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J/ApJ/718/530          Leo IV g- and r-band photometry             (Sand+, 2010)

A deeper look at Leo IV: star formation history and extended structure. Sand D.J., Seth A., Olszewski E.W., Willman B., Zaritsky D., Kallivayalil N. <Astrophys. J., 718, 530-542 (2010)> =2010ApJ...718..530S
ADC_Keywords: Photometry, SDSS ; Galaxies, nearby ; Extinction ; Stellar distribution Keywords: galaxies: dwarf - Local Group Abstract: We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with ε<0.23 (at the 68% confidence limit) and a half-light radius of rh∼130pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness µr≲29.6mag/arcsec2, and at this limit we find no stellar bridge between Leo IV (out to a radius of ∼0.5kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age (∼14Gyr), single metallicity ([Fe/H]~-2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of MV=-5.5±0.3. Studying both the spatial distribution and frequency of Leo IV's "blue plume" stars reveals evidence for a young (∼2Gyr) stellar population which makes up ∼2% of its stellar mass. Description: We observed Leo IV on 2009 April 21 (UT) with Megacam on the MMT. We obtained 5250s dithered exposures in g and in r in clear conditions with 0.9" seeing. Precise astrometric solutions for each science exposure were derived using the Sloan Digital Sky Survey Data Release 6 (SDSS-DR6). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 61 25282 Leo IV photometry
See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/ApJ/710/1664 : BV photometry in Leo IV and Leo V dSphs (de Jong+, 2010) J/ApJS/191/352 : Abundances in stars of Milky Way dwarf satellites (Kirby+, 2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 I5 --- [SSO2010] [0/25281] Star index number 7- 15 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 17- 24 F8.5 deg DEdeg Declination in decimal degrees (J2000) 26- 30 F5.2 mag gmag The g band magnitude; uncorrected for extinction 32- 35 F4.2 mag e_gmag Uncertainty in gmag 37- 40 F4.2 mag Ag Galactic extinction value in g band 42- 46 F5.2 mag rmag The r band magnitude; uncorrected for extinction 48- 51 F4.2 mag e_rmag Uncertainty in rmag 53- 56 F4.2 mag Ar Galactic extinction value in r band 58- 61 A4 --- Ref Photometry source; SDSS or MMT
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Jun-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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