J/ApJ/836/137 Deep, wide-field g,i imaging of And XXXI (Rhode+, 2017)
Structural and photometric properties of the Andromeda satellite dwarf galaxy
Lacerta I from deep imaging with WIYN pODI.
Rhode K.L., Crnojevic D., Sand D.J., Janowiecki S., Young M.D., Spekkens K.
<Astrophys. J., 836, 137-137 (2017)>
=2017ApJ...836..137R 2017ApJ...836..137R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, SDSS
Keywords: galaxies: dwarf; galaxies: individual: (Lac I, And XXXI);
galaxies: photometry; Local Group
Abstract:
We present results from WIYN pODI imaging of Lacerta I (And XXXI), a
satellite dwarf galaxy discovered in the outskirts of the Andromeda
galaxy (M31) in Pan-STARRS1 survey data. Our deep, wide-field g,i
photometry reaches ∼3mag fainter than the photometry in the
Pan-STARRS1 discovery paper and allows us to trace the stellar
population of Lac I beyond two half-light radii from the galaxy
center. We measure a Tip of the Red Giant Branch distance for Lac I of
(m-M)0=24.44±0.11mag (773±40kpc, or 264±6kpc from M31), which
is consistent with the Pan-STARRS1 distance. We use a
maximum-likelihood technique to derive structural properties for the
galaxy, and find a half-light radius (rh) of 3.24±0.21'
(728±47pc), ellipticity (ε) of 0.44±0.03, total magnitude
MV=-11.4±0.3, and central surface brightness
µV,0=24.8±0.3mag/arcsec2. We find no H I emission in archival
data and set a limit on Lac I's neutral gas mass-to-light ratio of
MHI/LV<0.06M☉/L☉, confirming Lac I as a gas-poor dwarf
spheroidal galaxy. Photometric metallicities derived from Red Giant
Branch stars within 2 rh yield a median [Fe/H] of -1.68±0.03,
which is more metal-rich than the spectroscopically derived value from
Martin+ (2014ApJ...793L..14M 2014ApJ...793L..14M). Combining our measured magnitude with
this higher metallicity estimate places Lac I closer to its expected
position on the luminosity-metallicity relation for dwarf galaxies.
Description:
Observations of Lac I (And XXXI) were obtained on 2013 October 1 with
the WIYN 3.5m telescope and the One Degree Imager with a partially
filled focal plane (pODI). The mean FWHM of the point-spread function
(PSF) in the final combined images is 0.84" in the g-band and 0.70" in
the i-band.
Objects:
----------------------------------------------------------------
RA (ICRS) DE Designation(s) (Distance)
----------------------------------------------------------------
22 58 13.2 +41 17 53 Lac I = NAME Lacerta I (D=773kpc)
----------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 58 33577 Photometry of resolved stars in the WIYN pODI images
of Lac I (And XXXI)
--------------------------------------------------------------------------------
See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/756/79 : Optical photom. in 3 Local Group dwarf galaxies (Sand+, 2012)
J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013)
J/ApJ/779/102 : Metallicities of RGB stars in dwarf galaxies (Kirby+, 2013)
J/MNRAS/435/1928 : Dwarf galaxy planes in Local Group (Pawlowski+, 2013)
J/A+A/585/A41 : EBHIS spectra and HI column density maps (Winkel+, 2016)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Seq Sequential running number
7- 15 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
17- 26 F10.6 deg DEdeg Declination in decimal degrees (J2000)
28- 32 F5.2 mag g0mag [13/27] Calibrated, dereddened WIYN/pODI
g band magnitude in SDSS system
34- 37 F4.2 mag e_g0mag [0/0.4] Uncertainty (instrumental) in g0mag
39- 42 F4.2 mag Ag [0.3/0.6] Calculated Galactic extinction, g mag
44- 48 F5.2 mag i0mag [13/26.2] Calibrated, dereddened WIYN/pODI
i band magnitude in SDSS system
50- 53 F4.2 mag e_i0mag [0/0.4] Uncertainty (instrumental) in i0mag
55- 58 F4.2 mag Ai [0.1/0.3] Calculated Galactic extinction, i mag
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Sep-2017