Search Publications
The Evolution of Early-Type Red Galaxies with the GEMS Survey: Luminosity-Size and Stellar Mass-Size Relations Since z=1
Bell, Eric F.; Somerville, Rachel S.; Wisotzki, Lutz +14 more
We combine imaging from the Hubble Space Telescope Advanced Camera for Surveys, as part of the GEMS (Galaxy Evolution from Morphologies and SEDs) survey, with redshifts and rest-frame quantities from COMBO-17 to study the evolution of morphologically early-type galaxies with red colors since z=1. From 0.5d×0.5d imaging, we draw a large sample of 7…
Evidence for Spectropolarimetric Diversity in Type Ia Supernovae
Filippenko, Alexei V.; Foley, Ryan J.; Leonard, Douglas C. +2 more
We present single-epoch, postmaximum spectropolarimetry of four Type Ia supernovae (SNe Ia) that span a range of spectral and photometric properties: SN 2002bf and SN 2004dt exhibit unusually high-velocity (HV) absorption lines. SN 1997dt is probably somewhat subluminous, and SN 2003du is slightly overluminous. We detect polarization modulations a…
Deep ACS Imaging of the Halo of NGC 5128: Reaching the Horizontal Branch
Greggio, Laura; Peng, Eric W.; Rejkuba, Marina +2 more
Using the Hubble Space Telescope (HST) Wide Field Camera (WFC) of the Advanced Camera for Surveys (ACS), we have obtained deep (V, I) photometry of an outer halo field in NGC 5128, to a limiting magnitude of I~=29. Our photometry directly reveals the core helium burning stellar population (the ``red clump'' or horizontal branch) in a giant E/S0 ga…
Discovery of the Accretion-powered Millisecond X-Ray Pulsar IGR J00291+5934
Chakrabarty, Deepto; Galloway, Duncan K.; Markwardt, Craig B. +2 more
We report on observations of the sixth accretion-powered millisecond pulsar, IGR J00291+5934, with the Rossi X-Ray Timing Explorer. The source is a faint recurrent X-ray transient initially identified by the International Gamma-Ray Astrophysics Laboratory. The 599 Hz (1.67 ms) pulsation had a fractional rms amplitude of 8% in the 2-20 keV range, a…
On the Nature of Dark Extreme Ultraviolet Structures Seen by SOHO/EIT and TRACE
Heinzel, P.; Anzer, U.
Spectral lines in the extreme ultraviolet (EUV) observed on the Sun can originate either from the hot corona or the cooler chromosphere to corona transition region. In the present paper we concentrate on coronal lines and in particular on iron lines at 171, 195, and 284 Å, which have been frequently observed by the Solar and Heliospheric Observato…
Rest-Frame Ultraviolet-to-Optical Properties of Galaxies at z ~ 6 and z ~ 5 in the Hubble Ultra Deep Field: From Hubble to Spitzer
Ouchi, Masami; Papovich, Casey; Dickinson, Mark +11 more
We use data from the first epoch of observations with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope for the Great Observatories Origins Deep Survey (GOODS) to detect and study a collection of Lyman break galaxies at z~6-5 in the Hubble Ultra Deep Field (HUDF), six of which have spectroscopic confirmation. At these redshifts, IRAC…
Hubble Space Telescope Observations of Heavy Elements in Metal-Poor Galactic Halo Stars
Beers, Timothy C.; Truran, James W.; Burles, Scott +6 more
We present new abundance determinations of neutron-capture elements Ge, Zr, Os, Ir, and Pt in a sample of 11 metal-poor (-3.1<=[Fe/H]<=-1.6) Galactic halo giant stars, based on Hubble Space Telescope UV and Keck I optical high-resolution spectroscopy. The stellar sample is dominated by r-process-rich stars such as the well-studied CS 22892-0…
Black Hole Masses and Host Galaxy Evolution of Radio-Loud Active Galactic Nuclei
van der Marel, Roeland P.; Urry, C. Megan; Lira, Paulina +2 more
We report stellar velocity dispersion measurements for a sample of 28 active galactic nucleus (AGN) host galaxies, including our previous work. Using the mass-dispersion (M•-σ) and the fundamental plane relations, we estimate the black hole mass for a sample of 66 BL Lac objects and investigate the role of black hole mass in the energet…
Seismic Emission from the Solar Flares of 2003 October 28 and 29
Lindsey, C.; Donea, A. -C.
We report the detection of seismic waves emitted from powerful solar flares that occurred in NOAA Active Region 10486 on 2003 October 28 and 29. We used helioseismic holography to image the seismic sources of the waves. This technique was previously used to image the source of seismic emission from the large solar flare of 1996 July 9. Egression p…
Helioseismic Determination of the Solar Rotation Axis
Giles, P.; Beck, J. G.
Time-distance helioseismology analysis of Dopplergrams from the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory spacecraft provides a very accurate measurement of meridional flows. This shows a sinusoidal variation with a period of 1 yr and was identified by P. Giles to be due to an error in the determination of…