J/AJ/166/180 Stellar population in Cassiopeia III and Perseus I (Rhode+, 2023)
Exploring the Structures and Substructures of the Andromeda Satellite Dwarf
Galaxies Cassiopeia III, Perseus I, and Lacerta I.
Rhode K.L., Smith N.J., Crnojevic D., Sand D.J., Lambert R.A.,
Vesperini E., Smith M.V., Janowiecki S., Salzer J.J., Karunakaran A.,
Spekkens K.
<Astron. J., 166, 180 (2023)>
=2023AJ....166..180R 2023AJ....166..180R
ADC_Keywords: Galaxies, dwarf; Populations, stellar; Photometry, VRI;
Extinction
Keywords: Dwarf galaxies ; Local Group ; Andromeda Galaxy ; Dwarf
spheroidal galaxies ; Sloan photometry ; Broad band photometry
; Galaxy stellar content ; Stellar populations
Abstract:
We present results from wide-field imaging of the resolved stellar
populations of the dwarf spheroidal galaxies CassiopeiaIII (AndXXXII)
and PerseusI (AndXXXIII), two satellites in the outer stellar halo of
the Andromeda galaxy (M31). Our WIYN pODI photometry traces the red
giant star population in each galaxy to ∼2.5-3 half-light radii from
the galaxy center. We use the tip of the red giant branch (TRGB)
method to derive distances of (m-M)0=24.62±0.12mag
(839-45+48kpc, or 156-13+16kpc from M31) for CasIII and
24.47±0.13mag (738-45+48kpc, or 351-16+17kpc from M31) for
Per I. These values are consistent within the errors with TRGB
distances derived from a deeper Hubble Space Telescope study of the
galaxies inner regions. For each galaxy, we derive structural
parameters, total magnitude, and central surface brightness. We also
place upper limits on the ratio of neutral hydrogen gas mass to
optical luminosity, confirming the gas-poor nature of both galaxies.
We combine our data set with corresponding data for the M31 satellite
galaxy LacertaI (AndXXXI) from earlier work and search for
substructure within the RGB star populations of CasIII, PerI, and Lac
I. We find an overdense region on the west side of Lac I at a
significance level of 2.5σ-3σ and a low-significance
filament extending in the direction of M31. In CasIII, we identify two
modestly significant overdensities near the center of the galaxy and
another at two half-light radii. PerI shows no evidence for
substructure in its RGB star population, which may reflect this
galaxy's isolated nature.
Description:
Observations of Cas III and Per I were obtained on 2013 October 2-3
and 2013 October 29-31, respectively, with the WIYN 3.5m telescope and
the One Degree Imager camera with a partially filled focal plane. The
field of view of the central imaging area in pODI was ∼24x24', with a
pixel scale of 0.11"/pixel. The galaxies were observed in the SDSS g
and i filters. Several 600-700s exposures were taken of each galaxy in
each filter over the course of the observing run.
Objects:
--------------------------------------------------------
RA (2000) DE Designation(s)
--------------------------------------------------------
00 35 59.39 +51 33 34.9 Cassiopeia III = NAME Cas III
03 01 23.59 +40 59 18.0 Perseus I = And XXXIII
--------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 28923 Catalog of resolved stars in the WIYN images of
Cas III
table2.dat 57 15263 Catalog of resolved stars in the WIYN images of
Per I
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See also:
J/ApJ/733/46 : Velocity measurements in Segue 1 (Simon+, 2011)
J/AJ/144/4 : Properties dwarf galaxies Local Group (McConnachie+, 2012)
J/ApJ/756/79 : Opt photometry in 3 Local Group dwarf galaxies (Sand+, 2012)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/MNRAS/439/1015 : Velocities red giants in 7 LG dwarf galaxies (Kirby+, 2014)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/ApJ/836/137 : Deep, wide-field g,i imaging of And XXXI (Rhode+, 2017)
J/ApJ/868/55 : Large-scale structure of M31 halo. II (McConnachie+, 2018)
J/ApJ/906/96 : Dwarfs galaxies in DC Justice League (Applebaum+, 2021)
J/ApJ/913/53 : Gas content of dwarf gal. within 2Mpc of MW (Putman+, 2021)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Sequential running number
7- 14 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 25 F10.6 deg DEdeg Declination in decimal degrees (J2000)
27- 31 F5.2 mag g0mag Calibrated, dereddened pODI/SDSS g band magnitude
33- 36 F4.2 mag e_g0mag Uncertainty in g0mag
38- 41 F4.2 mag Ag Caluculated Galactic extinction, g band
43- 47 F5.2 mag i0mag Calibrated, dereddened pODI/SDSS i band magnitude
49- 52 F4.2 mag e_i0mag Uncertainty in i0mag
54- 57 F4.2 mag Ai Caluculated Galactic extinction, i band
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 09-Apr-2024