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J/AJ/109/1055                 Globulars of M81                (Perelmuter+ 1995)

The Globular Cluster System of M81 Perelmuter J.M., Racine M. <Astron. J. 109, 1055 (1995)> =1995AJ....109.1055P
ADC_Keywords: Galaxies, optical; Clusters, globular; Photometry; Astrometric data; Morphology Abstract: We have obtained photometric BVR, morphological, and astrometric information on 3774 objects located within a 25' radius of M81. This catalogue is complete for 15 ≤ V ≤ 21; it is used here to identify globular cluster candidates in M81 and as a database for a statistical analysis of the system as a whole. The M81 globular cluster system is revealed as a strong surface density excess of ∼70 objects within an 11 kpc galactocentric radius. The total population is estimated at N_T = 210 ± 30 globulars. The spatial, (B-V), and (V-R) distributions are very similar to those of the Milky Way and of M31. Small but significant systematic errors in Madore et al.'s [AJ, 106, 2243 (1993)] photometry could be responsible for an overestimate of the Cepheid distance to M81 [(m-M)0 = 27.8] and we propose a revised modulus of (m-M)0 = 27.5 ± 0.3. The globular cluster luminosity function then reaches its maximum at M_V* = -7.5 ± 0.4, as it does in the galaxy and in M31. There is suggestive evidence that 13 ± 5 objects are globulars seen through the disk of M81; spectroscopy or high-resolution imaging will resolve this issue. Using the (B-R)0 index to trace [Fe/H], we notice a weak dependence of mean metallicity on galactocentric distance, as observed in the galaxy and in M31. This result argues in favour of in situ globular formation during the continuous collapse and self-enrichment of an early-type spiral host. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table6.dat 74 3774 Catalogue of objects in the M81 field
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 5 I5 --- ID Identification number [PR95] 8- 9 I2 h RAh Right ascension (J2000) 11- 12 I2 min RAm R.A. 14- 19 F6.3 s RAs R.A. 20 A1 --- DE- Declination (always blank) 21- 22 I2 deg DEd Declination (J2000) 24- 25 I2 arcmin DEm Dec. 27- 31 F5.2 arcsec DEs Dec. 33- 38 F6.1 yr Epoch Mean epoch of observation 40- 44 F5.2 mag Vmag V magnitude 46- 50 F5.2 mag B-V B-V color 52- 56 F5.2 mag V-R V-R color 57- 58 I2 --- N Number of plates object detected upon 60- 63 I4 mas/yr pmGlon Proper motion in galactic longitude 65- 68 I4 mas/yr pmGlat Proper motion in galactic latitude 70- 74 F5.1 --- pmSig *Level of significance of total PM
Note on pmSig: The level of significance of the total proper motion, mu/sig_mu, where mu is the total proper motion = (pmGlon^2 + pmGlat2)(1/2)
Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 03-May-1995
(End) [CDS] 11-Jul-1995
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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