Search Publications
The Cepheid Distance to NGC 1637: A Direct Test of the Expanding Photosphere Method Distance to SN 1999em
Leonard, Douglas C.; Tanvir, Nial R.; Kanbur, Shashi M. +1 more
Type II-plateau supernovae (SNe II-P) are the classic variety of core-collapse events that result from isolated, massive stars with thick hydrogen envelopes intact at the time of explosion. Their distances are now routinely estimated through two techniques: the expanding photosphere method (EPM), a primary distance-determining method, and the rece…
The Nature of E+A Galaxies in Intermediate-Redshift Clusters
Franx, Marijn; Kelson, Daniel D.; Tran, Kim-Vy H. +2 more
Combining Hubble Space Telescope WFPC2 mosaics with extensive ground-based spectroscopy, we study the nature of E+A galaxies in three intermediate-redshift clusters (z=0.33, 0.58, and 0.83). From a sample of ~500 confirmed cluster members, we isolate 46 E+A candidates to determine the E+A fraction and study their physical properties. Spectral type…
Coronal dimming and the coronal mass ejection onset
Simnett, G. M.; Harrison, R. A.; Bryans, P. +1 more
A set of five observations of extreme-ultraviolet (EUV) coronal dimming associated with coronal mass ejection (CME) activity is examined. Using spectroscopic data, plasma characteristics across a broad range of temperatures from 20 000 K to 2 million K are determined. The dimming events are found to coincide in time, and to coincide spatially, wit…
Forecasting solar wind structures and shock arrival times using an ensemble of models
Dryer, M.; Smith, Z.; Fry, C. D. +3 more
Forecasting the time of arrival at Earth of interplanetary shocks following solar metric type II activity is an important first step in the establishment of an operational space weather prediction system. The quality of the forecasts is of utmost importance. The performances of the shock time of arrival (STOA) and interplanetary shock propagation …
Acceleration of coronal mass ejections
Chen, James; Krall, Jonathan
The acceleration of coronal mass ejections (CMEs) is examined focusing on three specific questions raised by observations: (1) what determines the height beyond which a CME exhibits no rapid acceleration, (2) why is the main acceleration of CMEs typically limited to below 2-3 solar radii, and (3) are distinct mechanisms required to explain the app…
Complex C: A Low-Metallicity, High-Velocity Cloud Plunging into the Milky Way
Tripp, Todd M.; Jenkins, Edward B.; Linsky, J. L. +8 more
We present evidence that high-velocity cloud (HVC) complex C is a low-metallicity gas cloud that is plunging toward the disk and beginning to interact with the ambient gas that surrounds the Milky Way. This evidence begins with a new high-resolution (7 km s-1 FWHM) echelle spectrum of 3C 351 obtained with the Space Telescope Imaging Spe…
Jupiter's polar auroral emissions
Kim, J.; Clarke, J. T.; Cowley, S. W. H. +3 more
This paper reports a study of Jupiter's polar auroral emissions observed in an extended series of FUV images. They were obtained on seven days, during winter 2000-2001, with the STIS camera on board the Hubble Space Telescope. The fixed pointing yielded highly accurate and consistent tracking of emisson features as Jupiter rotated, allowing the an…
Deep Hubble Space Telescope Imaging of IC 1613. II. The Star Formation History
Dolphin, Andrew E.; Skillman, Evan D.; Cole, Andrew A. +5 more
We have taken deep images of an outlying field in the Local Group dwarf irregular galaxy IC 1613 with the WFPC2 aboard the Hubble Space Telescope in the standard broadband F555W (V, 8 orbits) and F814W (I, 16 orbits) filters. The photometry reaches to V=27.7 (MV=+3.4) and I=27.1 (MI=+2.8) at the 50% completeness level, the de…
Fe II/Mg II Emission-Line Ratio in High-Redshift Quasars
Vestergaard, M.; Dietrich, M.; Appenzeller, I. +1 more
We present results of the analysis of near-infrared spectroscopic observations of six high-redshift quasars (z>~4), emphasizing the measurement of the ultraviolet Fe II/Mg II emission-line strength to estimate the beginning of intense star formation in the early universe. To investigate the evolution of the Fe II/Mg II ratio over a wider range …
Remote infrared observations of parent volatiles in comets: A window on the early solar system
Dello Russo, N.; Mumma, M. J.; DiSanti, M. A. +3 more
Organic volatiles and water in Oort Cloud comets were investigated at infrared wavelengths. The detected species include H 2O, CO, CH 3OH, CH 4, C 2H 2, C 2H 6, OCS, HCN, NH 3, and H 2CO. Several daughter fragments (CN, OH, NH 2, etc.) are…