J/AJ/143/121 UV properties of Galactic globulars with GALEX. (Schiavon+, 2012)
Ultraviolet properties of Galactic globular clusters with GALEX.
I. The color-magnitude diagrams.
Schiavon R.P., Dalessandro E., Sohn S.T., Rood R.T., O'Connell R.W.,
Ferraro F.R., Lanzoni B., Beccari G., Rey S.-C., Rhee J., Rich R.M.,
Yoon S.-J., Lee Y.-W.
<Astron. J., 143, 121 (2012)>
=2012AJ....143..121S 2012AJ....143..121S
ADC_Keywords: Clusters, globular ; Photometry, ultraviolet ; Stars, giant
Keywords: globular clusters: general - Hertzsprung-Russell and C-M diagrams -
stars: evolution
Abstract:
We present Galaxy Evolution Explorer (GALEX) data for 44 Galactic
globular clusters (GCs) obtained during three GALEX observing cycles
between 2004 and 2008. This is the largest homogeneous data set on the
UV photometric properties of Galactic GCs ever collected. The sample
selection and photometric analysis are discussed, and color-magnitude
diagrams (CMDs) are presented. The blue and intermediate-blue
horizontal branch is the dominant feature of the UV CMDs of old
Galactic GCs. Our sample is large enough to display the remarkable
variety of horizontal branch shapes found in old stellar populations.
Other stellar types that are obviously detected are blue stragglers
and post-core-He burning stars. The main features of UV CMDs of
Galactic GCs are briefly discussed. We establish the locus of
post-core-He burning stars in the UV CMD and present a catalog of
candidate asymptotic giant branch (AGB), AGB-manque, post early-AGB,
and post-AGB stars within our cluster sample.
Description:
GALEX is a 50cm orbiting UV telescope launched in 2003 April, with a
spatial resolution of ∼4.5" and 5.5" in FUV and NUV bands,
respectively. The data presented in this paper were primarily
collected under GALEX GI programs 056 and 099 (PI: R. Schiavon) in
Cycles 1 and 4, respectively. Finally, we further include data for six
out of eight Galactic GCs from Cycle 3 GI program 075 (PI: S. T. Sohn).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 56 44 List of globular clusters studied
table3.dat 61 124 Post-He-core burning candidates
--------------------------------------------------------------------------------
See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
VI/65 : Evolutionary models of evolved stars (Dorman+ 1993)
J/ApJS/199/37 : GALEX catalog of star clusters in M31 (Kang+, 2012)
J/ApJS/182/509 : Blue stragglers in M2 (Dalessandro+, 2009)
J/ApJ/681/311 : Blue stragglers in NGC 2419 (Dalessandro+, 2008)
J/ApJS/171/146 : Population synthesis in the blue. IV (Schiavon+, 2007)
J/ApJS/173/643 : GALEX UV photometry of M31 Globular Clusters (Rey+, 2007)
J/A+A/469/529 : UBVI photometry of NGC 6864 (Kravtsov+, 2007)
J/AJ/131/866 : Hot populations in M87 globular clusters (Sohn+, 2006)
J/ApJ/625/156 : FUV-NUV observations of NGC 2808 (Dieball+, 2005)
J/ApJ/562/368 : UV photometry in NGC 2808 (Brown+, 2001)
J/A+AS/141/371 : Low-mass stars evolutionary tracks + isochrones (Girardi+,
2000)
J/A+A/324/915 : Blue stragglers in M3 (Ferraro+ 1997)
J/AJ/112/601 : UV photometry in M79 (Hill+ 1996)
J/AJ/108/1350 : Omega Cen FUV photometry (Whitney+, 1994)
J/A+A/287/769 : UV photometry of NGC 6397 (Burgarella+ 1994)
J/AJ/97/1360 : BV photometry of Palomar 12 (Stetson+ 1989)
http://www.cosmic-lab.eu/uvggc/archive.php : GALEX UV photometric database
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Cluster Target name
10- 14 I5 s ExpF Exposure time in FUV
16- 20 I5 s ExpN ? Exposure time in NUV
22- 28 F7.3 deg RAdeg Cluster right ascension in decimal
degrees (J2000)
30- 36 F7.3 deg DEdeg Cluster declination in decimal
degrees (J2000)
38- 48 A11 "YYYY/MMM/DD" Obs Observation date (from 2004/Dec/06 to
2008/May/31)
50- 56 A7 --- Cycle Cycle (GI1, GI1/MIS, GI3, or GI4)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Cluster Cluster name
10- 13 I4 --- Star [1/5695] Star number
15- 20 F6.3 mag FUVmag [10.895/20.167] FUV magnitude (1350-1780Å)
22- 27 F6.3 mag NUVmag [12.355/20.409] NUV magnitude (1770-2730Å)
29- 30 I2 h RAh Hour of right ascension (J2000)
32- 33 I2 min RAm Minute of right ascension (J2000)
35- 40 F6.3 s RAs Second of right ascension (J2000)
42 A1 --- DE- Sign of declination (J2000)
43- 44 I2 deg DEd Degree of declination (J2000)
46- 47 I2 arcmin DEm Arcminute of declination (J2000)
49- 53 F5.2 arcsec DEs Arcsecond of declination (J2000)
55- 61 A7 --- Class Class: P(E)AGB = post-(early)AGB star,
PAGB = post-AGBstar, AGBM = AGB-manque (1)
--------------------------------------------------------------------------------
Note (1): According to standard stellar evolution theory, post-HB evolution
depends strongly on the mass of the stellar envelope. After core-He
exhaustion, stars with the highest envelope masses evolve into the
AGB phase, undergoing thermal pulses and eventually losing their
envelopes, evolving toward higher temperatures at constant high
luminosity as PAGB stars. Stars with lower envelope mass experience a
much shier excursion into the AGB phase and never undergo thermal
pulses, evolving toward higher temperatures, after envelope loss, at
constant, but lower, luminosities. The latter are called post
early-AGB (PEAGB) stars. Finally, at the extreme low end of envelope
mass, stars never make it to AGB phase after core-He exhaustion,
departing the blue end of the HB in a small excursion toward higher
luminosities, but never becoming as bright as PEAGB stars. The latter
are the so-called AGB-manque (AGBM) stars. See section 4.
--------------------------------------------------------------------------------
Nomenclature Notes:
In table 3, stars are <[SDS2012] {Cluster} NNNNN> in Simbad.
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 31-Aug-2012