J/ApJ/888/31 HST/ACS observations and SFH of Antlia B (Hargis+, 2020)
Hubble Space Telescope imaging of Antlia B: star formation history and a new
tip of the red giant branch distance.
Hargis J.R., Albers S., Crnojevic D., Sand D.J., Weisz D.R., Carlin J.L.,
Spekkens K., Willman B., Peter A.H.G., Grillmair C.J., Dolphin A.E.
<Astrophys. J., 888, 31-31 (2020)>
=2020ApJ...888...31H 2020ApJ...888...31H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical; Photometry, HST
Keywords: Dwarf galaxies; Dwarf irregular galaxies; Star formation
Hubble Space Telescope
Abstract:
A census of the satellite population around dwarf galaxy primary hosts
in environments outside the Local Group is essential to understanding
Λ cold dark matter galaxy formation and evolution on the
smallest scales. We present deep optical Hubble Space Telescope
imaging of the gas-rich, faint dwarf galaxy Antlia B (MV=-9.4) --a
likely satellite of NGC 3109 (D=1.3Mpc)-- discovered as part of our
ongoing survey of primary host galaxies similar to the Magellanic
Clouds. We derive a new tip of the red giant branch distance of
D=1.35±0.06Mpc (m-M=25.65±0.10), consistent with membership in the
nearby NGC 3109 dwarf association. The color-magnitude diagram (CMD)
shows both a prominent old, metal-poor stellar component and confirms
a small population of young, blue stars with ages ≲1Gyr. We use the
CMD fitting algorithm MATCH to derive the star formation history (SFH)
and find that it is consistent with the typical dwarf irregular or
transitional dwarf galaxy (dTrans) in the Local Group. Antlia B shows
relatively constant stellar mass growth for the first ∼10-11Gyr and
almost no growth in the last ∼2-3Gyr. Despite being gas-rich, Antlia B
shows no evidence of active star formation (i.e., no Hα
emission) and should therefore be classified as a dTrans dwarf. Both
Antlia B and the Antlia dwarf (dTrans) are likely satellites of
NGC3109, suggesting that the cessation of ongoing star formation in
these galaxies may be environmentally driven. Future work studying the
gas kinematics and distribution in Antlia B will explore this scenario
in greater detail. Our work highlights the fact that detailed studies
of nearby dwarf galaxies in a variety of environments may continue to
shed light on the processes that drive the SFH and evolution of dwarf
galaxies more generally.
Description:
Observations of Antlia B were taken under HST program HST-GO-14078
(PI: J. Hargis) on 2017 January 4 with the Advanced Camera for Surveys
(ACS), using the Wide Field Channel.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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09 48 56.08 -25 59 24.0 Antlia B = NAME Antlia B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 156 7661 Photometry of resolved stars in the HST/ACS
imaging of Antlia B
table3.dat 30 51 Cumulative star formation history of Antlia B
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/A+A/566/A44 : gr photometry of Sextans A and Sextans B (Bellazzini+, 2014)
J/ApJ/843/16 : Galaxy groups within 3500km/s (Kourkchi+, 2017)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)
J/AJ/156/18 : APOGEE DR14: companions of evolved stars (Price-Whelan+, 2018)
J/AJ/116/2341 : UBVRI photometry in Sextans A (Van Dyk+ 1998)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID [79/58692] Object identification number
7- 17 F11.7 deg RAdeg [147.2/147.3] Right Ascension (J2000)
19- 29 F11.7 deg DEdeg [-26.1/-25.9] Declination (J2000)
31- 37 F7.2 pix Xpix HST/ACS X pixel coordinate
39- 45 F7.2 pix Ypix HST/ACS Y pixel coordinate
47- 49 F3.1 --- OType [1] DOLPHOT object type
51- 56 F6.3 mag F606Wmag [19/28] HST/ACS F606W band magnitude (1)
58- 62 F5.3 mag e_F606Wmag [0.001/0.3] Uncertainty in F606Wmag
64- 68 F5.1 --- SNR-F606W [5/801] Signal-to-Noise in F606W observation
70- 75 F6.3 --- Sh-F606W [-0.31/0.31] Sharp parameter value
in F606W observation
77- 82 F6.3 --- Rd-F606W [-0.45/3] Round parameter value
in F606W observation
84- 88 F5.3 --- C-F606W [0/0.7] Crowding parameter
in F606W observation
90- 92 F3.1 --- q_F606Wmag [0/3] Quality flag in F606Wmag (2)
94- 99 F6.3 mag F814Wmag [17.6/27.2] HST/ACS F814W band magnitude (1)
101-105 F5.3 mag e_F814Wmag [0.001/0.3] Uncertainty in F814Wmag
107-111 F5.1 --- SNR-F814W [5/946] Signal-to-Noise in F814W observation
113-118 F6.3 --- Sh-F814W [-0.31/0.31] Sharp parameter value
in F814W observation
120-125 F6.3 --- Rd-F814W [-0.5/3.5] Round parameter value
in F814W observation
127-131 F5.3 --- C-F814W [0/0.71] Crowding parameter
in F814W observation
133-135 F3.1 --- q_F814Wmag [0/3] Quality flag in F814Wmag (2)
137-142 F6.4 mag E(B-V) [0.08/0.082] Schlegel+ 1998ApJ...500..525S 1998ApJ...500..525S
(B-V) color excess
144-149 F6.4 mag AF606W [0.19/0.21] Milky Way extinction
in F606W band
151-156 F6.4 mag AF814W [0.122/0.125] Milky Way extinction
in F814W band
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Note (1): Not corrected for Milky Way extinction.
Note (2): The user should refer to the DOLPHOT documentation for the meaning
of the quality flags.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 [yr] log(t) [6.6/10.2] log epoch
7- 10 F4.2 --- f [0/1] Fraction of total stellar mass formed
prior to the corresponding epoch
12- 15 F4.2 --- sigRan84 [0/0.07] Upper 84% random uncertainty in f
17- 20 F4.2 --- sigRan16 [0/0.08] Lower 16% random uncertainty in f
22- 25 F4.2 --- sigTot84 [0/0.4] Upper 84% total uncertainty in f
27- 30 F4.2 --- sigTot16 [0/0.3] Lower 16% total uncertainty in f
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Jun-2021