLASH: Stellar spectroscopy M31 satellites (Tollerud+, 2012)
J/ApJ/768/172 : Kinematic analysis of red giant in M31 dSphs (Collins+, 2013)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/A+A/572/A88 : Equivalent widths for Fornax RGB stars (Lemasle+, 2014)
J/ApJ/790/73 : Iron & alpha abundance RGBs in M31 satellites (Vargas+, 2014)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/ApJ/798/77 : Metallicity of RGB stars in 6 M31 dwarf galaxies (Ho+, 2015)
J/ApJ/833/167 : PAndAS view of Andromeda satellites. II. (Martin+, 2016)
J/MNRAS/465/4180 : Hα stars in M31 HST photometry (Prichard+, 2017)
J/ApJ/834/9 : Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal. (Kirby+,2017)
J/AJ/153/254 : Velocities RGB stars in Leo II dwarf galaxy (Spencer+, 2017)
J/ApJ/852/49 : Properties of metal-poor stars in APOGEE DR13 (Hayes+, 2018)
J/ApJS/235/36 : SPLASH-SXDF multi-wavelength photometric cat. (Mehta+, 2018)
J/A+A/626/A15 : Sculptor Red Giant Branch stars abundances (Hill+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- dSph Name of dwarf spheroidal galaxy
15- 20 A6 --- Mask Slitmask identification
22- 24 I3 --- Nslits [51/119] Number of slits for each slitmask
26- 28 F3.1 h Texp [4.6/6.7] Total exposure time
30- 32 I3 min Exp [20/206] Exposure time for each slitmask
34 I1 --- Nexp [1/8] Number of exposure per visit
36- 38 F3.1 arcsec Aper [0.5/1.1] Aperture
40- 43 I4 yr Obs.Y [2015/2017] UT year of observation
45- 47 A3 "month" Obs.M UT month of observation
49- 50 I2 d Obs.D UT day of observation
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- dSph Name of dwarf spheroidal galaxy
15- 21 I7 --- Name Star identification
23- 24 I2 h RAh [0/23] Hour of Right Ascension (J2000)
26- 27 I2 min RAm Minute of Right Ascension (J2000)
29- 33 F5.2 s RAs Second of Right Ascension (J2000)
35 A1 --- DE- [+] Sign of the Declination (J2000)
36- 37 I2 deg DEd [36/50] Degree of Declination (J2000)
39- 40 I2 arcmin DEm Arcminute of Declination (J2000)
42- 45 F4.1 arcsec DEs Arcsecond of Declination (J2000)
47- 51 F5.2 mag Vmag [21/26]?=0 Extinction-corrected apparent
Cousins V magnitude
53- 56 F4.2 mag e_Vmag [0.01/0.5]?=0 Uncertainty in Vmag
58- 62 F5.2 mag Imag [19.6/23]?=0 Extinction-corrected apparent
Cousins I magnitude
64- 67 F4.2 mag e_Imag [0.01/0.2]?=0 Uncertainty in Imag
69- 75 A7 --- Mask DEIMOS slitmask
77- 80 F4.1 0.1nm-1 SN [1.7/97] Signal-to-noise ratio per Angstrom
82- 88 F7.2 km/s HRV [-856/112]? Heliocentric radial velocity
90- 94 F5.2 km/s e_HRV [1.5/36]? Uncertainty in HRV
96 A1 --- Mm [N/Y] Member of galaxy; Y=yes (256 occurrences)
or N=no (161 occurrences)
98-101 I4 K Teff [3786/4991]? Effective temperature
103-105 I3 K e_Teff [10/117]? Uncertainty in Teff
107-110 F4.2 cm/s2 logg [0.3/1.6]? Surface gravity
112-116 F5.2 [Sun] [Fe/H] [-3.2/-0.59]? Iron abundance
118-121 F4.2 [Sun] e_[Fe/H] [0.1/0.39]? Uncertainty in [Fe/H]
123-127 F5.2 [Sun] [a/Fe] [-0.54/1.2]? Alpha-to-iron ratio [α/Fe]
129-132 F4.2 [Sun] e_[a/Fe] [0.12/0.39]? Uncertainty in [a/Fe]
134-138 F5.2 [Sun] [Mg/Fe] [0.39/1.2]? Magnesium-to-iron ratio
140-143 F4.2 [Sun] e_[Mg/Fe] [0.24/0.4]? Uncertainty in [Mg/Fe]
145-149 F5.2 [Sun] [Si/Fe] [-0.44/1.2]? Silicon-to-iron ratio
151-154 F4.2 [Sun] e_[Si/Fe] [0.18/0.4]? Uncertainty in [Si/Fe]
156-160 F5.2 [Sun] [Ca/Fe] [-0.4/1.2]? Calcium-to-iron ratio
162-165 F4.2 [Sun] e_[Ca/Fe] [0.21/0.39]? Uncertainty in [Ca/Fe]
167-171 F5.2 [Sun] [Ti/Fe] [-0.77/1.2]? Titanium-to-iron ratio
173-176 F4.2 [Sun] e_[Ti/Fe] [0.13/0.4]? Uncertainty in [Ti/Fe]
178-214 A37 --- Comm Comment on membership and spectral features
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 18-Mar-2020