The relation between the neutral and the ionized gas in NGC 5252

被引:18
作者
Prieto, MA
Freudling, W
机构
[1] SPACE TELESCOPE EUROPEAN COORDINATING FACIL,GARCHING,GERMANY
[2] EUROPEAN SO OBSERV,D-85748 GARCHING,GERMANY
关键词
galaxies; haloes; individual; NGC; 5252; ISM galaxies; Seyfert; radio lines;
D O I
10.1093/mnras/279.1.63
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The gas of the Seyfert 2 galaxy NGC 5252 consists of an ionized bicone of gas and a region of neutral gas which fills the regions outside the ionized bicone. We present new HI maps of the neutral components with a spatial resolution which exceeds previously available maps by a factor of 2. In addition, the ionized component was imaged in the H alpha 6563-Angstrom emission line. A comparison of the physical properties of both extended gas systems leads to the following results. (1) HI column densities range from 2 to 5 x 10(20) cm(-2), in fair agreement with those found in the HII gas. (2) The two components of the gas follow a similar rotation pattern with comparable velocity amplitudes of about 100 km s(-1), At the central region, both the ionized and neutral gas are counter-rotating with a peak amplitude of about 150 km s(-1). These similarities of the two components of the gas suggest a physical connection between them. The most plausible configuration is a series of ring structures surrounding the optical body of the galaxy. A previous suggestion of apolar ring can virtually be ruled out by the new data. The complexity of the gas system suggests an external origin for the gas in NGC 5252 such as a merger with a gas-rich system. Finally, a search for molecular material in the nuclear region of the galaxy led to an upper limit on the central H-2 mass content of 2 x 10(8) h(-2) M. within the central 4 h(-1) kpc (11 arcsec). The low molecular content is consistent with an unusually high nuclear extinction if the material is highly concentrated in the central region.
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页码:63 / 71
页数:13
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