DOUBLE GALAXIES

 

 

KARCHENTSEV DOUBLE GALAXIES

 

Karachentsev's Catalog of Double Galaxies includes 603 double systems. In recent years the radial velocities of galaxies have been defined and the mass determinations of the components of galaxies have been derived. With very few exceptions spectrophotometric data for double galaxies are not available.

Pairs of galaxies are the simplest systems of galaxies. The study of such systems is of great interest because  of the different rates of evolution and gravitational and star burst effects. There is a strong evidence the double galaxies arised together and their evolution elapsed via parallel ways.

We have begun an investigation of star formation in different types of galaxies  -  HSBG,  Arakelian-  and Markarian galaxies using IRAS  data. Pairs of galaxies are the only reason to look for some differences in the star formation of the components of the same system.  For the beginning we have chosen Karachentsev pairs of galaxies (KarGs). The overall list of Karachentsev contains 603 pairs.

a)   The IR KarGs are a sample of normal galaxies with on average high IR luminosities - <LgLIR> ~ 43.60;

b)   We might expect an increasing or constant SFR than a decreasing one. This could be explained with the influence of the neighbour in the pair;

c)   To detect IR fluxes from KarGs there have to exist 1E+3 to 1E+8  Mo  dust in  these  galaxies.  For the arbitrary  ratio gas/dust ca. 100 this leads to 1E+5 - 1E+10 Mo gas;

d)    The star formation activity in Karachentsev double galaxies is lower then in Arakelian-,  HSBG  or  Markarian ones and is similar to the SFR in bright spiral galaxies in Virgo.

 

 

OUR RESEARCH ON SPECTROPHOTOMETRY OF KARCHENTSEV DOUBLE GALAXIES

 

We carried out a detailed spectrophotometry covering the red spectrum along the Ηα line on spectra with a dispersion of 100-200 Å.mm-1 (a resolution of 5-10 Å) for the following galaxies: Karachentsev 288a, b (Petrov et al, 1981), Karachentsev 466a = NGC 5929 (Yankulova et al, 1980), Karachentsev 570b = NGC 7339 (Petrov et al., 1984), and Karachentsev 578a = NGC7537 (Petrov et al., 1983).

Spectrophotometric data for 31 galaxies from the list of Karachentsev (1972), based on ca. 100 scans in the region of λλ 3700-5300 Å obtained with the 5-m Hale telescope of the Mount Palomar Observatory, incorporating a 512-channel scanner and  spectral resolution  about 4 Å per channel were provided.  Except for Kar 97a, the studied galaxies have weak emission lines.

Estimation of the electron density after the method of Minkowski and Osterbrock (1959) and determination of the ion content and chemical composition of the emitting gas has been suggested by Peimbert (1968). The studied sample of double galaxies includes only one active object, Kar 93b = I Zw 55, which is a Seyfert galaxy of NGC 1068 type.

The full text (PETROV G.T., KOVACHEV B.J., MINEVA V. A., Ap & Spa. Sci., v. 116, 333-340, 1985) in PDF format could be found here.



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PUBLISHED PAPERS

 

 

1.      PETROV G.T., GOLEV V. K., YANKULOVA I. M., C. r. Acad. Sci. Bulg., v. 34, 461-464, 1981                 “Physical conditions in the double galaxies with emission lines. Mrk 171a, b”

2.      YANKULOVA I. M., PETROV G. T., GOLEV V. K., Astr. Tsirc. No. 1169, 1-3, 1981 (in Russian)                “Some spectrophotometric data about the double galaxy NGC 3690 + IC 694”

3.      PETROV G. T., KOVACHEV B. J., MINEVA V. A., Ap & Spa. Sci., v. 116, 333-340, 1985                          “Some spectrophotometric data for 31 galaxies from Karachentsev list”

4.      PETROV G. T., MINEVA V. A., KYAZUMOV G. A., C. r. Acad. Sci. Bulg., v. 38, 291-294, 1985           “Rotation, mass and physical conditions in the nucleus of the spiral galaxy NGC 7339 (Karachentsev 570b) ”

5.      PETROV G. & MINEVA V., C.r., v. 45, No. 8, 1992                                                                                     “Star Formation in Karachentsev's double galaxies”



Created by G. T. Petrov