Stellar populations in the nuclear regions of nearby radio galaxies

被引:45
作者
Aretxaga, I
Terlevich, E
Terlevich, RJ
Cotter, G
Díaz, AI
机构
[1] Inst Nacl Astrofis Opt & Elect, Puebla 72000, Mexico
[2] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
[3] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England
[4] Univ Autonoma Madrid, Dept Fis Teor C11, Madrid, Spain
关键词
galaxies : active; galaxies : starburst; galaxies : stellar content;
D O I
10.1046/j.1365-8711.2001.04463.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present optical spectra of the nuclei of seven luminous (P-178MHz greater than or similar to 10(25) W Hz(-1) Sr-1) nearby (z < 0.08) radio galaxies, which mostly correspond to the FR II class. In two cases, Hydra A and 3C 285, the Balmer and <lambda>4000-Angstrom break indices constrain the spectral types and luminosity classes of the stars involved, revealing that the blue spectra are dominated by blue supergiant and/or giant stars. The ages derived for the last burst of star formation in Hydra A are between 7 and 40 Myr, and in 3C 285 about 10 Myr. The rest of the narrow-line radio galaxies (four) have a lambda 4000-Angstrom break and metallic indices consistent with those of elliptical galaxies. The only broad-line radio galaxy in our sample, 3C 382, has a strong featureless blue continuum and broad emission lines that dilute the underlying blue stellar spectra. We are able to detect the Ca II triplet in absorption in the seven objects, with good quality data for only four of them. The strengths of the absorptions are similar to those found in normal elliptical galaxies, but these values are consistent both with stellar populations of roughly similar ages (as derived from the Balmer absorption and break strengths) and with mixed young+old populations.
引用
收藏
页码:636 / 648
页数:13
相关论文
共 96 条
[1]   CALIBRATION OF METALLICITY EFFECTS ON INTEGRATED COLORS OF GLOBULAR CLUSTERS AND EARLY-TYPE GALAXIES [J].
AARONSON, M ;
COHEN, JG ;
MOULD, J ;
MALKAN, M .
ASTROPHYSICAL JOURNAL, 1978, 223 (03) :824-834
[2]   CLASSIFICATION PARAMETERS FOR THE EMISSION-LINE SPECTRA OF EXTRA-GALACTIC OBJECTS [J].
BALDWIN, JA ;
PHILLIPS, MM .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 1981, 93 (551) :5-19
[3]  
BARBIER D, 1955, CONTRIB I ASTROPHY A, V178, P8
[4]   EXTENSIVE X-RAY MONITORING OF THE BROAD-LINE RADIO GALAXY 3C-382 [J].
BARR, P ;
GIOMMI, P .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1992, 255 (03) :495-501
[5]   EXTENDED OPTICAL-LINE EMITTING GAS IN POWERFUL RADIO GALAXIES - STATISTICAL PROPERTIES AND PHYSICAL CONDITIONS [J].
BAUM, SA ;
HECKMAN, T .
ASTROPHYSICAL JOURNAL, 1989, 336 (02) :681-701
[6]   SPECTROSCOPY OF EMISSION-LINE NEBULAE IN POWERFUL RADIO GALAXIES - INTERPRETATION [J].
BAUM, SA ;
HECKMAN, TM ;
VANBREUGEL, W .
ASTROPHYSICAL JOURNAL, 1992, 389 (01) :208-222
[7]   EXTENDED OPTICAL-LINE-EMITTING GAS IN RADIO GALAXIES - BROAD-BAND OPTICAL NARROW-BAND OPTICAL, AND RADIO IMAGING OF A REPRESENTATIVE SAMPLE [J].
BAUM, SA ;
HECKMAN, T ;
BRIDLE, A ;
VANBREUGEL, W ;
MILEY, G .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1988, 68 (04) :643-714
[8]   A STUDY OF FRII RADIO GALAXIES WITH ZETA-LESS-THAN-0.15 .1. HIGH-RESOLUTION MAPS OF 8 SOURCES AT 3.6 CM [J].
BLACK, ARS ;
BAUM, SA ;
LEAHY, JP ;
PERLEY, RA ;
RILEY, JM ;
SCHEUER, PAG .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1992, 256 (02) :186-208
[9]  
Bressan A, 1996, ASTRON ASTROPHYS, V311, P425
[10]  
CHALONGE D, 1956, ANN ASTROPHYS, V19, P258