J/ApJ/743/176 BVI photometry of Cepheids in M81 (Gerke+, 2011)
A study of Cepheids in M81 with the Large Binocular Telescope (efficiently
calibrated with Hubble Space Telescope).
Gerke J.R., Kochanek C.S., Prieto J.L., Stanek K.Z., Macri L.M.
<Astrophys. J., 743, 176 (2011)>
=2011ApJ...743..176G 2011ApJ...743..176G
ADC_Keywords: Galaxies, nearby ; Photometry, HST ; Stars, variable
Keywords: distance scale - galaxies: distances and redshifts -
galaxies: individual (M81, NGC4258) - stars: variables: Cepheids -
techniques: image processing
Abstract:
We identify and phase a sample of 107 Cepheids with 10days<P<100days
in M81 (NGC 3031) using the Large Binocular Telescope and calibrate
their B, V, and I mean magnitudes with archival Hubble Space Telescope
(HST) data. The use of a ground-based telescope to identify and phase
the Cepheids and HST only for the final calibration reduces the demand
on this highly oversubscribed spacecraft by nearly an order of
magnitude and yields period-luminosity (PL) relations with dispersions
comparable to the best LMC samples. We fit the sample using the
OGLE-II LMC PL relations and are unable to find a self-consistent
distance for different band combinations or radial locations within
M81. We find a distance modulus for M81, relative to the LMC, of
µM81-µLMC=9.39±0.14mag, including uncertainties due to the
metallicity corrections. This corresponds to a distance to M81 of
3.6±0.2Mpc, assuming an LMC distance modulus of 18.41mag.
Description:
The galaxy M81 is being monitored as part of a ground-based
variability survey of nearby galaxies (Kochanek et al.
2008ApJ...684.1336K 2008ApJ...684.1336K) with the twin 8.4m Large Binocular Telescope
(LBT). The observations discussed here were taken with the Large
Binocular Camera (LBC)-Blue camera on 34 nights between 2007 January
and 2008 May. Some nights were subdivided to yield a total of 50
epochs in the V band.
The entire disk of M81 was imaged using HST/ACS and the F435W and
F606W filters (roughly equivalent to the B and V bands) by program
10584 (PI: Zezas) and the F814W filter (roughly equivalent to the I
band) by program 10250 (PI: Huchra). The HST images were acquired
between 2004 September and 2006 December.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 126 Cepheid parameters
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJ/734/L22 : ACS Nearby Galaxy Survey Treasury (Williams+, 2011)
J/ApJ/730/119 : HST/WFC3 observations of Cepheids in SN Ia (Riess+, 2011)
J/ApJ/715/277 : Insights into the Cepheid distance scale (Bono+, 2010)
J/A+A/504/959 : Amplitudes of single-mode Cepheids (Klagyivik+, 2009)
J/ApJ/699/539 : Cepheids in SN-Ia host galaxies (Riess+, 2009)
J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008)
J/other/A+ARV/15.289 : Distances of local galaxies (Tammann+, 2008)
J/A+A/411/361 : VI photometry of extra-galactic Cepheids (Kanbur+, 2003)
http://www.nearbygalaxies.org/ : ANGST (ACS Nearby Galaxy Survey Treasury)
home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [M81C]
6- 23 A18 --- M81C Cepheid identification (HHMMSS.ss+DDMMSS.s;
J2000) (1)
25- 30 F6.3 d Per [10/99] Period
32- 36 F5.2 mag Bmag Calibrated phase-averaged mean B-band magnitude
38- 42 F5.3 mag e_Bmag Bmag uncertainty
44- 48 F5.2 mag Vmag Calibrated phase-averaged mean V-band magnitude
50- 53 F4.2 mag e_Vmag Vmag uncertainty
55- 59 F5.2 mag Imag Calibrated phase-averaged mean I-band magnitude
61- 64 F4.2 mag e_Imag Imag uncertainty
66- 68 A3 --- F94 ID from Freedman et al. (2)
70- 74 A5 --- f_M81C Removed Cepheid from final sample (3)
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Note (1): The coordinates have errors ∼0.1". See section 2 for further details.
The Cepheids are <[GKP2011] M81C JHHMMSS.ss+DDMMSS.s> in Simbad.
Note (2): Identifier from Freedman et al. (1994ApJ...427..628F 1994ApJ...427..628F)
<[FHM94] CNN> in Simbad, for the Cepheids in common.
Note (3): Cepheids removed from the final sample are flagged as follows:
EX = extinction outside range;
AM = amplitude outside range;
CR = crowding parameter too large;
OU = outlier in Period-Luminosity relations.
D = Cepheids with two HST calibration observations
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 21-May-2013