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J/ApJ/670/379       UV photometry of M15                    (Dieball+, 2007)

Unveiling the core of the globular cluster M15 in the ultraviolet. Dieball A., Knigge C., Zurek D.R., Shara M.M., Long K.S., Charles P.A., Hannikainen D. <Astrophys. J., 670, 379-399 (2007)> =2007ApJ...670..379D
ADC_Keywords: Clusters, globular ; Ultraviolet ; Photometry, UBVRI Keywords: binaries: close - globular clusters: individual (M15) - ultraviolet: stars Abstract: We have obtained deep FUV and NUV images of the inner region of the dense globular cluster M15 with the HST ACS. The FUV-NUV color-magnitude diagram shows a well-defined track of horizontal branch stars, as well as a trail of blue stragglers and white dwarfs. The main-sequence turnoff is clearly visible at FUV∼22.5mag and FUV-NUV∼3mag, and the main-sequence stars form a prominent track that extends at least 2mag below the main-sequence turnoff. As such, this is the deepest FUV-NUV color-magnitude diagram of a globular cluster presented so far. Cataclysmic variable and blue straggler candidates are the most centrally concentrated stellar populations, which might either be an effect of mass segregation or reflect the preferred birthplace in the dense cluster core of such dynamically formed objects. We find 41 FUV sources that exhibit significant variability. We classify the variables based on an analysis of their UV colors and variability properties. We find four previously known RR Lyrae and 13 further RR Lyrae candidates, one known Cepheid and six further candidates, six cataclysmic variable candidates, one known and one probable SX Phoenicis star, and the well-known low-mass X-ray binary AC 211. Our analysis represents the first detection of SX Phoenicis pulsations in the FUV. We find that Cepheids, RR Lyrae stars, and SX Phoenicis exhibit massive variability amplitudes in this wave band (several magnitudes). Description: M15 was observed with the ACS onboard HST for a total of 10 orbits in 2003 October and 2004 October to December. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 118 2729 Catalog of all sources in our FUV field of view
See also: J/AJ/124/3255 : UBV photometry in M15 (van der Marel+, 2002) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [DKZ2007] Running identification number 6- 7 I2 h RAh Hour of Right Ascension (J2000) 9- 10 I2 min RAm Minute of Right Ascension (J2000) 12- 17 F6.3 s RAs Second of Right Ascension (J2000) 18 A1 --- DE- Sign of Declination (J2000) 19- 20 I2 deg DEd Degree of Declination (J2000) 22- 23 I2 arcmin DEm Arcminute of Declination (J2000) 25- 30 F6.3 arcsec DEs Arcsecond of Declination (J2000) 32- 39 F8.3 pix Xpix The X pixel coordinate 41- 48 F8.3 pix Ypix The Y pixel coordinate 50- 55 F6.3 mag FUVmag ACS far-UV magnitude in F140LP filter 57- 61 F5.3 mag e_FUVmag Error in FUVmag 63- 68 F6.3 mag FUV-NUV ? ACS (FUV-NUV) color (F140LP-F220W) (1) 70- 74 F5.3 mag e_FUV-NUV ? Error in FUV-NUV (1) 76- 80 F5.3 pix Tol ? Matching radius between NUV and transformed FUV cartesian coordinates (1) 82- 87 F6.3 arcsec Rad Radius from the cluster center (2) 89- 94 F6.3 mag Vmag ? V magnitude from Van der Marel et al. (2002, Cat. J/AJ/124/3255) (1) 96-101 F6.3 mag Bmag ? B magnitude from Van der Marel et al. (2002, Cat. J/AJ/124/3255) (1) 103-108 F6.3 mag Umag ? U magnitude from Van der Marel et al. (2002, Cat. J/AJ/124/3255) (1) 110-114 I5 --- VdM ? Identification form Van der Marel et al. (2002, Cat. J/AJ/124/3255) (1) 116-118 A3 --- Var Variable source identification, VNN
Note (1): A blank value indicates either there is no match with a NUV source and/or with an optical source. Note (2): At Xpix∼900 and Ypix∼850 in our FUV master image, determined from star number counts in both master images.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 30-Jan-2010
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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