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J/AJ/113/1026           Fabry-Perot Observations of M15         (Gebhardt+ 1997)

Fabry-Perot Observations of Globular Clusters. III. M15 Gebhardt K., Pryor C., Williams T.B., Hesser J.E., Stetson P.B. <Astron. J. 113, 1026 (1997)> =1997AJ....113.1026G
ADC_Keywords: Clusters, globular ; Radial velocities Abstract: We have used an Imaging Fabry-Perot Spectrophotometer with the Sub-arcsecond Imaging Spectrograph on the Canada-France-Hawaii Telescope to measure velocities for 1534 stars in the globular cluster M15 (NGC 7078) with uncertainties between 0.5 and 10km/s. Combined with previous velocity samples, the total number of stars with measured velocities in M15 is 1597. An average seeing of 0.8" allowed us to obtain velocities for 144 stars within 10" of the center of M15, including 12 stars within 2". The velocity dispersion profile for M15 remains flat at a value of 11km/s from a radius of 0.4 into our innermost reliable point at 0.02 (0.06pc). Assuming an isotropic velocity dispersion tensor, this profile and the previously-published surface brightness profile can be equally well represented either by a stellar population whose M/L varies with radius from 1.7 in solar units at large radii to 3 in the central region, or by a population with a constant M/L of 1.7 and a central black hole of 1000M. A non-parametric mass model that assumes no black hole, no rotation, and isotropy constrains the mass density of M15 to better than 30% at a radius of 0.07 parsecs. The mass-density profile of this model is well represented by a power law with an exponent of -2.2, the value predicted by models of cluster core-collapse. Using the assumption of local thermodynamic equilibrium, we estimate the present-day mass function and infer a significant number of 0.6-0.7 M objects in the central few parsecs, 85% of which may be in the form of stellar remnants. Not only do we detect rotation; we find that the position angle of the projected rotation axis in the central 10" is 100deg different from that of the whole sample. We also detect an increase in the amplitude of the rotation at small radii. Although this increase needs to be confirmed with better-seeing data, it may be the result of a central mass concentration. (Copyright) 1997 American Astronomical Society. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 21 29 58.3 +12 10 00 M 15 = NGC 7078 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 53 1601 Velocity data table1.tex 70 1621 AASTeX version of table1.dat table2.dat 70 512 Repeat measurements table2.tex 108 537 AASTeX version of table2.dat
See also: J/AJ/110/1699 : Paper II. (47 Tuc, NGC 6397 & M30) (Gebhardt+ 1995) J/ApJ/347/251 : Dynamics of Globular Cluster M15 (Peterson+ 1989) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 A5 --- ID Star identification 7- 13 F7.1 arcsec Xpos *X offset from cluster center (eastward) 15- 21 F7.1 arcsec Ypos *Y offset from cluster center (northward) 23- 29 F7.1 km/s Vel Mean velocity 31- 35 F5.1 km/s e_Vel Uncertainty in Vel 37- 41 F5.1 mag V(FP) *Fabry-Perot magnitude 44- 48 F5.3 % Prob *? Probability of the chi-square 50- 53 A4 --- Note *Note
Note on Xpos, Ypos: The cluster center coordinates are given in Guhathakutra et al. 1996AJ....111..267G Note on V(FP): Fabry-Perot magnitude, estimated from the fitted continuum of the authors' 3 Angstrom spectrum. Note on Prob: The probability of the chi-square from the multiple measurements exceeding the observed value -- a low probability suggests a variable velocity -- or a note. Note on Note: A note of 'bias' indicates the star is beyond the unbiased radius and is not used in the dynamical analysis. A note of 'non' indicates the star was determined to be a non-member based on its radial velocity.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 A5 --- ID Star identification 7- 13 F7.1 km/s CFHT95 ? Velocity from the 1995 CFHT data 15- 18 F4.1 km/s e_CFHT95 ? Uncertainty in CFHT95 20- 26 F7.1 km/s CFHT94 ? Velocity from the 1994 CFHT data 28- 31 F4.1 km/s e_CFHT94 ? Uncertainty in CFHT94 33- 39 F7.1 km/s FP92 ? Velocity from 1992 CTIO data (paper I, Pryor et al., 1993BAAS...25Q1406P) 41- 44 F4.1 km/s e_FP92 ? Uncertainty in FP92 46- 52 F7.1 km/s FP91 ? Velocity from 1991 CTIO data (paper I, Pryor et al., 1993BAAS...25Q1406P) 54- 57 F4.1 km/s e_FP91 ? Uncertainty in FP91 59- 65 F7.1 km/s PSC ? Velocity from Peterson et al. (1989) (Cat. J/ApJ/347/251) 67- 70 F4.1 km/s e_PSC ? Uncertainty in PSC
Origin: AAS CD-ROM series, Volume 8, 1997 Lee Brotzman [ADS] 09-Apr-1997 References: Pryor et al., Paper I. 1993BAAS...25Q1406P
(End) [CDS] 04-Jul-1997
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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