J/ApJ/920/92 VLT Spectroscopy of Ultra-faint Dwarf Galaxies (Jenkins+, 2021)
Very Large Telescope Spectroscopy of Ultra-faint Dwarf Galaxies.
I. Bootes I, Leo IV, and Leo V.
Jenkins S.A., Li T.S., Pace A.B., Ji A.P., Koposov S.E., Mutlu-Pakdil B.
<Astrophys. J., 920, 92 (2021)>
=2021ApJ...920...92J 2021ApJ...920...92J
ADC_Keywords: Galaxies, dwarf; Spectra, infrared; Radial velocities
Keywords: Dwarf galaxies ; Local Group ; Stellar kinematics ; Dark
matter ; Stellar abundances ; Stellar populations ; Binary
stars ; Metallicity
Abstract:
We perform consistent reductions and measurements for three
ultra-faint dwarf galaxies (UFDs): Bootes I, Leo IV, and Leo V. Using
the public archival data from the GIRAFFE spectrograph on the Very
Large Telescope (VLT), we locate new members and provide refined
measurements of physical parameters for these dwarf galaxies. We
identify nine new Leo IV members and four new Leo V members, and
perform a comparative analysis of previously discovered members.
Additionally, we identify one new binary star in both Leo IV and Leo
V. After removing binary stars, we recalculate the velocity
dispersions of Bootes I and Leo IV to be 5.1-0.8+0.7 and
3.4-0.9+1.3km/s, respectively; we do not resolve the Leo V
velocity dispersion. We identify a weak velocity gradient in Leo V
that is ∼4x smaller than the previously calculated gradient and that
has a corresponding position angle that differs from the value in the
literature by ∼120°. Combining the VLT data with previous values
from the literature, we reanalyze the Bootes I metallicity
distribution function and find that a model including infall of
pristine gas, while Bootes I was forming stars' best fits the data.
Our analysis of Leo IV, Leo V, and other UFDs will enhance our
understanding of these enigmatic stellar populations and contribute to
future dark matter studies. This is the first in a series of papers
examining 13 UDFs observed with VLT/GIRAFFE between 2009 and 2017.
Similar analyses of the remaining 10 UFDs will be presented in
forthcoming papers.
Description:
We use the publicly available data from the ESO science archive
facility. 13 UFDs were observed by FLAMES/GIRAFFE between 2009 and
2017 using the LR8 grating and covering the wavelength range from
8206-9400Å at a spectral resolution of R∼6000.
Objects:
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RA (2000) DE Designation(s)
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14 00 00.00 +14 30 00.0 Bootes I = NAME Bootes I
11 32 57.00 +00 32 00.0 Leo IV = NAME Leo IV
11 31 09.59 +02 13 12.0 Leo V = NAME Leo V
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 106 327 Measurements of all observed stars in Bootes I,
Leo IV and Leo V
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/A+A/407/1157 : UVES sky atlas (Hanuschik+, 2003)
J/A+A/442/1127 : Library of 2500-10500Å synthetic spectra (Munari+, 2005)
J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)
J/MNRAS/380/281 : Faint galactic satellites spectroscopy (Martin+, 2007)
J/ApJ/692/1464 : Spectroscopy of Segue 1 (Geha+, 2009)
J/ApJ/694/L144 : Spectroscopic study of Leo V dSph (Walker+, 2009)
J/ApJ/710/1664 : BV photometry in Leo IV and Leo V dSphs (de Jong+, 2010)
J/ApJ/723/1632 : Abundance spreads in Bootes I and Segue 1 (Norris+, 2010)
J/MNRAS/411/1013 : CaII triplet in Sextans dSph galaxy (Battaglia+, 2011)
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011)
J/ApJ/756/79 : Opt photometry in 3 Local Group dwarf galaxies (Sand+, 2012)
J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015)
J/ApJ/808/108 : M2FS stellar spectroscopy of Reticulum 2 (Walker+, 2015)
J/ApJ/826/110 : Boo-127 and Boo-980 high-resolution spectra (Frebel+, 2016)
J/ApJ/819/53 : Magellan/M2FS spectroscopy of Tucana2 &Grus1 (Walker+, 2016)
J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018)
J/MNRAS/479/5343 : Nearby dwarf galaxy in Magellanic bridge (Koposov+, 2018)
J/ApJ/855/43 : Distant RR Lyrae stars discovered with HiTS (Medina+, 2018)
J/A+A/623/A129 : New satellites of the LMC search (Fritz+, 2019)
J/MNRAS/490/3508 : The Southern Stellar Stream Sp. Survey (S5) (Li+, 2019)
J/ApJ/885/53 : Spectro & HST photo of galaxy Leo V (Mutlu-Pakdil+, 2019)
J/AJ/159/46 : Elemental abundances 416 stars in 5 dSphs M31 (Kirby+, 2020)
J/A+A/635/A107 : Spectroscopy of the Eri 2 cluster (Zoutendijk+, 2020)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- ID Star identifier
11- 21 F11.7 deg RAdeg [172/211] Right Ascension (J2000)
23- 32 F10.7 deg DEdeg [-1/15] Declination (J2000)
34- 40 F7.2 --- S/N [0.4/1428] Signal-to-Noise ratio
42- 47 F6.1 km/s RVel [-804/507] Heliocentric radial velocity
49- 53 F5.1 km/s e_RVel [0.7/813] Uncertainty in RVel
55- 59 F5.2 0.1nm CaT [-1.47/52.76]? CaT equivalent width; see
Section 3 (in Å)
61- 65 F5.2 0.1nm e_CaT [0/18]? Uncertainty in CaT
67- 73 F7.2 0.1nm Mg [-400/7.08]? Mg equivalent width (in Å)
75- 79 F5.2 0.1nm e_Mg [0/82]? Uncertainty in Mg
81- 85 F5.3 --- GoodProb [0.15/1] Probabiblility of spectrum being
good quality (1)
87- 91 F5.3 --- MemProb [0/1]? Probability star is a member; Section 4
93- 97 F5.3 --- e_MemProb [0/1]? Lower uncertainty in MemProb
99-103 F5.3 --- E_MemProb [0/0.43]? Upper uncertainty in MemProb
105-106 I2 --- Member [-1/1] Subjective membership classification (2)
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Note (1): Calculated using a random forest classifier, see section 3.1.
Note (2): Classification as follows:
-1 = non-member star;
1 = member star.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Feb-2024