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2. First observations of an R Coronae Borealis star with the space telescope imaging spectrograph: RY Sagittarii near maximum light

Author

Clayton, Geoffrey C, Ayres, T.R, Lawson, Warrick A, Drilling, John S, Woitke, P, Asplund, Martin, Clayton, Geoffrey C, Ayres, T.R, Lawson, Warrick A, Drilling, John S, Woitke, P, and Asplund, Martin

Abstract

We describe the far-UV (1140-1740 Å) spectrum of the hydrogen-deficient R Coronae Borealis (RCB) star RY Sgr, obtained near maximum light (pulsational phase ~0.1) by the Space Telescope Imaging Spectrograph (STIS) on Hubble Space Telescope. The far-UV spectrum shows a photospheric continuum rising steeply toward longer wavelengths and two prominent emission features at the shorter wavelengths: C II lambda1335 and Cl I lambda1351 (the latter is radiatively fluoresced by the 10 times stronger C II multiplet). We also find evidence for CO A-X 4th-positive system absorption band heads and possible weak CO fluorescent emissions pumped by C II lambda1335, but the inferred column densities are low (~few times 10^16 cm^-2), consistent with formation in a warm (~5000 K) atmospheric layer. The detection of CO molecules, if confirmed, would be significant, because they are thought to play a key role in the dust ejection episodes of RCB stars through the initiation of "molecular cooling catastrophes."

Published
1999

3. STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI. XI. INTENSIVE MONITORING OF THE ULTRAVIOLET SPECTRUM OF NGC 7469

Author

Wanders, I., Peterson, Bradley M., Alloin, D., Ayres, T.R., Clavel, J., Crenshaw, D. Michael, Horne, K., Kriss, Gerard A., Krolik, Julian Henry, Malkan, Matthew A., Netzer, Hagai, O'Brien, Paul T., Reichert, G.A., Rodriguez-Pascual, P.M., Wamsteker, W., Alexander, T., Anderson, K. S.J., Benitez, E., Bochkarev, N.G., Burenkov, A.N., Cheng, F.-Z., Collier, S.J., Comastri, A., Dietrich, M., Dultzin-Hacyan, D., Espey, B.R., Filippenko, A. V., Gaskell, C. Martin, George, I.M., Goad, M.R., Ho, L.C., Kaspi, Shai, Kollatschny, W., Korista, Kirk T., Laor, Ari, MacAlpine, G.M., Mignoli, M., Morris, S.L., Nandra, K., Penton, S., Pogge, Richard William, Ptak, R.L., Rodriguez-Espinoza, J.M., Santos-Lleo, M., Shapovalova, A.I., Shull, J.M., Snedden, Stephanie A., Sparke, L.S., Stirpe, G.M., Sun, W.-H., Turner, T.J., Ulrich, M.-H., Wang, T.-G., Wei, C., Welsh, W.F., Xue, S.-J., Zhou, Z.-L., Wanders, I., Peterson, Bradley M., Alloin, D., Ayres, T.R., Clavel, J., Crenshaw, D. Michael, Horne, K., Kriss, Gerard A., Krolik, Julian Henry, Malkan, Matthew A., Netzer, Hagai, O'Brien, Paul T., Reichert, G.A., Rodriguez-Pascual, P.M., Wamsteker, W., Alexander, T., Anderson, K. S.J., Benitez, E., Bochkarev, N.G., Burenkov, A.N., Cheng, F.-Z., Collier, S.J., Comastri, A., Dietrich, M., Dultzin-Hacyan, D., Espey, B.R., Filippenko, A. V., Gaskell, C. Martin, George, I.M., Goad, M.R., Ho, L.C., Kaspi, Shai, Kollatschny, W., Korista, Kirk T., Laor, Ari, MacAlpine, G.M., Mignoli, M., Morris, S.L., Nandra, K., Penton, S., Pogge, Richard William, Ptak, R.L., Rodriguez-Espinoza, J.M., Santos-Lleo, M., Shapovalova, A.I., Shull, J.M., Snedden, Stephanie A., Sparke, L.S., Stirpe, G.M., Sun, W.-H., Turner, T.J., Ulrich, M.-H., Wang, T.-G., Wei, C., Welsh, W.F., Xue, S.-J., and Zhou, Z.-L.

Published
1997

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