CDROM/AJ/V112/P0601 UIT: M79 (Hill+ 1996) ================================================================================ UIT: New Ultraviolet Stellar Photometry and Surface Brightness Profiles of the Globular Cluster M79 (NGC 1904) Robert S. Hill, K.-P. Cheng, Eric P. Smith, Paul M. N. Hintzen, Ralph C. Bohlin, Robert W. O'Connell, Morton S. Roberts, Andrew M. Smith, and Theodore P. Stecher <1996, AJ, 112, 601> =1996AJ....112..601H ================================================================================ Abstract: Ultraviolet photometry is presented for the globular cluster M79 (NGC 1904) according to the final calibration of the images obtained on the Astro-1 Spacelab mission by the Ultraviolet Imaging Telescope. These results include both point-source and surface photometry at 152 nm and 249 nm. An ultraviolet color-magnitude (C-M) diagram in these bandpasses is presented. The detected stars are also cross-matched with the ground-based photometry of Ferraro et al. to produce C-M and two-color diagrams covering a 4000 A span in wavelength. The observed horizontal branch (HB) is compared with stellar interior models of the zero-age HB (ZAHB). Many stars are found in post-HB evolutionary stages more luminous than the ZAHB. The distribution of stars along the ZAHB in m152-m249 color is investigated, and an indication of possible bimodality is found. The relative population of the blue HB tail may vary with radius for radii greater than 1'. Ultraviolet surface brightness and color-index profiles are presented. The previously reported central gradient in the m152-V color index is confirmed, and a faint diffuse component is detected outside a radius of 40" in the 152 nm band. Two possible causes of the central color gradient are discussed: mass segregation, and the destruction of red giant envelopes by enhanced mass loss in the cluster core. File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table3.dat 75 136 UV stellar photometry of M79 table3.fit 2880 10 FITS ASCII table version of table3.dat -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Star Ordinal number of UIT-detected star in M79 4 1X --- --- Blank 5 A1 --- Note *[g] Table note mark 6- 8 I3 min RAm Right ascension (2000) 05 hours implicit 9-14 F6.2 s RAs R.A. 15-17 I3 arcmin DEm *Declination (2000) -24 degrees implicit 18-22 F5.1 arcsec DEs Dec. 23-24 2X --- --- Blank 25-29 F5.2 mag m152 *UIT magnitude in the 152 nm (B1) band 30-35 F6.2 mag C152-179 UIT color index 152 nm (B1) - 249 nm (A1) 36-41 F6.3 mag e_m152 Formal error in UIT 152 nm (B1) magnitude 42-47 F6.3 mag e_m249 Formal error in UIT 249 nm (A1) magnitude 48-53 F6.1 arcsec R Distance of UIT source from cluster center 54 1X --- --- Blank 55-59 A5 --- Q_note *Note on quality of observation 60-63 I4 --- F92_ID *Star number from reference F92 64-69 F6.2 mag F92_BV []? B-V color index from F92 70-75 F6.2 mag F92_V []? V magnitude from F92 -------------------------------------------------------------------------------- Notes for file: table1.dat -------------------------------------------------------------------------------- Note: Table note mark "g": Star 94=UIT-1 and star 76 = UIT-2 as discussed in Paper I (Hill, R. S. et al. 1992, ApJ, 295, L17). Stars 26, 67, 100, 109, and 127 are in the area observed by F92 but have no F92-HB match with B-V < 0.4. Stars 111, 120, and 122 are ambiguously matched by two or more F92 HB stars. DEm: Note that these minutes are minus, and should be simply concatenated with the -24 degrees and the seconds to obtain the usual notation. E.g., if DEm = 45 and DEs = 36.2, then the declination is -24d 45m 36.2s. m152: UIT magnitude in the 152 nm (B1) band. Magnitudes are defined as -2.5*log(flux)-21.1, where log is base 10, and flux is f sub lambda in units of ergs/cm2/s/A. Q_note: Note on quality of observation. *: UIT source is within 5 pixels (5.7 arcsec) of more than one HB star of F92; if an F92 number is given, it is judged the most likely candidate according to color index and distance from the UIT source position. C: Obvious crowding in one or both UIT bands, as determined by inspection; stars without this note may still be affected by crowding if r < about 40 arcsec. Lowercase f or n: An aperture magnitude is substituted for a PSF magnitude with error greater than 0.2 mag, for image FUV0141 or NUV0124, respectively. Entries 134-136 have aperture photometry only. F92_ID: The reference F92 is the following: Ferraro, F. R., Clementini, G., Fusi Pecci, F., Sortino, R., and Buonanno, R. 1992, MNRAS, 256, 391. -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 13-Aug-1996