Search Publications
New Observational Constraints on the υ Andromedae System with Data from the Hubble Space Telescope and Hobby-Eberly Telescope
Butler, R. Paul; Benedict, G. Fritz; McArthur, Barbara E. +4 more
We have used high-cadence radial velocity (RV) measurements from the Hobby-Eberly Telescope with existing velocities from the Lick, Elodie, Harlan J. Smith, and Whipple 60'' telescopes combined with astrometric data from the Hubble Space Telescope Fine Guidance Sensors to refine the orbital parameters and determine the orbital inclinations and pos…
Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-velocity Upflows?
De Pontieu, Bart; McIntosh, Scott W.
Since the discovery of quasi-periodic propagating oscillations with periods of order 3-10 minutes in coronal loops with TRACE and SOHO/EIT (and later with STEREO/EUVI and Hinode/EIS), they have been almost universally interpreted as evidence for propagating slow-mode magnetoacoustic waves in the low plasma β coronal environment. Here we show that …
A Seismic Signature of a Second Dynamo?
Chaplin, William J.; Basu, Sarbani; Garcia, Rafael A. +5 more
The Sun is a variable star whose magnetic activity varies most perceptibly on a timescale of approximately 11 years. However, significant variation is also observed on much shorter timescales. We observe a quasi-biennial (2 year) signal in the natural oscillation frequencies of the Sun. The oscillation frequencies are sensitive probes of the solar…
AKARI IRC Infrared 2.5-5 µm Spectroscopy of a Large Sample of Luminous Infrared Galaxies
Nakagawa, Takao; Shirahata, Mai; Imanishi, Masatoshi +2 more
We present the results of our systematic infrared 2.5-5 µm spectroscopy of 60 luminous infrared galaxies (LIRGs) with infrared luminosities L IR = 1011-1012 L sun and 54 ultraluminous infrared galaxies (ULIRGs) with L IR >= 1012 L sun, using the AKARI Infrared Ca…
Nonlinear Propagation of Alfvén Waves Driven by Observed Photospheric Motions: Application to the Coronal Heating and Spicule Formation
Matsumoto, Takuma; Shibata, Kazunari
We have performed MHD simulations of Alfvén wave propagation along an open flux tube in the solar atmosphere. In our numerical model, Alfvén waves are generated by the photospheric granular motion. As the wave generator, we used a derived temporal spectrum of the photospheric granular motion from G-band movies of Hinode/Solar Optical Telescope. It…
The CFHTLS-Deep Catalog of Interacting Galaxies. I. Merger Rate Evolution to z = 1.2
Sullivan, M.; Bridge, C. R.; Carlberg, R. G.
We present the rest-frame optical galaxy merger fraction between 0.2 < z < 1.2, as a function of stellar mass and optical luminosity, as observed by the Canada-France-Hawaii Telescope Legacy Deep Survey (CFHTLS-Deep). We developed a new classification scheme to identify major galaxy-galaxy mergers based on the presence of tidal tails and bri…
The Most Massive Galaxies at 3.0 <= z < 4.0 in the Newfirm Medium-band Survey: Properties and Improved Constraints on the Stellar Mass Function
van Dokkum, Pieter G.; Franx, Marijn; Illingworth, Garth D. +10 more
We use the optical to mid-infrared coverage of the NEWFIRM Medium-Band Survey (NMBS) to characterize, for the first time, the properties of a mass-complete sample of 14 galaxies at 3.0 <= z < 4.0 with M star>2.5 × 1011 M sun, and to derive significantly more accurate measurements of the high-mass end of th…
Testing Automated Solar Flare Forecasting with 13 Years of Michelson Doppler Imager Magnetograms
Hoeksema, J. T.; Mason, J. P.
Flare occurrence is statistically associated with changes in several characteristics of the line-of-sight magnetic field in solar active regions (ARs). We calculated magnetic measures throughout the disk passage of 1075 ARs spanning solar cycle 23 to find a statistical relationship between the solar magnetic field and flares. This expansive study …
The XMM Cluster Survey: Active Galactic Nuclei and Starburst Galaxies in XMMXCS J2215.9-1738 at z = 1.46
Hilton, Matt; Stott, John P.; Stanford, S. Adam +11 more
We use Chandra X-ray and Spitzer infrared (IR) observations to explore the active galactic nucleus (AGN) and starburst populations of XMMXCS J2215.9-1738 at z = 1.46, one of the most distant spectroscopically confirmed galaxy clusters known. The high-resolution X-ray imaging reveals that the cluster emission is contaminated by point sources that w…
Radial Velocity Offsets Due to Mass Outflows and Extinction in Active Galactic Nuclei
Kraemer, S. B.; Crenshaw, D. M.; Mushotzky, R. F. +2 more
We present a study of the radial velocity offsets between narrow emission lines and host galaxy lines (stellar absorption and H I 21 cm emission) in Seyfert galaxies with observed redshifts less than 0.043. We find that 35% of the Seyferts in the sample show [O III] emission lines with blueshifts with respect to their host galaxies exceeding 50 km…