J/AJ/107/1745 HST UVI photometry of M15. II. (Yanny+, 1994)
Globular cluster photometry with the Hubble Space Telescope. II.
U, V, and I measurements of M15
Yanny B., Guhathakurta P., Bahcall J.N., Schneider D.P.
<Astron. J. 107, 1745 (1994)>
=1994AJ....107.1745Y 1994AJ....107.1745Y
ADC_Keywords: Clusters, globular ; Photometry, UBV
Abstract:
The projected density distribution of resolved stars near the center
of M15 is shown to be consistent with either a power-law cusp
N(r) ∼ rα, with α ∼ -0.85±0.2, or with a King model
with a core of radius ≲ 2" (best fit r(core)=1.3"). The inferred
slope is in agreement with the theoretical value, α=-0.75,
calculated by Bahcall and Wolf for the distribution of equal-mass
stars surrounding a massive black hole and is also consistent with the
radial profile expected from core collapse without a central black
hole. The object AC 214 is a candidate for the central density cusp.
Analysis of Monte Carlo simulations of the diffuse light indicates
that, using current analysis techniques and available data, the
residual light is not a reliable indicator of the true density
distribution. This is contrary to earlier work. Photometric
measurements in V and I of more than 5x103 stars (and in U, V, and I
of ≳1500 stars) are used to construct color-magnitude diagrams in the
central 1' of M15. Fourteen blue straggler candidates are identified
in the inner 20". The central color gradient noticed by previous
researchers is caused by a central depletion of bright red giant stars
rather than an excess of blue stragglers or blue horizontal branch
stars.
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:
Yanny B.
Institute for Advanced Study, Princeton, New Jersey 08540
Guhathakurta P.
Princeton University Observatory, Peyton Hall, Princeton,
New Jersey 08544-1001
Bahcall J.N.
Schneider D.P.
Institute for Advanced Study, Princeton, New Jersey 08540
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 37 1186 Stellar photometry and astrometry for M15
(V < 18.1)
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See also:
J/AJ/106/154 : HST Observations in inner region of M15 (Ferraro+ 1993)
J/AJ/107/2067 : Fabry-Perot measurements of M15 (Gebhardt+, 1994)
J/AJ/110/704 : RR Lyrae in M15 (Silbermann+ 1995)
J/ApJ/347/251 : Dynamics of Globular Cluster M15 (Peterson+ 1989)
Byte-per-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Identification number (YGBS number)
6- 11 F6.2 arcsec oRA Right ascension offset from AC 211=ID 653 (1)
13- 18 F6.2 arcsec oDE Declination offset from AC 211=ID 653 (1)
20- 24 F5.2 mag Vmag Visual magnitude (filter F555W)
26- 30 F5.2 mag V-I V-I color (F785LP - F555W)
32- 36 F5.2 mag U-V ? U-V color (F336W - F555W)
37 A1 --- n_U-V [ab] Note for U-V (2)
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Note (1): Coordinates are arcsec offsets relative to AC 211 = ID 653.
ID 653 is at 21:29:58.26+12:10:02.90
Note (2): a - the star is located outside the area covered by the U image.
b - the star is not detected in U, though the area was covered.
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References:
Auriere M., Cordoni J.-P., =1981A&AS...46..347A 1981A&AS...46..347A
Origin: AAS CD-ROM series, Volume 2, 1994
(End) Lee Brotzman [ADS] 17-May-1994, Patricia Bauer [CDS] 24-Oct-1994