Search Publications
The Central Region of Barred Galaxies: Molecular Environment, Starbursts, and Secular Evolution
Scoville, Nick; Jogee, Shardha; Kenney, Jeffrey D. P.
Stellar bars drive gas into the circumnuclear (CN) region of galaxies. To investigate the fate of the CN gas and star formation (SF), we study a sample of barred nonstarbursts and starbursts with high-resolution CO, optical, Hα, radio continuum, Brγ, and HST data, and find the following. (1) The inner kiloparsec of bars differs markedly from the o…
A Jovian-Mass Planet in Microlensing Event OGLE-2005-BLG-071
Bennett, D. P.; Gal-Yam, A.; Soszyński, I. +34 more
We report the discovery of a several-Jupiter-mass planetary companion to the primary lens star in microlensing event OGLE-2005-BLG-071. Precise (<~1%) photometry at the peak of the event yields an extremely high signal-to-noise ratio detection of a deviation from the light curve expected from an isolated lens. The planetary character of this de…
Solar-like Oscillations in α Centauri B
Butler, R. Paul; Bedding, Timothy R.; Marcy, Geoffrey W. +6 more
We have made velocity observations of the star α Centauri B from two sites, allowing us to identify 37 oscillation modes with l=0-3. Fitting to these modes gives the large and small frequency separations as a function of frequency. The mode lifetime, as measured from the scatter of the oscillation frequencies about a smooth trend, is similar to th…
The Luminosity, Stellar Mass, and Number Density Evolution of Field Galaxies of Known Morphology from z = 0.5 to 3
Papovich, Casey; Conselice, Christopher J.; Blackburne, Jeffrey A.
The evolution of rest-frame B-band luminosities, stellar masses, and number densities of field galaxies in the Hubble Deep Fields North and South are studied as a function of rest-frame B-band morphological type out to redshift z~3 using a sample of 1231 I<27 galaxies with spectroscopic and photometric redshifts. We find that the comoving and r…
Longitudinal Magnetic Field Changes Accompanying Solar Flares
Harvey, J. W.; Sudol, J. J.
We have used Global Oscillation Network Group (GONG) magnetograms to characterize the changes in the photospheric longitudinal magnetic field during 15 X-class solar flares. An abrupt, significant, and persistent change in the magnetic field occurred in at least one location within the flaring active region during each event. We have identified a …
Evolution since z = 1 of the Morphology-Density Relation for Galaxies
Smith, Graham P.; Treu, Tommaso; Ellis, Richard S. +2 more
We measure the morphology-density relation of galaxies at z=1 across the full 3 orders of magnitude in projected galaxy density available in low-redshift studies. Our study adopts techniques that are comparable with those applied at lower redshifts, allowing a direct investigation of how the morphological segregation of galaxies has evolved over t…
A Deep Chandra Survey of the Globular Cluster 47 Tucanae: Catalog of Point Sources
Heinke, C. O.; Cohn, H. N.; Lugger, P. M. +5 more
We have detected 300 X-ray sources within the half-mass radius (2.79 arcmin) of the globular cluster 47 Tucanae in a deep (281 ks) Chandra exposure. We perform photometry and simple spectral fitting for our detected sources and construct luminosity functions, X-ray color-magnitude, and color-color diagrams. Eighty-seven X-ray sources show variabil…
Discovery of an X-Ray-luminous Galaxy Cluster at z=1.4
Böhringer, H.; Rosati, P.; Schwope, A. +4 more
We report the discovery of a massive, X-ray-luminous cluster of galaxies at z=1.393, the most distant X-ray-selected cluster found to date. XMMU J2235.3-2557 was serendipitously detected as an extended X-ray source in an archival XMM-Newton observation of NGC 7314. VLT FORS2 R- and z-band snapshot imaging reveals an overdensity of red galaxies in …
Super-Helium-rich Populations and the Origin of Extreme Horizontal-Branch Stars in Globular Clusters
Joo, Seok-Joo; Han, Sang-Il; Ree, Chang H. +7 more
Recent observations for the color-magnitude diagrams (CMDs) of the massive globular cluster ω Centauri have shown that it has a striking double main sequence (MS), with a minority population of bluer and fainter MS stars well separated from a majority population of MS stars. Here we confirm, with the most up-to-date Y2 isochrones, that …
Keck Spectroscopy of Distant GOODS Spheroidal Galaxies: Downsizing in a Hierarchical Universe
Treu, Tommaso; van Dokkum, Pieter G.; Ellis, Richard S. +1 more
We analyze the evolution of the fundamental plane for 141 field spheroidal galaxies in the redshift range 0.2<z<1.2, selected morphologically to a magnitude limit F850LP=22.43 in the northern field of the Great Observatories Origins Deep Survey. For massive galaxies, we find that the bulk of the star formation was completed prior to z=2. How…