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FarUltraviolet Observations of NGC 3516 using the Hopkins Ultraviolet G. A. Kriss, B. R. Espey, J. H. Krolik, Z. Tsvetanov, W. Zheng, and A. F. Davidsen
 

Summary: Far­Ultraviolet Observations of NGC 3516 using the Hopkins Ultraviolet
Telescope
G. A. Kriss, B. R. Espey, J. H. Krolik, Z. Tsvetanov, W. Zheng, and A. F. Davidsen
Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218
ABSTRACT
We observed the Seyfert 1 galaxy NGC 3516 twice during the flight of Astro­2
using the Hopkins Ultraviolet Telescope aboard the space shuttle Endeavour in March
1995. Simultaneous X­ray observations were performed with ASCA. Our far­ultraviolet
spectra cover the spectral range 820--1840 š A with a resolution of 2--4 š A. No significant
variations were found between the two observations. The total spectrum shows a red
continuum, f š ¸ š \Gamma1:89 , with an observed flux of 2:2 \Theta 10 \Gamma14 erg cm \Gamma2 s \Gamma1 š A \Gamma1 at 1450
š A, slightly above the historical mean. Intrinsic absorption in Lyman fi is visible as well
as absorption from O vi ––1032; 1038, N v ––1239; 1243, Si iv ––1394; 1403, and C iv
––1548; 1551. The UV absorption lines are far weaker than is usual for NGC 3516, and
also lie closer to the emission line redshift rather than showing the blueshift typical
of these lines when they are strong. The neutral hydrogen absorption, however, is
blueshifted by 400 km s \Gamma1 relative to the systemic velocity, and it is opaque at the
Lyman limit. The sharpness of the cutoff indicates a low effective Doppler parameter,
b ! 20 km s \Gamma1 . For b = 10 km s \Gamma1 the derived intrinsic column is 3:5 \Theta 10 17 cm \Gamma2 .
As in NGC 4151, a single warm absorber cannot produce the strong absorption visible

  

Source: Henry, Richard C.- Department of Physics and Astronomy, Johns Hopkins University

 

Collections: Physics