Search Publications
Physical Conditions in Circumstellar Gas Surrounding SN 1987A 12 Years after Outburst
Gull, Theodore R.; Pun, Chun S. J.; Lundqvist, Peter +3 more
Two-dimensional spectra of SN 1987A were obtained on 1998 November 14-15 (4282 days after outburst) with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The slit sampled portions of the inner circumstellar ring at the east and west ansae as well as small sections of both the northern and southern outer ri…
Resolving the Stellar Populations in a z=4 Lensed Galaxy
Bunker, Andrew J.; Davis, Marc; Moustakas, Leonidas A.
We present deep near-infrared Keck Near-Infrared Camera (NIRC) imaging of a recently discovered z=4.04 galaxy. This is lensed by the rich foreground cluster Abell 2390 (z~0.23) into highly magnified arcs 3"-5" in length. Our H and K' band NIRC imaging allows us to map the Balmer+4000 Å break amplitude. In combination with high-quality a…
Structure of the Solar Core: Effect of Asymmetry of Peak Profiles
Christensen-Dalsgaard, J.; Provost, J.; Berthomieu, G. +8 more
Recent studies have established that peaks in solar oscillation power spectra are not Lorentzian in shape but have a distinct asymmetry. Fitting a symmetric Lorentzian profile to the peaks, therefore, produces a shift in frequency of the modes. Accurate determination of low-frequency modes is essential to infer the structure of the solar core by i…
Hubble Space Telescope Photometry of the Dwarf Spheroidal Galaxy ESO 410-G005
Dolphin, Andrew E.; Grebel, Eva K.; Seitzer, Patrick +7 more
We present Hubble Space Telescope WFPC2 imaging of the nearby low surface brightness dwarf spheroidal galaxy ESO 410-G005, which has been resolved into stars for the first time. The resulting color-magnitude diagram for about 2500 stars shows a red giant branch with a tip at I=22.4+/-0.15 mag, which yields a distance of DMW=1.9+/-0.2 Mp…
Pre-Orion Cores in the Trifid Nebula
Cernicharo, José; Lefloch, Bertrand
The Trifid Nebula is a young H II region undergoing a burst of star formation. This article reports on far-infrared and millimeter continuum and line observations of several massive and bright protostellar sources in the vicinity of the exciting star of the nebula, just behind the ionization front. These objects are probably young protostars (clas…
Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and the Implications for Cygnus X-2
Misra, Ranjeev; Bhattacharyya, Sudip; Thampan, Arun V. +1 more
We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model for the spectrum of the X-ray emission from the disk that is parameterized by the mass accretion rate, the color temperature, …
Observational Evidence of Supershell Blowout in GS 018-04+44: The Scutum Supershell
Savage, Blair D.; Haffner, L. Matthew; Benjamin, Robert A. +2 more
Emission in the H I 21 cm line has been mapped for a region of the Galaxy that includes two known supershells, GS 018-04+44 and GS 034-06+65. We focus on the GS 018-04+44, hereafter referred to as the Scutum Supershell, which is an elongated shell about 5 deg in diameter extending to -7 deg below the Galactic plane. The Scutum shell lies at a kine…
Mid-Ultraviolet Determination of Elliptical Galaxy Abundances and Ages
Ferguson, Henry C.; Lotz, Jennifer M.; Bohlin, Ralph C.
We investigate the effects of abundance and age on the mid-UV spectra and Mg2 strengths of stellar populations using simple population synthesis models. These models are used to constrain the star formation history of four nearby elliptical galaxies and spiral bulges. The mid-UV (1800-3200 Å) light of evolved stellar populations (>1 …
Compositional Variation on the Surface of Centaur 8405 Asbolus
Brown, R. H.; Buie, M. W.; Campins, H. +3 more
Near-infrared 1-2 µm spectra of the Centaur 8405 Asbolus (1995 GO) have been obtained using the Hubble Space Telescope near-infrared camera and multiobject spectrometer. Strong and variable absorption features indicate a significantly inhomogeneous surface characterized by water ice mixed with additional unknown constituents. Over a 1.7 hr i…
Probing the Interstellar Medium in Early-Type Galaxies withInfrared Space Observatory Observations
Helou, G.; Lu, N.; Malhotra, S. +9 more
Four IRAS-detected early-type galaxies were observed with the Infrared Space Observatory (ISO). With the exception of the 15 µm image of NGC 1052, the mid-IR images of NGC 1052, NGC 1155, NGC 5866, and NGC 6958 at 4.5, 7, and 15 µm show extended emission. Mid-IR emission from NGC 1052, NGC 1155, and NGC 6958 follows a de Vaucouleurs pr…