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J/ApJ/453/48        VI photometry of HST faint field galaxies (Driver+ 1995)

The contribution of late-type/irregulars to the faint galaxy counts from Hubble Space Telescope Medium Deep Survey images Driver S.P., Windhorst R.A., Griffiths R.E. <Astrophys. J. 453, 48 (1995)> =1995ApJ...453...48D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Morphology Mission_Name: HST Keywords: galaxies: evolution - galaxies: fundamental parameters - galaxies: irregular - galaxies: luminosity function, mass function - galaxies: statistics - surveys Abstract: We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0=<Imag<22.0mag. We compare the global properties of the ellipticals and early- and late-type spirals and find a non-negligible fraction (13/144) of compact blue [(V-I)<1.0mag] systems with r1/4 profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LFs) and a standard cosmology. Conversely, late-type/irregulars show a steeply rising differential number count with slope (δlogN/δm)=0.64±0.1. No-evolution models based on the Loveday et al. (1992ApJ...390..338L) and Marzke et al. (1994AJ....108..437M & 1994ApJ...428...43M) local luminosity functions underpredict the late-type/irregular counts by 1.0 and 0.5dex, respectively, at Imag=21.75mag. Examination of the irregulars alone shows that ∼50% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF (α≃-1.0) is ruled out for these types, and an LF with a steep faint end (α≃-1.5) is suggested. If multiple core structure indicates recent star formation, then the observed excess of faint blue field galaxies is likely a result of et evolutionary processes acting on a steep field LF for late-type/irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z≥0.5 at mI=21.75mag. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2 80 144 A complete catalog of HST field galaxies obtained from the six MDS fields
See also: J/AJ/112/359 : Galaxies in the Hubble Deep Field (van den Bergh+ 1996) J/AJ/112/1335 : Hubble Deep Field observations (Williams+ 1996) Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 3 I3 --- ID Object identification number 5- 9 A5 --- MDS MDS field name 11 I1 --- WFPC2 WFPC2 CCD number (1=PC, 2, 3, 4=WFC) 13- 17 F5.1 pix Xpos Original X pixel position on the WFPC2 CCD 19- 23 F5.1 pix Ypos Original Y pixel position on the WFPC2 CCD 25- 26 I2 h RAh Right ascension (J2000.0) 28- 29 I2 min RAm Right ascension (J2000.0) 31- 35 F5.2 s RAs Right ascension (J2000.0) (1) 37 A1 --- DE- Declination sign 38- 39 I2 deg DEd Declination (J2000.0) 41- 42 I2 arcmin DEm Declination (J2000.0) 44- 47 F4.1 arcsec DEs Declination (J2000.0) (1) 49- 53 F5.2 mag Imag Total I814 magnitude 55- 58 F4.2 mag V-I Total (V-I) color 60- 64 F5.2 mag/arcsec2 SuBr Central I-band surface brightness within a radius of 0.2" 66- 70 F5.2 mag (V-I)c Central (V-I) color within a radius of 0.2" 72- 75 F4.2 --- eps Image ellipticity e=1-a/b, computed from the outermost isophote 77 I1 --- Mtype Galaxy type (2) 79- 80 I2 pix Radius Aperture radius used to determine the I-band magnitude
Note (1): Relative RAs and DEs should be accurate to within 0.1". Absolute WFPC2 astrometry is only accurate to ∼0.5"-1."Note (2): 0 = E, 1 = 5a, 2 = 5b, 3 = 5c, 4 = 5d, 5 = Irr, 6 = peculiar Note (2): 0 = E, 1 = 5a, 2 = 5b, 3 = 5c, 4 = 5d, 5 = Irr, 6 = peculiar
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 14-Feb-1997
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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