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.
<Astrophys. J., 882, 177 (2019)>
=2019ApJ...882..177M 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 α-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 3310Å<λ<5000Å in the blue channel
(R∼41000) and 4830Å<λ<9160Å in the red (R∼32000).
File Summary:
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FileName Lrecl Records Explanations
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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
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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
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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 4200Å
74- 75 I2 --- SNR5500 [20/50] Signal-to-noise ratio at 5500Å
77- 80 A4 --- Loc Location
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Note (1): Astrometry and dereddened photometry from Li+ (2018, J/ApJ/866/22).
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Byte-by-byte Description of file: table2.dat
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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
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Byte-by-byte Description of file: table3.dat
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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
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Feb-2021