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91.
We present a study of the nearby Seyfert galaxy NGC 3982 using optical,infrared and X-ray data acquired by SDSS,Spitzer and Chandra.Our main results are as follows:(1) A simple stellar population synthesis on the nuclear and circumnuclear SDSS spectra gives unambiguous evidence of young stellar components in both the nuclear and circumnuclear regions.(2) The Spitzer Infrared Spectrograph (IRS) spectrum of the central region (~3") shows a power-law continuum,a silicate emission feature at 9.7 μm,and significant PAH emission features at 7.7,8.6,11.3 and 12.7/zm,suggesting the coexistence of AGN and starburst activities in the central region of NGC 3982.(3) We estimate the star formation rate (SFR) of the circumnuclear (~5"-20") region from the Ha luminosity to be for the active nucleus of NGC 3982 from radio to X-ray,and obtain a bolometric luminosity of Lbol=4.5×1042 erg s-1,corresponding to an Eddington ratio (Lbol/LEdd) of 0.014.The HST image of NGC 3982 shows a nuclear mini-spiral between the circumnuclear starforming region and the nucleus,which could be the channel through which gas is transported to the supermassive black hole from the circumnuclear star-forming region. 相似文献
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Joris Gerssen Konrad Kuijken Michael R. Merrifield 《Monthly notices of the Royal Astronomical Society》1999,306(4):926-930
The pattern speed is a defining parameter of any barred galaxy. A large number of model-dependent techniques have therefore been developed to derive the pattern speed. However, the only model-independent technique for measuring this quantity – the Tremaine–Weinberg method – has hitherto been applied to just one case, the SB0 galaxy NGC 936. In this paper, we apply the technique to a second system, the SBa galaxy NGC 4596. The resulting estimate for the pattern speed is Ωp =52±13 km s−1 kpc−1 . This result is corroborated by a spectrum obtained along the major axis of the bar in this system. The corotation radius associated with this pattern speed lies just beyond the end of the bar indicating a fast bar. Combining the bar major-axis spectra with data obtained from a Hubble Space Telescope WFPC2 image, we also find strong evidence for a nuclear disc. 相似文献
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Y. M. Pihlstrm J. E. Conway R. S. Booth P. J. Diamond B. Koribalski 《New Astronomy Reviews》1999,43(8-10)
We report on observations, with sub-parsec resolution, of neutral hydrogen seen in absorption in the λ=21 cm line against the nucleus of the active spiral galaxy NGC 5793. The absorption line consists of three components separated in both location as well as velocity. We derive HI column densities of 2×1022 cm−2 assuming a gas spin temperature of 100 K. For the first time we are able to reliably estimate the HI cloud sizes (≈15 pc) and atomic gas densities (≈200 cm−3). Our results suggest that the HI gas is not associated with the <10 pc region which presumably contains the H2O masers, but it is more distant from the nucleus, and is probably associated with the r1 kpc gas seen in CO. 相似文献
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We start with the hypotheses that the cluster space is limited by an ellipsoid with a semiprincipal axis directed to the observer and that the star density inside of concentric ellipsodal layers remains constant, although varying from layer to layer. It results that the mean star mass at the periphery of the cluster is 0.59 Sun masses smaller than that at the center. 相似文献