J/AJ/146/145 ALFALFA discovery of Leo P. IV. VI photometry (Mcquinn+, 2013)
ALFALFA discovery of the nearby gas-rich dwarf galaxy Leo P.
IV. Distance measurement from LBT optical imaging.
McQuinn K.B.W., Skillman E.D., Berg D., Cannon J.M., Salzer J.J.,
Adams E.A.K., Dolphin A., Giovanelli R., Haynes M.P., Rhode K.L.
<Astron. J., 146, 145 (2013)>
=2013AJ....146..145M 2013AJ....146..145M
ADC_Keywords: Galaxies, nearby ; Photometry, VRI
Keywords: galaxies: distances and redshifts - galaxies: dwarf -
galaxies: evolution - galaxies: fundamental parameters -
galaxies: photometry - galaxies: stellar content
Abstract:
Leo P is a low-luminosity dwarf galaxy discovered through the blind HI
Arecibo Legacy Fast ALFA survey. The HI and follow-up optical
observations have shown that Leo P is a gas-rich dwarf galaxy with
both active star formation and an underlying older population, as well
as an extremely low oxygen abundance. Here, we measure the distance to
Leo P by applying the tip of the red giant branch (TRGB) distance
method to photometry of the resolved stellar population from new Large
Binocular Telescope V and I band imaging. We measure a distance
modulus of 26.19+0.17-0.50mag corresponding to a distance of
1.72+0.140.40Mpc. Although our photometry reaches 3mag below the
TRGB, the sparseness of the red giant branch yields higher
uncertainties on the lower limit of the distance. Leo P is outside the
Local Group with a distance and velocity consistent with the local
Hubble flow. While located in a very low-density environment, Leo P
lies within ∼0.5Mpc of a loose association of dwarf galaxies which
include NGC 3109, Antlia, Sextans A, and Sextans B, and 1.1Mpc away
from its next nearest neighbor, Leo A. Leo P is one of the lowest
metallicity star-forming galaxies known in the nearby universe,
comparable in metallicity to I Zw 18 and DDO 68, but with stellar
characteristics similar to dwarf spheriodals (dSphs) in the Local
Volume such as Carina, Sextans, and Leo II. Given its physical
properties and isolation, Leo P may provide an evolutionary link
between gas-rich dwarf irregular galaxies and dSphs that have fallen
into a Local Group environment and been stripped of their gas.
Description:
Deep optical observations in the Bessel V and I band filters were
obtained with the LBT at the Mt. Graham Observatory using the Large
Binocular Cameras (LBC) on the UT date of 2012 November 23. The LBT
uses two 8.4m diameter primary mirrors with adaptive optics. The
magnitudes were transformed to Johnson V and I magnitudes using the
conversion from Lupton provided on the SDSS Web site
(http://www.sdss.org/dr5/algorithms/sdssUBVRITransform.html).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 50 438 LBT (Large Binocular Telescope) catalog of
resolved stars in Leo P
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See also:
J/AJ/145/149 : ALFALFA discovery of Leo P. II. BVR photometry (Rhode+, 2013)
J/AJ/142/170 : ALFALFA survey: the α.40 HI source catalog (Haynes+, 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Star [1/438] Running index number identifier
<[MSB2013] NNN> in Simbad
5- 6 I2 h RAh Hour of Right Ascension (J2000)
8- 9 I2 min RAm Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- Sign of the Declination (J2000)
18- 19 I2 deg DEd Degree of Declination (J2000)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000)
24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000)
30- 34 F5.2 mag Vmag Intrinsic V band magnitude
36- 39 F4.2 mag e_Vmag The 1σ error in Vmag
41- 45 F5.2 mag Imag Intrinsic I band magnitude
47- 50 F4.2 mag e_Imag The 1σ error in Imag
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History:
From electronic version of the journal
References:
Giovanelli et al., Paper I., 2013AJ....146...15G 2013AJ....146...15G
McQuinn et al., Paper II., 2013AJ....145..149R 2013AJ....145..149R, Cat. J/AJ/145/149
Skillman et al., Paper III., 2013AJ....146....3S 2013AJ....146....3S
Bernstein-Cooper et al., Paper V.,
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 23-Jul-2014