J/ApJ/766/20 HST photometry of star clusters in M82 (Lim+, 2013)
The star cluster system in the nearby starburst galaxy M82.
Lim S., Hwang N., Lee M.G.
<Astrophys. J., 766, 20 (2013)>
=2013ApJ...766...20L 2013ApJ...766...20L
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Photometry, HST
Keywords: galaxies: individual: M82; galaxies: irregular; galaxies: starburst;
galaxies: star clusters: general
Abstract:
We present a photometric study of star clusters in the nearby
starburst galaxy M82 based on the UBVI-, YJ- and H-band Hubble Space
Telescope images. We find 1105 star clusters with V<23mag. Of those,
1070 are located in the disk region, while 35 star clusters are in the
halo region. The star clusters in the disk are composed of a dominant
blue population with a color peak at (B-V)0∼0.45, and a weaker red
population. The luminosity function of the disk clusters shows a
power-law distribution with a power-law index α=-2.04±0.03,
and the scale height of their distribution is hz=9.64"±0.40"
(164±7pc), similar to that of the stellar thin disk of M82. We have
derived the ages of ∼630 star clusters using the spectral energy
distribution fit method by comparing UBVI(YJ)H-band photometric data
with the simple stellar population models. The age distribution of the
disk clusters shows that the most dominant cluster population has ages
ranging from 100Myr to 1Gyr, with a peak at about 500Myr. This
suggests that M82 has undergone a disk-wide star formation about
500Myr ago, probably through the interaction with M81. The brightest
star clusters in the nuclear region are much brighter than those in
other regions, indicating that more massive star clusters are formed
in the denser environments. On the other hand, the colors of the halo
clusters are similar to those of globular clusters in the Milky Way,
and their ages are estimated to be older than 1Gyr. These are probably
genuine old globular clusters in M82.
Description:
In this study, we present a survey of the star clusters in M82
(NGC3034) using high-resolution optical and near-infrared (U to H)
images taken with HST/ACS Wide Field Channel (WFC; proposal ID 10776;
F435W, F555W, and F814W filters (B,V, and I) and HST/Wide Field Camera
3 (WFC3; proposal ID 11360; F336W (U), F110W (YJ), and F160W (H)
bands), covering not only the disk but also some halo area in M82. The
FWHM of a point source in NIR images is about 0.25". We adopt a
distance to M82 of 3.55Mpc ((m-M)0=27.75±0.07) determined from the
measurement of the I-band magnitude of the tip of the red giant branch
magnitude (M. G. Lee et al. 2013ApJ...773...13L 2013ApJ...773...13L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 125 1105 A catalog of the star clusters in M82
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
VI/96 : Evolutionary Sequences (Fagotto+ 1993-96)
J/A+A/532/A147 : HST photometry in extragalactic star clusters (Larsen+, 2011)
J/ApJ/734/L22 : ACS Nearby Galaxy Survey Treasury (Williams+, 2011)
J/ApJ/679/404 : Star clusters in M82 (Mayya+, 2008)
J/ApJ/667/L145 : HST Photometry of M82 region B (Smith+, 2007)
J/ApJ/619/270 : Young super star clusters in M82 starburst (Melo+, 2005)
J/AJ/121/768 : BVIJH photometry of M82 (de Grijs+, 2001)
J/A+AS/139/393 : Young Massive Star Clusters. II. (Larsen, 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [1/1105] Object ID number
7- 8 I2 h RAh [9] Hour of Right ascension (J2000)
10- 11 I2 min RAm [55/56] Minute of Right ascension (J2000)
13- 17 F5.2 s RAs Second of Right ascension (J2000)
19 A1 --- DE- [+] Sign of Declination (J2000)
20- 21 I2 deg DEd [69] Degree of Declination (J2000)
23- 24 I2 arcmin DEm [36/45] Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
31- 36 F6.3 mag Vmag [16/23] HST/ACS F555W magnitude (1)
38- 43 F6.3 mag e_Vmag [0.002/0.4] Uncertainty in V-band magnitude
45- 50 F6.3 mag (B-V) ?=99.999 F435W-F555W color index (1)
52- 57 F6.3 mag e_(B-V) ?=99.999 Uncertainty in (B-V)
59- 64 F6.3 mag (V-I) ?=99.999 F555W-F814W color index (1)
66- 71 F6.3 mag e_(V-I) ?=99.999 Uncertainty in (V-I)
73- 78 F6.3 mag (U-B) ?=99.999 F336W-F435W color index (1)
80- 85 F6.3 mag e_(U-B) ?=99.999 Uncertainty in (U-B)
87- 92 F6.3 mag (I-YJ) ?=99.999 F814W-F110W color index (1)
94- 99 F6.3 mag e_(I-YJ) ?=99.999 Uncertainty in (I-YJ)
101-106 F6.3 mag (YJ-H) ?=99.999 F110W-F160W color index (1)
108-113 F6.3 mag e_(YJ-H) ?=99.999 Uncertainty in (YJ-H)
115-119 F5.2 pc reff [0.01/61]?=99.99 Effective radius
(adopted distance = 3.55Mpc)
121-125 F5.2 [yr] logA [6/10.3]?=99.99 Log of cluster age
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Note (1): F555W magnitude is aperture corrected; the colots are correspond to
an aperture radius of 0.35arcsec.
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History:
* 12-Nov-2014: from electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Nov-2014