Search Publications
A New Probe of the Planet-forming Region in T Tauri Disks
Herczeg, Gregory J.; Russell, Ray W.; Qi, Chunhua +9 more
We present new observations of the far-ultraviolet (FUV; 1100-2200 Å) radiation field and the near- to mid-IR (3-13.5 µm) spectral energy distribution (SED) of a sample of T Tauri stars selected on the basis of bright molecular disks (GM Aur, DM Tau, and LkCa 15). In each source we find evidence for Lyα-induced H2 fluorescence and…
The XMM-Newton and BeppoSAX view of the Ultra Luminous Infrared Galaxy MKN 231
Cappi, M.; Franceschini, A.; Piconcelli, E. +11 more
We discuss XMM-Newton and BeppoSAX observations of MKN 231, the lowest-redshift Broad Absorption Line (BAL) QSO known so far and one of the best-studied Ultra Luminous Infrared Galaxies. By combining the XMM-Newton spectral resolution and the high-energy bandpass of BeppoSAX we have been able to study in more detail than previously possible its 0.…
E+A Galaxies and the Formation of Early-Type Galaxies at z~0
Lauer, Tod R.; Zabludoff, Ann I.; Zaritsky, Dennis +2 more
E+A galaxies, whose spectra have deep Balmer absorption lines but no significant [O II] emission, are the best candidates for an evolutionary link between star-forming, gas-rich galaxies and quiescent, gas-poor galaxies. However, their current morphologies are not well known. We present Hubble Space Telescope WFPC2 observations of the five bluest …
Coronal Heating through Braiding of Magnetic Field Lines
Peter, Hardi; Gudiksen, Boris V.; Nordlund, Åke
Cool stars such as our Sun are surrounded by a million degree hot outer atmosphere, the corona. For more than 60 years, the physical nature of the processes heating the corona to temperatures well in excess of those on the stellar surface have remained puzzling. Recent progress in observational techniques and numerical modeling now opens a new win…
Imaging X-Ray, Optical, and Infrared Observations of the Transient Anomalous X-Ray Pulsar XTE J1810-197
Gotthelf, E. V.; Halpern, J. P.; Buxton, M. +1 more
We report X-ray imaging, timing, and spectral studies of XTE J1810-197, a 5.54 s pulsar discovered by Ibrahim and coworkers in recent Rossi X-Ray Timing Explorer (RXTE) observations. In a set of short exposures with the High Resolution Camera on board the Chandra X-Ray Observatory, we detect a strongly modulated signal (55%+/-4% pulsed fraction) w…
Ultraviolet Emission from the Millisecond Pulsar J0437-4715
Pavlov, George G.; Kargaltsev, Oleg; Romani, Roger W.
We observed PSR J0437-4715 with the FUV-MAMA detector of the Space Telescope Imaging Spectrometer (STIS) to measure the pulsar's spectrum and pulsations. For the first time, UV emission from a millisecond pulsar has been detected. The measured flux, (2.0+/-0.2)×10-15 ergs s-1 cm-2 in the 1150-1700 Å range, correspo…
Hubble Space Telescope Imaging of HD 44179, The Red Rectangle
Gull, T. R.; Bond, Howard E.; Van Winckel, Hans +1 more
We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and deep ground-based images of the Red Rectangle (RR), a bipolar proto-planetary nebula associated with the post-AGB binary system HD 44179. The high-resolution HST images reveal complex new structures, many of them unique to this object. The RR nebula is dominated by a discont…
Spaceship Earth Observations of the Easter 2001 Solar Particle Event
Dröge, Wolfgang; Evenson, Paul; Ruffolo, David +5 more
The largest relativistic (~1 GeV) solar proton event of the current solar activity cycle occurred on Easter 2001 (April 15). This was the first such event to be observed by Spaceship Earth, an 11-station network of neutron monitors optimized for measuring the angular distribution of solar cosmic rays. We derive the particle density and anisotropy …
Evidence for Gradual External Reconnection before Explosive Eruption of a Solar Filament
Moore, Ronald L.; Sterling, Alphonse C.
We observe a slowly evolving quiet-region solar eruption of 1999 April 18, using extreme-ultraviolet (EUV) images from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) and soft X-ray images from the Soft X-ray Telescope (SXT) on Yohkoh. Using difference images, in which an early image is subtracted from later images…
Astrophysical supplements to the ASCC-2.5. II. Membership probabilities in 520 Galactic open cluster sky areas
Scholz, R. -D.; Piskunov, A. E.; Kharchenko, N. V. +2 more
We present a catalogue (CSOCA ) of stars residing in 520 Galactic open cluster sky areas which is the result of the kinematic (proper motion) and photometric member selection of stars listed in the homogeneous All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5). We describe the structure and contents of the catalogue, the selection procedur…