Search Publications
Mira kinematics in the post-Hipparcos era
Schilbach, E.; Kharchenko, N.; Malkov, O. +1 more
The complete data set of Mira variables from the 4th edition of the General Catalog of Variable Stars was analyzed and supplemented by the proper motions and radial velocities presently available for Miras. The resulting sample of 724 Miras with periods between 78 and 612 days contains proper motions reduced to the Hipparcos system, radial velocit…
XMM-Newton observations of MR Vel/RX J0925.7-4758
Motch, C.; Neiner, C.; Bearda, H.
We report on XMM-Newton observations of the galactic supersoft X-ray source
Complex Formation History of the Lenticular Galaxies with Stellar Counterrotation: NGC 4138 and NGC 4550
Sil'chenko, O. K.; Afanasiev, V. L.
Two lenticular galaxies with counterrotating stellar components in their disks have been studied with the Multi-Pupil Fiber Spectrograph of the 6 m telescope (at the Special Astrophysical Observatory). In NGC 4138 the nucleus is certainly chemically distinct, with the central concentration of magnesium enhancement marginally exceeding that of iron…
A Hubble Space Telescope Polarization Study of Dust in the η Carinae Homunculus
Panagia, N.; Gull, T. R.; Walsh, J. R. +5 more
New high-resolution polarization images of the η Car Homunculus have been obtained with the Hubble Space Telescope (HST) at several wavelengths spanning the near-UV to the near-IR. With these images, taken with WFPC2 and NICMOS, we have been able to compare the polarization properties of the Homunculus at different wavelengths. We confirm that the…
Total solar and spectral irradiance variations from solar cycles 21 to 23
Fröhlich, C.; Pap, J. M.; Floyd, L. +2 more
Total solar and UV irradiances have been measured from various space platforms for more than two decades. More recently, observations of the "Variability of solar IRradiance and Gravity Oscillations" (VIRGO) experiment on SOHO provided information about spectral irradiance variations in the near-UV at 402 nm, visible at 500 nm, and near-IR at 862 …
The pulsational behaviour of the rapidly oscillating Ap star HD 122970 during two photometric multisite campaigns
Granzer, T.; Handler, G.; Garrido, R. +11 more
We undertook two time-series photometric multisite campaigns for the rapidly oscillating Ap star HD 122970. The first one, conducted in 1998, resulted in 119h of data and in the detection of three pulsation frequencies. The presence of possible further modes which held the promise of deriving a mode identification motivated a second worldwide camp…
What Happened to the NGC 6251 Counterjet?
Jones, Dayton L.; Wehrle, Ann E.
We have used the Very Long Baseline Array to produce a high dynamic range image of the nucleus of NGC 6251 at 1.6 GHz and snapshot images at 5.0, 8.4, and 15.3 GHz to search for emission from a parsec-scale counterjet. Previous VLBI images at 1.6 GHz have set a lower limit for the jet/counterjet brightness ratio near the core at about 80:1, which …
Discovery of a Star Formation Region in Abell 2052
Koekemoer, Anton M.; Baum, Stefi A.; Sparks, William B. +2 more
We report the discovery of an ultraviolet filament detected in a new Space Telescope Imaging Spectrograph (STIS) NUV-MAMA image of the cD galaxy UGC 9799, located in the cooling-flow cluster Abell 2052 and host to the radio source 3C 317. The filament is ~2 kpc in length and is located at a distance of ~4 kpc from the nucleus along a north-south a…
A Prominent Apparition of Neptune's South Polar Feature
Lockwood, G. W.; Rages, Kathy; Hammel, Heidi B.
During the last week of June 2001, a bright apparition of Neptune's South Polar Feature (SPF) at 70°S was observed to develop and decay in less than 30 hours, displaying contrast of ∼2.5 at 619 nm. Assuming that the same SPF was observed on two consecutive rotations of Neptune, the feature moved eastward at 3.2±1.8° hr -1 (130±80 m s
Stokes parameters of resonance lines scattered by a moving, magnetic medium. Theory of the two-level atom
Raouafi, N. -E.
The aim of the present work is to present theoretical results on the Stokes parameters of a resonance spectral line, scattered by moving atoms (or ions) in the presence of a local magnetic field. We assume that the scattered line is sensitive to the Hanle effect due to the magnetic field and also to Doppler redistribution due to the atomic motions…