J/ApJ/677/1069 Blue stragglers in NGC 6388 (Dalessandro+, 2008)
Blue straggler stars in the unusual globular cluster NGC 6388.
Dalessandro E., Lanzoni B., Ferraro F.R., Rood R.T., Milone A., Piotto G.,
Valenti E.
<Astrophys. J., 677, 1069-1079 (2008)>
=2008ApJ...677.1069D 2008ApJ...677.1069D
ADC_Keywords: Clusters, globular ; Photometry, UBV ; Stars, blue
Keywords: binaries: general - blue stragglers - stars: horizontal-branch -
globular clusters: individual (NGC 6388) - stars: evolution
Abstract:
We have used multiband high-resolution HST WFPC2 and ACS observations
combined with wide-field ground-based observations to study the blue
straggler star (BSS) population in the Galactic globular cluster NGC 6388.
As in several other clusters we have studied, the BSS distribution is
found to be bimodal: highly peaked in the cluster center, rapidly
decreasing at intermediate radii, and rising again at larger radii. In
other clusters the sparsely populated intermediate-radius region (or
"zone of avoidance") corresponds well to that part of the cluster
where dynamical friction would have caused the more massive BSSs or
their binary progenitors to settle to the cluster center. Instead, in
NGC 6388, BSSs still populate a region that should have been cleaned
out by dynamical friction effects, thus suggesting that dynamical
friction is somehow less efficient than expected. As a by-product of
these observations, the peculiar morphology of the horizontal branch
(HB) is also confirmed. In particular, within the (very extended) blue
portion of the HB we are able to clearly characterize three
subpopulations: ordinary blue HB stars, extreme HB stars, and blue
hook stars. Each of these populations has a radial distribution which
is indistinguishable from normal cluster stars.
Description:
We have used a combination of high-resolution and wide-field
photometric data sets. The high-resolution set consists of a series of
public multiband (from UV to optical) Wide Field Planetary Camera 2
(WFPC2) and Advanced Camera for Surveys (ACS) HST images, which have
been retrieved from the ESO/ST-ECF Science Archive. The wide-field set
is a complementary set of public B and V images obtained with the Wide
Field Imager (WFI) mounted at the 2.2m ESO-MPI telescope at La Silla
Observatory and retrieved from the ESO Science Archive.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 55 153 The blue straggler star population of NGC 6388
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See also:
J/A+A/314/448 : UBV photometry of a blue straggler in NGC 2354 (Lapasset+,
1996)
J/A+A/324/915 : Blue stragglers in M3 (Ferraro+ 1997)
J/ApJ/648/1026 : HST photometry of M5 blue stragglers (Warren+, 2006)
J/ApJ/663/267 : Blue straggler population of globular cluster M5 (Lanzoni+,
2007)
J/A+A/483/183 : Catalogue of Blue Stragglers (Moretti+, 2008)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [BSS-]
5- 7 I3 --- BSS [1/153] Blue straggler star number
(<Cl* NGC 6388 BSS NNN> in Simbad)
9- 19 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000)
21- 31 F11.7 deg DEdeg Declination in decimal degrees (J2000)
33- 37 F5.2 mag F255W ? WFPC2 F255W filter magnitude
39- 43 F5.2 mag Umag ? U band magnitude
45- 49 F5.2 mag Bmag ? B band magnitude
51- 55 F5.2 mag Vmag ? V band magnitude
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Sep-2010