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J/AJ/124/1486       M4 UBV color-magnitude diagrams          (Mochejska+, 2002)

Clusters ages experiment: hot subdwarfs and luminous white dwarf candidates in the field of the globular cluster M4. Mochejska B.J., Kaluzny J., Thompson I., Pych W. <Astron. J. 124, 1486 (2002)> =2002AJ....124.1486M
ADC_Keywords: Clusters, globular ; Photometry, UBV ; Stars, white dwarf Keywords: globular clusters: individual (M4) - Hertzsprung-Russell diagram - subdwarfs - white dwarfs Abstract: We present UBV color-magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V←0.6), which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the presence of a population of faint blue objects, likely to be hot, young white dwarfs belonging to the cluster. We have selected five objects above V=22mag, bright enough for follow-up ground-based spectroscopy, and present their coordinates and finding charts. We show a spectrum for variable V46, which suggests that it is a hot subdwarf, along with a new light curve obtained with the ISIS image subtraction package. The light curve is unstable, but only one period of variability is apparent. Two new variables have been discovered, both located on the cluster red giant branch. We also present a differential E(B-V) reddening map and a fiducial sequence for the main sequence, subgiant branch, and red giant branch on the V/B-V CMD for a selected region with uniform reddening. Based on a comparison with the M5 fiducial sequence, we obtain a reddening estimate of E(B-V)=0.41mag toward M4, consistent with previous determinations. Description: The photometric data were obtained with the 2.5m du Pont telescope at Las Campanas Observatory. An 8.8x8.8 field centered on the cluster was monitored during five consecutive nights, from 1995 June 1 to 5. Observations were made through Johnson UBV filters. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file m4wd.dat 87 37 UBV photometry and astrometry of the white dwarfs m4ubv.dat 114 12121 Astrometry and UBV photometry for 12121 stars in M4
See also: J/PAZh/22/847 : Identification and coordinates in M4 (Shokin+, 1996) J/AJ/114/189 : M 4 CCD photometry (Alcaino+, 1997) J/ApJS/120/265 : HST photometry of M4 (Ibata+, 1999) J/AJ/127/2771 : HST proper-motions of M4 main-sequence stars (Richer+, 2004) Byte-by-byte Description of file: m4wd.dat
Bytes Format Units Label Explanations
1- 2 A2 --- --- [WD] 3- 4 I2 --- MKTWD Sequential WD number, Cl* NGC 6121 MKTWD NN in Simbad 6- 15 F10.6 deg RAdeg Right ascension (J2000) 18- 27 F10.6 deg DEdeg Declination (J2000) 29- 34 F6.3 mag Vmag Johnson V magnitude 37- 41 F5.3 mag e_Vmag rms uncertainty on Vmag 43- 48 F6.3 mag B-V ?=-9.999 Johnson B-V colour index 50- 55 F6.3 mag e_B-V ?=-9.999 rms uncertainty on B-V 57- 62 F6.3 mag U-B ?=-9.999 Johnson U-B colour index 64- 69 F6.3 mag e_U-B ?=-9.999 rms uncertainty on U-B 71- 76 F6.3 mag U-V ?=-9.999 Johnson U-V colour index 78- 83 F6.3 mag e_U-V ?=-9.999 rms uncertainty on U-V 87 A1 --- Class [A-C] Class of the object (1)
Note (1): Class as follows: A = very good candidates B = good candidates C = poorer candidates
Byte-by-byte Description of file: m4ubv.dat
Bytes Format Units Label Explanations
1- 5 I5 --- MKT Sequential number, Cl* NGC 6121 MKT NNNNN in Simbad 7- 13 F7.2 pix Xpos X position 15- 21 F7.2 pix Ypos Y position 23- 32 F10.6 deg RAdeg Right ascension (J2000) 34- 43 F10.6 deg DEdeg Declination (J2000) 45- 50 F6.3 mag Vmag Johnson V magnitude 53- 57 F5.3 mag e_Vmag rms uncertainty on Vmag 59- 64 F6.3 mag B-V ?=-9.999 Johnson B-V colour index 66- 71 F6.3 mag e_B-V ?=-9.999 rms uncertainty on B-V 73- 78 F6.3 mag U-B ?=-9.999 Johnson U-B colour index 80- 85 F6.3 mag e_U-B ?=-9.999 rms uncertainty on U-B 87- 92 F6.3 mag U-V ?=-9.999 Johnson U-V colour index 94- 99 F6.3 mag e_U-V ?=-9.999 rms uncertainty on U-V 101-114 A14 --- Note Hot subdwarf candidate (BN) or Variable (VNN) identification
History: From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 08-Nov-2002
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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