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J/ApJ/838/11     Member stars in the MW satellite Tucana III     (Simon+, 2017)

Nearest neighbor: the low-mass Milky Way satellite Tucana III. Simon J.D., Li T.S., Drlica-Wagner A., Bechtol K., Marshall J.L., James D.J., Wang M.Y., Strigari L., Balbinot E., Kuehn K., Walker A.R., Abbott T.M.C., Allam S., Annis J., Benoit-Levy A., Brooks D., Buckley-Geer E., Burke D.L., Carnero Rosell A., Carrasco Kind M., Carretero J., Cunha C.E., D'Andrea C.B., da Costa L.N., Depoy D.L., Desai S., Doel P., Fernandez E., Flaugher B., Frieman J., Garcia-Bellido J., Gaztanaga E., Goldstein D.A., Gruen D., Gutierrez G., Kuropatkin N., Maia M.A.G., Martini P., Menanteau F., Miller C.J., Miquel R., Neilsen E., Nord B., Ogando R., Plazas A.A., Romer A.K., Rykoff E.S., Sanchez E., Santiago B., Scarpine V., Schubnell M., Sevilla-Noarbe I., Smith R.C., Sobreira F., Suchyta E., Swanson M.E.C., Tarle G., Whiteway L., Yanny B., (the DES Collaboration) <Astrophys. J., 838, 11-11 (2017)> =2017ApJ...838...11S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Radial velocities ; Equivalent widths ; Abundances, [Fe/H] ; Photometry, ugriz Keywords: dark matter; galaxies: dwarf; galaxies: individual: Tucana III; galaxies: stellar content; Local Group; stars: abundances Abstract: We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of vhel=-102.3±0.4(stat.)±2.0(sys.)km/s, a velocity dispersion of 0.1-0.1+0.7km/s, and a mean metallicity of [Fe/H]=-2.42-0.08+0.07. The upper limit on the velocity dispersion is σ<1.5km/s at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0x104M. We cannot rule out mass-to-light ratios as large as 240M/L for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V=15.7 that is the brightest known member star of an ultra-faint satellite. Description: We observed Tuc III with the IMACS spectrograph on the Magellan Baade telescope on five nights in 2015 July, one night in 2015 October, and four nights in 2016 August/September (resolution of R∼11000). All observations were obtained with a wide-band 5600-9200Å filter. We selected targets for spectroscopy using photometry from the Dark Energy Survey (DES) Year 2 quick release (Y2Q1) catalog (Drlica-Wagner+ 2015ApJ...813..109D). Objects: ---------------------------------------------------------------------- RA (ICRS) DE Designation(s) (Dist) ---------------------------------------------------------------------- 23 56 36 -59 36 00 Tucana III = NAME Tuc III (D=25kpc) ---------------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 105 151 Velocity and metallicity measurements for Tucana III (106 unique stars)
See also: VII/195 : Globular Clusters in the Milky Way (Harris, 1996) J/AJ/124/1144 : Orbits of 171 single-lined spectroscopic bin. (Latham, 2002) J/AJ/132/85 : Equivalent width of 33 metal-poor RHB (Preston+, 2006) J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006) J/A+A/465/357 : Stroemgren photometry in the Draco dSph galaxy (Faria+, 2007) J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007) J/MNRAS/411/1013 : CaII triplet in Sextans dSph galaxy (Battaglia+, 2011) J/ApJ/743/167 : Radial velocities and membership in Pal 13 (Bradford+, 2011) J/MNRAS/418/1526 : Dark matter in dSph galaxies (Charbonnier+, 2011) J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011) J/AJ/142/22 : Heavy-element dispersion in M92 (Roederer+, 2011) J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011) J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011) J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012) J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013) J/ApJ/770/16 : Spectroscopic members of Segue 2 galaxy (Kirby+, 2013) J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013) J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014) J/ApJ/801/74 : Dark matter profiles in dwarf galaxies (Geringer-Sameth+, 2015) J/ApJ/803/63 : gr photometry of stars in Kim 2 (Kim+, 2015) J/ApJ/808/95 : Spectroscopy of Reticulum II (Simon+, 2015) J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [DES] 4- 22 A19 --- DES Source identifier ( (1) 24- 30 F7.1 d MJD Modified Julian Date of the observation 32- 40 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 42- 50 F9.5 deg DEdeg Declination in decimal degrees (J2000) 52- 56 F5.2 mag gmag [16/22] DES dereddened g band magnitude (2) 58- 62 F5.2 mag rmag [15/22] DES dereddened r band magnitude (2) 64- 68 F5.1 --- S/N [2.5/181] Signal to Noise ratio 70- 76 F7.2 km/s HRV [-218/356] Heliocentric radial velocity 78- 82 F5.2 km/s e_HRV [1/12] Uncertainty in HRV 84- 87 F4.2 0.1nm EW [0.9/8]? CaT Equivalent width; Angstroms 89- 92 F4.2 0.1nm e_EW [0.3/2]? Uncertainty in EW 94- 98 F5.2 [Sun] [Fe/H] [-2.8/-1.9]? Metallicity 100-103 F4.2 [Sun] e_[Fe/H] [0.1/0.5]? Uncertainty in [Fe/H] 105 I1 --- Mm [0/1] Membership code (1=member (26 unique sources); 0=not a member)
Note (1): Some stars have multiple measurements made on different dates. These repeated measurements have been used to quantify systematic uncertainties (see Sections 3.1 and 3.2). Note (2): Quoted magnitudes represent the weighted-average dereddened PSF magnitude derived from the DES images using SExtractor (Drlica-Wagner+ 2015ApJ...813..109D).
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Oct-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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