J/ApJ/935/L17 Magellan IMACS color-magnitude diagram for Tucana B (Sand+, 2022)
Tucana B: A Potentially Isolated and Quenched Ultra-faint Dwarf Galaxy at.
Sand D.J., Mutlu-Pakdil B., Jones M.G., Karunakaran A., Wang F., Yang J.,
Chiti A., Bennet P., Crnojevic D., Spekkens K.
<Astrophys. J., 935, L17 (2022)>
=2022ApJ...935L..17S 2022ApJ...935L..17S
ADC_Keywords: Galaxies, dwarf; Photometry, VRI
Keywords: Dwarf galaxies ; Quenched galaxies ; Galaxy quenching
Abstract:
We report the discovery of Tucana B, an isolated ultra-faint dwarf
galaxy at a distance of D=1.4Mpc. Tucana B was found during a search
for ultra-faint satellite companions to the known dwarfs in the
outskirts of the Local Group, although its sky position and distance
indicate the nearest galaxy to be ∼500kpc distant. Deep ground-based
imaging resolves TucanaB into stars, and it displays a sparse red
giant branch consistent with an old, metal-poor stellar population
analogous to that seen in the ultra-faint dwarf galaxies of the Milky
Way, albeit at fainter apparent magnitudes. TucanaB has a half-light
radius of 80±40pc and an absolute magnitude of
MV=-6.9-0.6+0.5mag (LV=(5-2+4)x104L☉), which is
again comparable to the Milky Way's ultra-faint satellites. There is
no evidence for a population of young stars, either in the optical
color-magnitude diagram or in GALEX archival ultraviolet imaging, with
the GALEX data indicating logSFRNUV/M☉/yr)←5.4 for star
formation on ∼100Myr timescales. Given its isolation and physical
properties, TucanaB may be a definitive example of an ultra-faint
dwarf that has been quenched by reionization, providing strong
confirmation of a key driver of galaxy formation and evolution at the
lowest mass scales. It also signals a new era of ultra-faint dwarf
galaxy discovery at the extreme edges of the Local Group.
Description:
Deep g- and r-band imaging was taken with the Inamori-Magellan Areal
Camera & Spectrograph (IMACS) on 2021 December 03 (UT). We used the
f/2 camera, which delivers a ∼27.4' field of view and 0.2"/pixel
scale. Observations were taken in the g (4x300s) and r (3x300s)
bands, with small dithers between exposures.
Objects:
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RA (ICRS) DE Designation(s)
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22 47 00.49 -58 24 26.9 Tucana B = NAME Tucana B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2.dat 44 268 The color-magnitude diagram of Tucana B from our
Magellan IMACS data
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See also:
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
J/A+A/315/40 : Photometry of the Tuc dwarf galaxy (Saviane, 1996)
J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)
J/ApJS/164/38 : UV & FIR properties nearby galaxies (Iglesias-Paramo+, 2006)
J/ApJ/699/1742 : LCID project. I. Cetus and Tucana variables (Bernard+, 2009)
J/ApJ/704/898 : Photometry of the Hercules dwarf galaxy (Sand+, 2009)
J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011)
J/AJ/144/4 : Properties of dwarf galaxies Local Group (McConnachie+, 2012)
J/ApJ/756/79 : Optical photometry 3 Local Group dwarf galaxies (Sand+, 2012)
J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013)
J/AJ/145/149 : ALFALFA discovery of Leo P. II. BVR photometry (Rhode+, 2013)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/A+A/578/A61 : Galaxy groups in the 2M++ (Diaz-Gimenez+, 2015)
J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)
J/ApJ/806/95 : A search for ultra-compact HVC counterparts (Sand+, 2015)
J/ApJ/827/89 : HST imaging of Pisces A and B (Tollerud+, 2016)
J/ApJ/891/144 : CFHT dwarf satellite galaxies around LV host (Carlsten+, 2020)
J/ApJ/888/31 : HST/ACS observations and SFH of Antlia B (Hargis+, 2020)
J/ApJ/909/211 : HST obs. of MADCASH-1 and MADCASH-2 (Carlin+, 2021)
J/ApJ/916/L19 : Satellites around MW analogs from SAGA II (Karunakaran+, 2021)
J/ApJ/907/85 : SAGA Survey II. Satellite systems around galaxies (Mao+, 2021)
J/ApJ/913/53 : Gas content of dwarf gal within 2Mpc of the MW (Putman+, 2021)
J/ApJ/908/18 : HST stellar photometry of Eridanus II (Simon+, 2021)
Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg [341/342] Right Ascension in decimal degrees (J2000)
11- 20 F10.6 deg DEdeg [-59/-58] Declination in decimal degrees (J2000)
22- 26 F5.2 mag gmag [21.5/27] Apparent g-band AB magnitude (1)
28- 32 F5.2 mag rmag [21/26.7] Apparent r-band AB magnitude (1)
34- 44 A11 --- ID Panel identifier (2)
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Note (1): Extinction corrected.
Note (2): The panel in Figure 2 the data comes from. 'TucanaB' is from the
first two panels (which display identical data), 'Background1'
corresponds to the first panel labeled 'Background' in the figure,
while 'Background2' corresponds to the second 'Background' panel.
The backgrounds are randomly selected equal area regions.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 10-Jun-2024