Search Publications
Disk Accretion in the 10 MYR Old T Tauri Stars TW Hydrae and Hen 3-600A
Briceño, C.; Calvet, N.; Muzerolle, J. +2 more
We have found that two members of the TW Hydrae association, TW Hydrae and Hen 3-600A, are still actively accreting, based on the ballistic infall signature of their broad Hα emission profiles. We present the first quantitative analysis of accretion in these objects and conclude that the same accretion mechanisms which operate in the well-studied …
A Hubble Space Telescope Snapshot Survey of Proto-Planetary Nebula Candidates: Two Types of Axisymmetric Reflection Nebulosities
Ueta, Toshiya; Meixner, Margaret; Bobrowsky, Matthew
We report the results from an optical imaging survey of proto-planetary nebula candidates using the Hubble Space Telescope (HST). The goals of the survey were to image low surface brightness optical reflection nebulosities around proto-planetary nebulae and to investigate the distribution of the circumstellar dust, which scatters the star light fr…
Chandra Discovery of a 100 kiloparsec X-Ray Jet in PKS 0637-752
Elvis, M.; Birkinshaw, M.; Worrall, D. M. +18 more
The quasar PKS 0637-752, the first celestial X-ray target of the Chandra X-Ray Observatory, has revealed asymmetric X-ray structure extending from 3" to 12" west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z=0.651, the jet is the largest (>~100 k…
Bars and Warps Traced by the Molecular Gas in the Seyfert 2 Galaxy NGC 1068
Genzel, R.; Tacconi, L. J.; Schinnerer, E. +2 more
We present new interferometer observations of the 12CO (1-0) and 12CO (2-1) line emission of NGC 1068 with a resolution of 0.7". The molecular gas in the inner 5" is resolved into a ring with two bright knots east and west of the nuclear continuum emission. For the first time in NGC 1068, we can trace molecular gas at ~0.18" …
Evidence for a Supernova in Reanalyzed Optical and Near-Infrared Images of GRB 970228
Galama, T. J.; Kouveliotou, C.; Armus, L. +14 more
We present B-, V-, RC-, IC-, J-, H-, K-, and K'-band observations of the optical transient (OT) associated with GRB 970228, based on a reanalysis of previously used images and unpublished data. In order to minimize calibration differences, we have collected and analyzed most of the photometry and consistently determined the m…
Hubble Space Telescope Observations of 10 Two-Image Gravitational Lenses
Peng, C. Y.; Keeton, C. R.; Kochanek, C. S. +6 more
We report on a program to obtain Hubble Space Telescope (HST) observations of galaxy-mass gravitational lens systems at optical and infrared wavelengths. Here we discuss the properties of 10 two-image gravitational lens systems (Q0142-100=UM 673, B0218+357, SBS 0909+532, BRI 0952-0115, LBQS 1009-0252, Q1017-207=J03.13, B1030+074, HE 1104-1805, Q12…
Deeply Penetrating Banded Zonal Flows in the Solar Convection Zone
Thompson, M. J.; Howe, R.; Hill, F. +5 more
Helioseismic observations have detected small temporal variations of the rotation rate below the solar surface that correspond to the so-called ``torsional oscillations'' known from Doppler measurements of the surface. These appear as bands of slower- and faster-than-average rotation moving equatorward. Here we establish, using complementary helio…
EIT Waves and Fast-Mode Propagation in the Solar Corona
Wang, Y. -M.
During the onset of coronal mass ejections, a front of enhanced EUV emission is sometimes seen to propagate away from a flaring active region across the solar disk. We present model simulations to test the hypothesis that these transients (called ``EIT waves'') represent fast-mode MHD waves. The distribution of the magnetosonic velocity vf
Active and Eruptive Prominences and Their Relationship to Coronal Mass Ejections
Gilbert, Holly R.; Holzer, Thomas E.; Burkepile, Joan T. +1 more
In order to understand better the dynamical processes in the solar atmosphere that are associated with coronal mass ejections (CMEs), we have carried out a study of prominence activity using Hα observations obtained at the Mauna Loa Solar Observatory (MLSO). After developing clear definitions of active prominences (APs) and eruptive prominences (E…
Massive Star Formation and Evolution in Starburst Galaxies: Mid-infrared Spectroscopy with the ISO Short Wavelength Spectrometer
Förster Schreiber, Natascha M.; Lutz, Dieter; Spoon, Henrik W. W. +4 more
We present new Infrared Space Observatory Short Wavelength Spectrometer data for a sample of 27 starburst galaxies, and with these data we examine the issues of formation and evolution of the most massive stars in starburst galaxies. Using starburst models which incorporate time evolution, new stellar atmosphere models for massive stars, and a sta…