Search Publications
An Impulsive Solar Flare Accompanied by a Cusplike Structure in Soft X-Rays
Grechnev, V. V.; Nakajima, H.
A detailed analysis of an impulsive solar flare of 1999 September 17 was carried out using microwave, soft, and hard X-ray data. The flare showed pronounced nonthermal processes and was accompanied by a cusplike structure in soft X-rays in the decay phase, manifesting features attributed to different flare models. The results suggest that importan…
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…
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 …
The Gravitational Lens CFRS 03.1077
Le Fèvre, O.; Crampton, David; Lilly, S. J. +3 more
An exquisite gravitational arc with a radius of 2.1" has been discovered around the z=0.938 field elliptical galaxy CFRS 03.1077 during HST observations of Canada-France Redshift Survey (CFRS) fields. Spectroscopic observations of the arc show that the redshift of the resolved lensed galaxy is z=2.941. This gravitational lens source system is well…
Heating in Coronal Funnels by Ion Cyclotron Waves
Li, Xing
Plasma heating by ion cyclotron waves in rapidly expanding flow tubes in the transition region, referred to as coronal funnels, is investigated in a three-fluid plasma consisting of protons, electrons, and α-particles. Ion cyclotron waves are able to heat the plasma from 6×104 to 106 K over a distance range of 104 …
Correlating Transition Region Explosive Events with Extreme-Ultraviolet Brightenings
Reeves, Katharine K.; Winebarger, Amy R.; Updike, Adria C.
Frequent small-scale reconnection events have been proposed as a possible mechanism to heat the solar corona. It has not yet been demonstrated, however, that the smallest reconnection events can heat the plasma to coronal temperatures. In this Letter, we use explosive events in the spectral line C IV λ1548 observed by the Solar Ultraviolet Measure…
The Nondamped Nature of 12 Low-Redshift Damped Lyα Candidate Systems
Turnshek, David A.; Rao, Sandhya M.
Hubble Space Telescope (HST) UV spectroscopy of 12 candidate low-redshift damped Lyα (DLA) systems in 11 quasi-stellar objects (z=0.103 in Q0054+144, z=0.969 and z=0.987 in Q0302-223, z=0.478 in Q0454-220, z=1.476 in Q1047+550, z=1.070 in Q1206+459, z=1.228 in Q1247+267, z=0.399 in Q1318+290B, z=0.519 in Q1329+412, z=0.276 in Q1451-375, z=0.204 in…
Metallicity Determinations from Ultraviolet-Visual Spectrophotometry. I. The Test Sample
Chavez, M.; Di Marcantonio, P.; Morossi, C. +2 more
New visual spectrophotometric observations of non-supergiant solar neighborhood stars are combined with IUE Newly Extracted Spectra (INES) energy distributions in order to derive their overall metallicities, [M/H]. This fundamental parameter, together with effective temperature and apparent angular diameter, is obtained by applying the flux-fittin…
Jet-triggered Type Ia Supernovae in Radio Galaxies?
Capetti, Alessandro
We report the serendipitous discovery of a supernova (SN) in the nearby radio galaxy 3C 78. Observations obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope show, at a distance of 0.54" (300 pc) from the galaxy nucleus, a second bright source, not present in previous images. As this source was fortuitously co…
Far Ultraviolet Spectroscopic Explorer Observations of O VI Overlying the Scutum Supershell
Savage, B. D.; Sembach, K. R.; Sterling, N. C. +2 more
We present Far Ultraviolet Spectroscopic Explorer observations of the B0 III star HD 177989 (l=17.8d, b=-11.9d, d=4.9 kpc). This line of sight passes through the high-latitude outflow from the Scutum supershell (GS 018-04+44), a structure that lies at a kinematic distance of ~3.5 kpc and spans ~5° in diameter. The O VI λ1031.93 line is compared wi…