J/ApJ/882/177 Abundances of 4 member stars of Tucana III (Marshall+, 2019) ================================================================================ Chemical abundance analysis of Tucana III, the second r-process enhanced ultra-faint dwarf galaxy. Marshall J.L., Hansen T., Simon J.D., Li T.S., Bernstein R.A., Kuehn K., Pace A.B., DePoy D.L., Palmese A., Pieres A., Strigari L., Drlica-Wagner A., Bechtol K., Lidman C., Nagasawa D.Q., Bertin E., Brooks D., Buckley-Geer E., Burke D.L., Rosell A.C., Kind M.C., Carretero J., Cunha C.E., D'Andrea C.B., da Costa L.N., De Vicente J., Desai S., Doel P., Eifler T.F., Flaugher B., Fosalba P., Frieman J., Garcia-Bellido J., Gaztanaga E., Gerdes D.W., Gruendl R.A., Gschwend J., Gutierrez G., Hartley W.G., Hollowood D.L., Honscheid K., Hoyle B., James D.J., Kuropatkin N., Maia M.A.G., Menanteau F., Miller C.J., Miquel R., Plazas A.A., Sanchez E., Santiago B., Scarpine V., Schubnell M., Serrano S., Sevilla-Noarbe I., Smith M., Soares-Santos M., Suchyta E., Swanson M.E.C., Tarle G., Wester W. =2019ApJ...882..177M ================================================================================ ADC_Keywords: Abundances, [Fe/H]; Equivalent widths; Radial velocities; Spectra, optical Keywords: Chemical abundances ; Chemically peculiar stars ; Dwarf galaxies Abstract: We present a chemical abundance analysis of four additional confirmed member stars of Tucana III, a Milky Way satellite galaxy candidate in the process of being tidally disrupted as it is accreted by the Galaxy. Two of these stars are centrally located in the core of the galaxy while the other two stars are located in the eastern and western tidal tails. The four stars have chemical abundance patterns consistent with the one previously studied star in Tucana III: they are moderately enhanced in r-process elements, i.e., they have <[Eu/Fe]>~+0.4dex. The non-neutron-capture elements generally follow trends seen in other dwarf galaxies, including a metallicity range of 0.44 dex and the expected trend in {alpha}-elements, i.e., the lower metallicity stars have higher Ca and Ti abundances. Overall, the chemical abundance patterns of these stars suggest that Tucana III was an ultra-faint dwarf galaxy, and not a globular cluster, before being tidally disturbed. As is the case for the one other galaxy dominated by r-process enhanced stars, Reticulum II, Tucana III's stellar chemical abundances are consistent with pollution from ejecta produced by a binary neutron star merger, although a different r-process element or dilution gas mass is required to explain the abundances in these two galaxies if a neutron star merger is the sole source of r-process enhancement. Description: Observations of the four confirmed member stars in the Tuc III stellar system were performed with the MIKE spectrograph at the Magellan-Clay Telescope at Las Campanas Observatory. Observations took place on 2016 August 5-7. The spectra cover 3310{AA}<{lambda}<5000{AA} in the blue channel (R~41000) and 4830{AA}<{lambda}<9160{AA} in the red (R~32000). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 80 5 Observing log table2.dat 59 5 Measured stellar parameters table3.dat 53 536 FeI and FeII lines used for parameter determination -------------------------------------------------------------------------------- See also: II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018) VII/195 : Globular Clusters in the Milky Way (Harris, 1996) VII/202 : Globular Clusters in the Milky Way (Harris, 1997) J/A+A/381/500 : Eu abundances in F and G disk stars (Koch+, 2002) J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004) J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005) J/A+A/455/271 : Abundances of red giants in NGC 6441 (Gratton+, 2006) J/A+A/464/967 : Abundances of red giants in NGC 6388 (Carretta+, 2007) J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009) J/ApJ/708/560 : Spectroscopy of UMa II and Coma Ber (Frebel+, 