J/AJ/107/2067 Fabry-Perot measurements of M15 (Gebhardt+, 1994)
Fabry-Perot measurements of the dynamics of globular cluster cores:
M15 (NGC 7078)
Gebhardt K., Pryor C., Williams T.B., Hesser J.E.
<Astron. J. 107, 2067 (1994)>
=1994AJ....107.2067G 1994AJ....107.2067G (SIMBAD/NED Reference)
ADC_Keywords: Clusters, globular ; Radial velocities
Abstract:
We report the first use of the Rutgers Imaging Fabry-Perot
Spectrophotometer to study the dynamics of the cores of globular
clusters. We have obtained velocities for cluster stars by tuning the
Fabry-Perot to take a series of narrowband (0.8A FWHM at 5890A) images
at different wavelengths across one of the Na D (5890A) absorption
lines. Measuring the flux in every frame yields a short portion of the
spectrum for each star simultaneously. This proves to be a very
efficient method for obtaining accurate stellar velocities; in crowded
regions we are able to measure hundreds of velocities in 3-4h of
observing time. We have measured velocities with uncertainties of less
than 5km/s for 216 stars within 1.5' of the center of the globular
cluster M15 (NGC 7078). The velocity dispersion profile shows a sharp
rise from 7 to 12km/s at 0.6' (1.8parsec), and then appears to flatten
into our innermost point at 0.1'. A rotation amplitude of
1.4±0.8km/s is detected. The rotation has been measured at a radius
of 0.6' using stellar velocities and at 0.2' using the integrated
light profile. The amplitude and position angle are the same at both
radii, indicating a constant rotation profile in this region.
Combining our two epochs of Fabry-Perot observation with published
measurements, we have repeat velocity measurements for 67 stars. We
calculate a binary fraction of about 7% for binary periods between 0.2
and 20 years and mass ratios larger than 0.22, which is in agreement
with measurements for other globular clusters.
Objects:
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RA (2000) DE Designation(s)
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21 29 58.2 +12 10 02 M 15 = NGC 7078 = C 2127+119
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Addresses:
Gebhardt K. ,
Pryor C. ,
Williams T.B.
Department of Physics and Astronomy, Rutgers, The State University,
Box 0849, Piscataway, New Jersey 08855-0849
Hesser J.E.
Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics,
National Research Council of Canada, 5071 W. Saanich Road, R.R.5,
Victoria, B.C., V8X 4M6, Canada
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 61 480 M15 stars
table1.tex 93 507 LaTeX version of Table 1
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See also:
J/AJ/106/154 : HST Observations in inner region of M15 (Ferraro+ 1993)
J/AJ/107/1745 : HST UVI photometry of M15. II. (Yanny+, 1994)
J/AJ/110/704 : RR Lyrae in M15 (Silbermann+ 1995)
J/ApJ/347/251 : Dynamics of Globular Cluster M15 (Peterson+ 1989)
Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 6 A6 --- ID Star ID, blank indicates continuations (1)
8- 13 F6.1 arcsec Xoff X offset from cluster center (2)
16- 21 F6.1 arcsec Yoff Y offset from cluster center (2)
24- 27 F4.1 mag FPVmag Fabry-Perot V magnitude
30- 35 F6.1 km/s RVel Velocity (3)
38- 40 F3.1 km/s e_RVel Error in velocity
43- 46 A4 --- r_RVel Source for velocity (4)
49- 52 F4.2 --- ChiSq []? Chi-square for multiple measurements (5)
53- 62 A10 --- Note Notes (6)
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Note (1): ID is taken from
Kuestner, F. 1921, Veroeff. Sternw. Bonn., No. 15 =1921VeUSB..15....1K 1921VeUSB..15....1K
or Auriere, M., & Cordoni, J.P. 1981, =1981A&AS...46..347A 1981A&AS...46..347A
if the star has been previously studied, or an FP number if it has not.
Note (2): The center of the cluster was taken to be
21h27m33.3s, +11d56m49s (1950), as measured by HST
(Lauer, T.R. et al. =1991ApJ...369L..45L 1991ApJ...369L..45L)
Note (3): When there are multiple velocity measurements for the same star,
the first line for that star lists the average velocity calculated
from all of the measurements weighted by their uncertainties and the
following lines are the individual measurements.
Note (4): Source of velocity measurement. All the measurements from
Peterson R.C., Seitzer P. & Cudworth K.M. (1989ApJ...347..251P 1989ApJ...347..251P)
(PSC) are included. Other sources are listed as FP91 or FP92 for the
authors 1991 or 1992 Fabry-Perot observations.
Note (5): Probability of chi-square for multiple measurements being drawn
from the same velocity.
Note (6): Notes include code numbers, as follows:
1: Binary star candidates
2: Not used in dynamics due to radical FP bias
3: Not used in dynamics due to severe contamination
4: PSC has 33 measurements for this star
Other notes include additional ID's for stars, as follows:
V: Variable star number (Sawyer-Hogg, H. 1973, Publ. David
Dunlap Obs., 3, No. 6)
S: Sandage, A. (1970ApJ...162..841S 1970ApJ...162..841S)
I-V: Roman numerals from Arp, H.C. (1955AJ.....60..317A 1955AJ.....60..317A)
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Origin: AAS CD-ROM series, Volume 3, 1995
(End) Lee Brotzman [ADS] 16-Aug-1994, Patricia Bauer [CDS] 15-Feb-1995