J/ApJ/625/156 FUV-NUV observations of NGC 2808 (Dieball+, 2005)
Far-ultraviolet observations of the globular cluster NGC 2808 revisited:
blue stragglers, white dwarfs, and cataclysmic variables.
Dieball A., Knigge C., Zurek D.R., Shara M.M., Long K.S.
<Astrophys. J., 625, 156-166 (2005)>
=2005ApJ...625..156D 2005ApJ...625..156D
ADC_Keywords: Clusters, globular ; Stars, blue ; Stars, white dwarf ;
Stars, variable ; Photometry, HST ; Ultraviolet
Keywords: blue stragglers - globular clusters: individual (NGC 2808) -
novae, cataclysmic variables - white dwarfs
Abstract:
We present a reanalysis of far-ultraviolet (FUV) observations of the
globular cluster NGC 2808 obtained with the Hubble Space Telescope.
These data were first analyzed by Brown and coworkers (2001, Cat.
J/ApJ/562/368), with an emphasis on the bright, blue
horizontal-branch (HB) stars in this cluster. Here, our focus is on
the population of fainter FUV sources, which include white dwarfs
(WDs), blue stragglers (BSs), and cataclysmic variables (CVs).
Description:
NGC 2808 was observed with the Space Telescope Imaging Spectrograph
(STIS) on board the HST in 2000 January-February.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 521 Catalog of all FUV-NUV sources
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See also:
J/ApJ/562/368 : UV photometry in NGC 2808 (Brown+, 2001)
J/A+A/391/945 : HST photometry of 74 galactic globular clusters (Piotto+ 2002)
J/A+AS/84/59 : Photometry of NGC 2808 (Ferraro+, 1990)
J/A+A/417/597 : Radial velocities in 4 globular clusters (Recio-Blanco+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running identification number
5 I1 h RAh Hour of Right Ascension (J2000.0) (1)
7- 8 I2 min RAm Minute of Right Ascension (J2000.0) (1)
10- 14 F5.3 s RAs Second of Right Ascension (J2000.0) (1)
16 A1 --- DE- Sign of the Declination (J2000.0) (1)
17- 18 I2 deg DEd Degree of Declination (J2000.0) (1)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000.0) (1)
23- 28 F6.3 arcsec DEs Arcsecond of Declination (J2000.0) (1)
30- 35 F6.3 mag FUVmag F25QTZ (1590Å) far-UV band magnitude
37- 41 F5.3 mag e_FUVmag Error on FUVmag
43- 48 F6.3 mag NUVmag ? F25CN270 (2700Å) near-UV band magnitude
50- 54 F5.3 mag e_NUVmag ? Error on NUVmag
56- 61 F6.3 mag DFUV ? Difference between Brown et al. (2001, Cat.
J/ApJ/562/368) and this paper's FUV
photometry
63- 68 F6.3 mag DNUV ? Difference between Brown et al. (2001, Cat.
J/ApJ/562/368) and this paper's NUV
photometry
70- 74 F5.2 arcsec Rad Distance to the cluster center (2)
76- 78 I3 --- Brown ? Identification number from Brown et al.
(2001, Cat. J/ApJ/562/368)
80- 84 I5 --- Piotto ? Identification number from Piotto et al.
(2002, Cat. J/A+A/391/945),
Cl* NGC 2808 Piotto NNNNN in Simbad
86- 91 F6.3 mag Vmag ? The V band magnitude
93- 98 F6.3 mag Bmag ? The B band magnitude
100-109 A10 --- Com Additional comments (3)
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Note (1): Our α δ coordinates are based on the (J2000.0)
coordinate system given by the FITS-headers, but have been
shifted to achieve the best match to the Brown et al. (2001, Cat.
J/ApJ/562/368) coordinates. This required offsets of -0.13" in
α and -0.6" in δ, after which the rms differences between
our coordinates and Brown et al.'s are only 0.006" in α and
0.048" in δ. However, as noted in Brown et al. although the
relative astrometry is very accurate, the error in the absolute
astrometry is much larger (∼1-2").
Note (2): Using star number counts, we determined the cluster center at
α=9:12:2.96 and δ=-64:51:47.78 (J2000.0).
Note (3): Additional comments, defined as follows:
a = The tolerance radius for matching these sources in FUV and NUV was
increased from 1.5 to 2 pixels.
n = These pairs were added by hand, see text for details.
e = These stars show a somewhat elongated shape on the FUV mosaic and are
located mainly in its outer regions.
v = Good variable candidate, see text for details.
pv = Possible variable candidate, but too few measurements for a reliable
statement.
nv = Unsure variable candidate, measurements on the single images agree
within the errors.
pv-f = Unsure variable candidate: faint companion to a bright star.
Measurements on the single images are extremely difficult and thus not
very reliable.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 23-Nov-2005