2010) J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010) J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011) J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013) J/ApJ/763/61 : Abundances of 7 red giant members of BootesI (Gilmore+, 2013) J/ApJ/770/16 : Spectroscopic members of Segue 2 galaxy (Kirby+, 2013) J/ApJ/786/74 : EW measurements of 6 Segue 1 red giants (Frebel+, 2014) J/A+A/562/A146 : Chemical abundances of 8 metal-poor stars (Ishigaki+, 2014) J/MNRAS/440/2665 : SDSS J021933.13+200830.2 spectroscopy (Roederer+, 2014) J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014) 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/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/830/93 : Abundances of Ret II brightest red giant members (Ji+, 2016) J/ApJ/817/41 : Abundances of 4 metal-poor red giants in BooII (Ji+, 2016) J/AJ/151/82 : 4 bright red giants in the UFD galaxy Ret 2 (Roederer+, 2016) J/ApJ/838/44 : Abundances of the brightest member of Tuc III (Hansen+, 2017) J/ApJ/838/83 : RVs, abundances & membership in TriII (Kirby+, 2017) J/ApJ/838/11 : Member stars in the MW satellite Tucana III (Simon+, 2017) J/ApJ/857/74 : Abundances of 7 new member stars in Tucana II (Chiti+, 2018) J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018) J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018) J/ApJ/857/145 : MagLiteS Carina II and Carina III spectroscopy (Li+, 2018) J/ApJ/852/99 : Abundances of 3 metal-poor stars in Hor I (Nagasawa+, 2018) J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018) J/ApJ/863/89 : Gaia DR2 PMs in ultra-faint MW satellites (Simon, 2018) J/ApJ/870/83 : Abundances in ultra-faint dwarf gal. GruI & TriII (Ji+, 2019) J/ApJ/875/77 : Proper motions of MW satellites with Gaia & DES (Pace+, 2019) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 A3 --- --- [DES] 5- 18 A14 --- Name Star name (DES JHHMMSS+DDMMSS) 20 A1 --- f_Name c: from Hansen+ (2017, J/ApJ/838/44), included for reference 22- 23 I2 h RAh Hour of right ascension (J2000) (1) 25- 26 I2 min RAm Minute of right ascension (J2000) 28- 31 F4.1 s RAs Second of right ascension (J2000) 33 A1 --- DE- Sign of declination (J2000) (1) 34- 35 I2 deg DEd Degree of declination (J2000) (1) 37- 38 I2 arcmin DEm Arcminute of declination (J2000) 40- 43 F4.1 arcsec DEs Arcsecond of declination (J2000) 45- 50 F6.3 mag gmag [16/17.7] g-band magnitude (1) 52- 56 F5.3 mag g-r [0.5/0.8] g-r colour index (1) 58- 65 F8.2 d MJD [57248/57607.8] Modified Julian Date, at the midpoint of the observation 67- 69 F3.1 h Exp [2/4.5] Exposure time 71- 72 I2 --- SNR4200 [10/30] Signal-to-noise ratio at 4200{AA} 74- 75 I2 --- SNR5500 [20/50] Signal-to-noise ratio at 5500{AA} 77- 80 A4 --- Loc Location -------------------------------------------------------------------------------- Note (1): Astrometry and dereddened photometry from Li+ (2018, J/ApJ/866/22). -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 A3 --- --- [DES] 5- 11 A7 --- ID Abbreviated identifier (JHHMMSS) 13- 18 F6.1 km/s HRV [-121.5/-92.6] Heliocentric radial velocity 20- 22 F3.1 km/s e_HRV [0.3/1.1] HRV uncertainty 24- 27 I4 K Teff [4675/4900] Effective temperature 29- 31 I3 K e_Teff [100/150] Teff uncertainty 33- 36 F4.2 [cm/s2] logg [1.3/1.9] Log of surface gravity 38- 40 F3.1 [cm/s2] e_logg [0.3] Logg uncertainty 42- 44 F3.1 km/s Vt [1.3/2] Microturbulent velocity 46- 48 F3.1 km/s e_Vt [0.3] Vt uncertainty 50- 54 F5.2 [Sun] [Fe/H] [-2.7/-2.2] Log of Fe/ abundance 56- 59 F4.2 [Sun] e_[Fe/H] [0.08/0.2] [Fe/H] uncertainty -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 14 A14 --- Name Tucana III star name 16- 19 A4 --- Ion Atomic species of absorption feature (FeI or FeII) 21- 27 F7.2 0.1nm lambda [3765.54/8824.22] Rest wavelength of absorption feature 29- 33 F5.3 eV chi [0/4.6] Excitation potential of absorption line 35- 40 F6.3 [-] loggf [-4.8/0.65] Oscillator strength of absorption line 42- 47 F6.2 0.1pm EW [6/110] Measured equivalent width of absorption line 49- 53 F5.3 [-] loge [4.2/5.4] Measured chemical abundance from absorption feature -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Feb-2021