Search Publications
The Nature and Geometry of the Light Echo from SN 2006X
Crotts, Arlin P. S.; Yourdon, David
We report on the discovery of the geometry producing the light echo emanating from supernova 2006X, a nearby but underluminous Type Ia supernova (SN Ia) in M100 (=NGC 4321). This offers a rare chance to study the environment of a SN Ia. Contrary to previous reports, there is little evidence of a circumstellar component in the light echo morphology…
Modeling X-Ray Loops and EUV "Moss" in an Active Region Core
Winebarger, Amy R.; Warren, Harry P.; Falconer, David A.
The soft X-ray intensity of loops in active region cores and the corresponding footpoint, or moss, intensity observed in the EUV remain steady for several hours of observation. The steadiness of the emission has prompted many to suggest that the heating in these loops must also be steady, although no direct comparison between the observed X-ray an…
Theoretical Fits of the δ Cephei Light, Radius, and Radial Velocity Curves
Marconi, Marcella; Bono, Giuseppe; Natale, Giovanni
We present a theoretical investigation of the light, radius, and radial velocity variations of the prototype δ Cephei. We find that the best-fit model accounts for luminosity and velocity amplitudes with an accuracy better than 0.8 σ, and for the radius amplitude with an accuracy of 1.7 σ. The chemical composition of this model suggests a decrease…
The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud with Hubble Space Telescope ACS Observations
Henning, Thomas; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +1 more
We present our photometric study of the stellar association NGC 602 in the wing of the Small Magellanic Cloud (SMC). The data were taken in the filters F555W and F814W using the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). Photometry was performed using the ACS module of the stellar photometry package DOLPHOT. We de…
Simultaneous Estimation of Time Delays and Quasar Structure
Kochanek, C. S.; Morgan, Nicholas D.; Meylan, G. +5 more
We expand our Bayesian Monte Carlo method for analyzing the light curves of gravitationally lensed quasars to simultaneously estimate time delays and the sizes of quasar continuum emission regions including their mutual uncertainties. We apply the method to HE1104-1805 and QJ0158-4325, two doubly imaged quasars with microlensing and intrinsic vari…
On the White Dwarf Cooling Sequence of the Globular Cluster ω Centauri
Degl'Innocenti, S.; Marchetti, E.; Pulone, L. +16 more
We present deep and precise photometry (F435W, F625W, F658N) of ω Cen collected with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). We have identified ≈6500 white dwarf (WD) candidates, and the ratio of WD to main-sequence (MS) star counts is found to be at least a factor of 2 larger than the ratio of CO-core WD c…
Determination of Magnetic Diffusivity from High-Resolution Solar Magnetograms
Chae, Jongchul; Litvinenko, Yuri E.; Sakurai, Takashi
The magnetic diffusivity in the solar photosphere is determined by applying a new method to the magnetic induction equation. The magnetic field evolution is specified by a time sequence of high-resolution magnetograms of plage regions, taken by Hinode/SOT and SOHO/MDI. The mean value of magnetic diffusivity determined from SOT magnetograms with th…
The Optical Spectra of 24 µm Galaxies in the COSMOS Field. I. Spitzer MIPS Bright Sources in the zCOSMOS-Bright 10k Catalog
Kneib, J. -P.; Maccagni, D.; Aussel, H. +62 more
We study zCOSMOS-bright optical spectra for 609 Spitzer MIPS 24 µm-selected galaxies with S24 µ m > 0.30 mJy and I < 22.5 (AB mag) over 1.5 deg2 of the COSMOS field. From emission-line diagnostics we find the following: (1) SFRs derived from the observed Hα λ6563 and Hβ λ4861 lines underestimate, on average,…
A Puzzling Millisecond Pulsar Companion in NGC 6266
Possenti, A.; Beccari, G.; D'Amico, N. +5 more
We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701-3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red color and an optical variability (~0.2 mag) that nicely correlates with the orbital period of the pulsar (~0.144 days) has been found nearly coincident with th…
Forming Early-Type Galaxies in Groups Prior to Cluster Assembly
Tran, Kim-Vy H.; Moustakas, John; Gonzalez, Anthony H. +3 more
We study a unique protocluster of galaxies, the supergroup SG1120-1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z = 0. SG1120-1202 at z ~ 0.37 is composed of four gravitationally bound groups that ar…