NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-25 T04:13:48 PDT
Help | Comment | NED Home

For refcode 1997ApJS..108..229H:
Retrieve 33 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
1997ApJS..108..229H THE DISKS OF GALAXIES WITH SEYFERT AND STARBURST NUCLEI. I. NEAR-INFRARED COLORS AND COLOR GRADIENTS L. K. HUNT Centro per l'Astronomia Infrarossa e lo Studio del Mezro Interstellare, CNR, Largo Enrico Fermi 5, I-50125 Firenze, Italy; hunt@arcetri.astro.it M. A. MALKAN Department of Astronomy, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90024; malkan@bonnie.astro.ucla.edu M. SALVATI Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy; salvati@arcetri.astro.il N. MANDOLESI AND E. PALAZZI Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, via Gobetti 101, I-40126 Bologna, Italy; reno@botesl.tesre.bo.cnr.it, eliana@tonno.tesre.bo.cnr.it AND R. WADE Rutherford Appleton Laboratory, CLRC, Chilton, Didcot, Oxon OX11 OQX, England; rwade@tn.rl.ac.uk Received 1996 March 11; accepted 1996 July 29 ABSTRACT We present near-infrared (NIR) broadband and color images of 26 galaxies that host Seyfert 1, Seyfert 2, or starburst nuclei (SBNs). The study is focused on properties of the host galaxies rather than their nuclei, and to this end, careful attention is paid to photometric accuracy and to reliable measurements of the low surface brightness outer disk. Inspection of the elliptically averaged radial brightness and color profiles reveals that (1) the NIR mean colors of the inner and outer disks of Seyfert and starburst galaxies are consistent with those of a normal late-type stellar population and do not differ significantly with activity class; (2) the color gradients in the outer disks are similar both in sign and in magnitude to those observed in normal spirals; (3) red "ridges" in the inner parts of the J - H profile are evident in the majority of SBNs, but only in a few type 1 Seyferts and in no type 2's; (4) circumnuclear blue "dips" in the J - H profile are seen only in type 2 Seyferts. We then construct color images and find ridges, rings, and filaments, not evident in the broadband images, in the inner disks of SBNs and in NGC 7469, a Seyfert 1. The application of a simple model to these features yields evidence of both dust extinction and excess 2 micron emission. Color-color diagrams of individual pixels confirm these results and also show that the stellar mix in most of the Seyfert 2's comprises a conspicuous contribution from an intermediate-age [(3-5) x 10^8^ yr] population. It appears that ongoing star formation in the inner disks of SBNs is signaled by the presence of dust (and gas); the absence of such features in both Seyfert types implies that star formation episodes are either absent or very old. However, while the blue colors of Seyfert 2's suggest that a burst of star formation did, in fact, occur not more than 10^9^ yr ago, the normal colors of Seyfert 1's imply that any star-forming episodes must be significantly older. Subject headings: dust, extinction - galaxies: photometry - galaxies: Seyfert - galaxies: starburst - galaxies: structure - infrared: galaxies
Retrieve 33 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home