Search Publications
Gas Kinematics in Lyα Nebulae
Kelson, Daniel D.; Davé, Romeel; Yang, Yujin +4 more
Exploring the origin of Lyα nebulae ("blobs") at high redshift requires measurements of their gas kinematics that are impossible with only the resonant, optically thick Lyα line. To define gas motions relative to the systemic velocity of the blob, the Lyα line must be compared with an optically thin line like Hα λ6563, which is not much altered by…
Concerning the Classical Cepheid VI C Wesenheit Function's Strong Metallicity Dependence
Gieren, W.; Turner, D.; Majaess, D.
Evidence is presented which supports findings that the classical Cepheid VI C period Wesenheit function is relatively insensitive to metallicity. The viability of a recently advocated strong metallicity dependence was evaluated by applying the proposed correction (γ = -0.8 mag dex-1) to distances established for the Magella…
A First Measurement of the Proper Motion of the Leo II Dwarf Spheroidal Galaxy
Lépine, Sébastien; Rich, R. Michael; Kuijken, Konrad +1 more
We use 14 year baseline images obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST) to derive a proper motion for one of the Milky Way's most distant dwarf spheroidal companions, Leo II, relative to an extragalactic background reference frame. Astrometric measurements are performed in the effective point-sp…
A Spitzer Infrared Spectrograph Detection of Crystalline Silicates in a Protostellar Envelope
Fischer, William J.; Hartmann, Lee; Calvet, Nuria +12 more
We present the Spitzer Space Telescope Infrared Spectrograph spectrum of the Orion A protostar HOPS-68. The mid-infrared spectrum reveals crystalline substructure at 11.1, 16.1, 18.8, 23.6, 27.9, and 33.6 µm superimposed on the broad 9.7 and 18 µm amorphous silicate features; the substructure is well matched by the presence of the oliv…
The Surface Composition of Large Kuiper Belt Object 2007 OR10
Brown, M. E.; Burgasser, A. J.; Fraser, W. C.
We present photometry and spectra of the large Kuiper belt object 2007 OR10. The data show significant near-infrared absorption features due to water ice. While most objects in the Kuiper belt with water ice absorption this prominent have the optically neutral colors of water ice, 2007 OR10 is among the reddest Kuiper belt objects known. One other…
The Widespread Occurrence of Water Vapor in the Circumstellar Envelopes of Carbon-rich Asymptotic Giant Branch Stars: First Results from a Survey with Herschel/HIFI
Waters, L. B. F. M.; Olofsson, H.; Marston, A. P. +16 more
We report the preliminary results of a survey for water vapor in a sample of eight C stars with large mid-IR continuum fluxes: V384 Per, CIT 6, V Hya, Y CVn, IRAS 15194-5115, V Cyg, S Cep, and IRC+40540. This survey, performed using the HIFI instrument on board the Herschel Space Observatory, entailed observations of the lowest transitions of both…
Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1
Quinet, P.; García, J.; Kallman, T. R. +5 more
We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM - Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O I atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the o…
Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera
Okada, Yoko; Hattori, Kaori; Nagayoshi, Tsutomu +13 more
We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target …
A Study of Gravitational Lens Chromaticity with the Hubble Space Telescope
Kochanek, C. S.; Muñoz, J. A.; Falco, E. E. +2 more
We report Hubble Space Telescope observations of six gravitational lenses with the Advanced Camera for Surveys. We measured the flux ratios between the lensed images in seven filters from 8140 Å to 2200 Å. In three of the systems, HE0512-3329, B1600+434, and H1413+117, we were able to construct UV extinction curves partially overlapping the 2175 Å…
HST-COS Observations of Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse Shock
Smith, Nathan; Pun, Chun S. J.; France, Kevin +18 more
We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Δv ~ 300 km s-1) emission lines from the circumstellar ring, broad (Δv ~ 10-20 × 103 km s-1) emission lines from the reverse shock, a…