Search Publications
A Search for Molecular Gas in the Nucleus of M87 and Implications for the Fueling of Supermassive Black Holes
Beuther, Henrik; Walter, Fabian; Tan, Jonathan C. +1 more
Supermassive black holes in giant elliptical galaxies are remarkably faint given their expected accretion rates. This motivates models of radiatively inefficient accretion due to either ion-electron thermal decoupling, generation of outflows that inhibit accretion, or settling of gas to a gravitationally unstable disk that forms stars in preferenc…
Observations of the north polar water ice annulus on Mars using THEMIS and TES
Bandfield, Joshua L.; Castaño, Rebecca; Titus, Timothy N. +2 more
The Martian seasonal CO2 ice caps advance and retreat each year. In the spring, as the CO2 cap gradually retreats, it leaves behind an extensive defrosting zone from the solid CO2 cap to the location where all CO2 frost has sublimated. We have been studying this phenomenon in the north polar region using…
Emission from Very Small Grains and PAH Molecules in Monte Carlo Radiation Transfer Codes: Application to the Edge-On Disk of Gomez's Hamburger
Wood, Kenneth; Robitaille, Thomas; Draine, Bruce T. +1 more
We have modeled optical to far-infrared images, photometry, and spectroscopy of the object known as Gomez's Hamburger. We reproduce the images and spectrum with an edge-on disk of mass 0.3 M⊙ and radius 1600 AU, surrounding an A0 III star at a distance of 280 pc. Our mass estimate is in excellent agreement with recent CO observations. H…
Jovian-like aurorae on Saturn
Bunce, Emma J.; Melin, Henrik; Miller, Steve +5 more
Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its …
A New FUSE Survey of Interstellar HD
Snow, Theodore P.; Destree, Joshua D.; Rachford, Brian L. +5 more
We have used archival FUSE data to complete a survey of interstellar HD in 41 lines of sight with a wide range of extinctions. This follow-up to an earlier survey was made to further assess the utility of HD as a cosmological probe; to analyze the HD formation process; and to see what trends with other interstellar properties were present in the d…
Off-Nuclear Star Formation and Obscured Activity in the Luminous Infrared Galaxy NGC 2623
Sanders, D. B.; Surace, J. A.; Armus, L. +13 more
New optical Hubble Space Telescope (HST), Spitzer Space Telescope, and XMM observations of the luminous infrared galaxy (LIRG) NGC 2623 are presented. This galaxy was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The prominent 3.2 kpc southern extension to the nucleus has been resolved by HST observations into ~100 star …
Complex structure within Saturn's infrared aurora
Drossart, Pierre; Dougherty, Michele K.; Bunce, Emma J. +14 more
The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H3+ …
GRB 070610: A Curious Galactic Transient
Cenko, S. B.; Campana, S.; Price, P. A. +23 more
GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive …
The Structure of the Local Interstellar Medium. V. Electron Densities
Redfield, Seth; Falcon, Ross E.
We present a comprehensive survey of C II* absorption detections toward stars within 100 pc in order to measure the distribution of electron densities present in the local interstellar medium (LISM). Using high spectral resolution observations obtained by GHRS and STIS on board HST, we searched for all detections of LISM C II* absorption. We ident…
Coronal Rotation at Solar Minimum from UV Observations
Giordano, S.; Mancuso, S.
The observations of the UVCS SOHO instrument from 1996 May to 1997 May have been analyzed to reconstruct intensity time series of the O VI 1032 Å and H I Lyα 1216 Å spectral lines at different coronal heliolatitudes from 1.5 to 3.0 R⊙ from Sun center. At solar minimum, some features persist for several rotations, thus allowing analysis …