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XMM-Newton observations of the Seyfert 1 galaxy Mrk 335
Gondoin, P.; Santos-Lleo, M.; Orr, A. +1 more
We report on an XMM-Newton observation of the Seyfert 1 galaxy Mrk 335 performed in December 2000. The power law component of its spectrum above 2 keV has a photon index Gamma =2.3 much steeper than that of a ``normal'' Seyfert 1 galaxy. A broad spectral feature is observed around 6.0 keV (+/-1 keV) that can be fitted by a relativistic emission pr…
The Nucleus of Comet 22P/Kopff and Its Inner Coma
Jorda, L.; Lamy, P. L.; A'Hearn, M. F. +3 more
We report the detection of the nucleus of Comet 22P/Kopff with the Planetary Camera of the Hubble Space Telescope (HST) and with the Infrared Camera of the Infrared Space Observatory (ISOCAM). The HST observations were performed on 18 July 1996, 16 days after its perihelion passage of 2 July 1996, when it was at Rh=1.59 AU from the Sun …
The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III
Da Costa, G. S.; Armandroff, T. E.; Caldwell, Nelson
The Hubble Space Telescope Wide Field Planetary Camera 2 has been used to image Andromeda III, a dwarf spheroidal (dSph) companion to M31. The resulting color-magnitude diagrams (CMDs) reveal for the first time the morphology of the horizontal branch (HB) in this dwarf galaxy. We find that like Andromeda I and Andromeda II, and like most of the Ga…
Variation of the low-degree solar acoustic mode parameters over the solar cycle
Jiménez-Reyes, S. J.; Jiménez, A.; Roca Cortés, T.
VIRGO/SPM is a helioseismic sunphotometer on board SOHO that observes the disk-integrated sunlight irradiance at three different colors (red, green, and blue). The data obtained for SPM since the beginning of the SOHO mission, April 1996, to March 2001 have been used to study the differences of the p-mode parameters during the solar activity cycle…
Searching for the Physical Drivers of Eigenvector 1: From Quasars to Nanoquasars
Marziani, P.; Zamanov, R.
We point out an analogy between two accreting white dwarfs (CH Cyg and MWC 560) with jets and powerful quasars. In spite of the enormous difference in the mass of the central object (a factor ~107), the emission lines are strikingly similar to those of I Zw 1 (the prototype ``narrow-line Seyfert 1'' nucleus whose spectrum is widely used…
The Afterglow and Complex Environment of the Optically Dim Burst GRB 980613
McMahon, Richard G.; Halpern, Jules P.; Hjorth, Jens +15 more
We report the identification of the optical afterglow of GRB 980613 in R- and I-band images obtained between 16 and 48 hr after the gamma-ray burst. Early near-infrared (NIR) H and K' observations are also reported. The afterglow was optically faint (R~23) at discovery but did not exhibit an unusually rapid decay (power-law decay slope α<1.8 at…
Analysis of colour-magnitude diagrams of rich LMC clusters: NGC 1831
Santiago, B. X.; Kerber, L. O.; Valls-Gabaud, D. +1 more
We present the analysis of a deep colour-magnitude diagram (CMD) of NGC 1831, a rich star cluster in the LMC. The data were obtained with HST/WFPC2 in the F555W ( ~ V) and F814W ( ~ I) filters, reaching m555 ~ 25. We discuss and apply a method of correcting the CMD for sampling incompleteness and field star contamination. Efficient use …
Extreme-Ultraviolet Absorption Lines in Lyα Forest Absorbers and the Oxygen Abundance in the Intergalactic Medium
Kriss, Gerard A.; Zheng, Wei; Davidsen, Arthur F. +2 more
We create stacked composite absorption spectra from Hubble Space Telescope Faint Object Spectrograph data from four quasi-stellar objects to search for absorption lines in the extreme-ultraviolet wavelength region associated with Lyα forest absorbers in the redshift range 1.6<z<2.9. We successfully detect O V λ630 in Lyα absorbers throughout…
The Angular Expansion and Distance of the Planetary Nebula BD +30°3639
Borkowski, Kazimierz J.; Harrington, J. Patrick; Li, Jianyang
The WFPC2 camera aboard the Hubble Space Telescope was used to obtain images of the planetary nebula BD +30°3639 at two epochs separated by 5.663 yr. The expansion of the nebula in the Hα and [N II] bands has been measured using several methods. Detailed expansion maps for both emission lines were constructed from nearly 200 almost independent fea…
The WR+OB Progenitor RY Scuti: Intensive Spectroscopy of Its Compact Double-Ring Nebula
Smith, Nathan; Gehrz, Robert D.; Balick, Bruce +2 more
We present a detailed spectroscopic analysis of the peculiar nebula around RY Scuti using data from the Space Telescope Imaging Spectrograph (STIS) and various ground-based observatories. This massive contact binary may represent a rapid evolutionary phase in transition to a short-period WR+OB system, and it is surrounded by a young nebula with un…