J/A+A/649/A138 Intensity profiles for GC1 of M81 (Wang+, 2021)
Properties of the brightest globular cluster in M81 based on
multicolour observations.
Wang S., Ma J.
<Astron. Astrophys. 649, A138 (2021)>
=2021A&A...649A.138W 2021A&A...649A.138W (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Photometry, surface ;
Photometry, HST
Keywords: galaxies: evolution -
galaxies: star clusters: individual: globular cluster
Abstract:
Researching the properties of the brightest globular cluster (referred
to as GC1) in M 81 can provide a fossil record of the earliest stages
of galaxy formation and evolution. The
Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolour Sky Survey
has carried out deep exposures of M 81.
We derive the magnitudes in intermediate-band filters of the BATC
system for GC1 and determine its age, mass, and structural parameters.
GC1 was observed by BATC using 14 intermediate-band filters covering a
wavelength range of 4000-10000Å. Based on photometric data in
BATC and Two Micron All Sky Survey near-infrared JHKs filters, we
constructed an extensive spectral energy distribution of GC1, spanning
the wavelength range from 4000 to 20000Å. By comparing multicolour
photometry with theoretical single stellar population synthesis
models, we derived the age and mass of GC1. In addition, we obtained
ellipticities, position angles, and surface brightness profiles for
GC1 based on the images of deep observations with the Advanced Camera
for Surveys on the Hubble Space Telescope. GC1 is better fitted by the
Wilson model than by the King and Sersic models in the F606W filter,
and it is better fitted by the Sersic model than by the King and
Wilson models in the F814W filter. The 'best-fit' half-light
radius of GC1 obtained here is 5.59pc, which is larger than the
majority of normal globular clusters (GCs) of the same luminosity.
The age and mass of GC1 estimated here are 13.0±2.90Gyr and
1.06-1.48x107M☉, respectively. The Rh versus MV diagram shows
that GC1 occupies the same area as extended star clusters. Therefore,
we suggest that GC1 is more likely an accreted former nuclear star
cluster than a classical GC similar to most of those in the Milky Way.
Description:
The HST images used here were observed in the ACS/WFC F606W and F814W
filters, which come from the HST programmes 10584 (PI: Andreas Zezas)
and 10250 (PI: John Huchra) (see for details from Santiago-Cortes et
al., 2010MNRAS.405.1293S 2010MNRAS.405.1293S, Cat. J/MNRAS/405/1293), respectively. We
obtained the combined drizzled images from the Hubble Legacy Archive.
File table4.dat is the intensity profiles for GC1 of M81,
corresponding to Table 4 in the paper.
Objects:
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RA (2000) DE Designation(s)
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09 55 21.97 +69 06 38.0 M81 GC1 = [NHM2010] 1029
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 60 157 Intensity profiles for GC1 of M81
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See also:
J/AJ/109/1055 : Globulars of M81 (Perelmuter+ 1995)
J/MNRAS/405/1293 : Compact star clusters in M81 (Santiago-Cortes+, 2010)
J/AJ/139/2620 : Spectroscopy of M81 globular clusters (Nantais+, 2010)
J/AJ/142/183 : HST photometry of globulars in M81 (Nantais+, 2011)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- ID [GC1] Name of the globular cluster
8- 14 A7 --- Detector [ACS/WFC] detector of HST
17- 21 A5 --- Filter [F606W F814W] filter of ACS/WFC of HST
24- 30 F7.4 arcsec R Clustercentric radius
34- 42 F9.3 Lsun/pc2 I Surface brightness in intensity
46- 53 F8.3 Lsun/pc2 e_I Uncertainty of intensity
58- 60 A3 --- Flag [OK DEP BAD] flag for every point
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Acknowledgements:
Shoucheng Wang, scwang(at)nao.cas.cn
(End) Patricia Vannier [CDS] 11-Mar-2021