Search Publications
Estimating Stellar Rotation from Starspot Detection during Planetary Transits
Silva-Valio, Adriana
A new method for determining the stellar rotation period is proposed here, based on the detection of starspots during transits of an extrasolar planet orbiting its host star. As the planet eclipses the star, it may pass in front of a starspot which will then make itself known through small flux variations in the transit light curve. If we are luck…
Morphologies and Color Gradients of Luminous Evolved Galaxies at z ~ 1.5
McGrath, Elizabeth J.; Stockton, Alan; Canalizo, Gabriela +2 more
We have examined in detail the morphologies of seven z ~ 1.5 passively evolving luminous red galaxies using high-resolution HST NICMOS and ACS imaging data. Almost all of these galaxies appear to be relaxed systems, with smooth morphologies at both rest-frame UV and visible wavelengths. Previous results from spectral synthesis modeling favor a sin…
Wavelet Analysis of AGN X-Ray Time Series: A QPO in 3C 273?
Bregman, J.; Espaillat, C.; Hughes, P. +1 more
Quasi-periodic signals have yielded important constraints on the masses of black holes in galactic X-ray binaries, and here we extend this to active galactic nuclei (AGNs). We employ a wavelet technique to analyze 19 observations of 10 AGNs obtained with the XMM-Newton EPIC pn camera. We report the detection of a candidate 3.3 ks quasi period in 3…
Coronal Mass Ejection-Associated Coronal Dimmings
Biesecker, D. A.; Reinard, A. A.
We report on a statistical analysis of 96 CME-associated EUV coronal dimmings between 1998 and 2000. We investigate the size and location of the events and characterize how these events evolve with time. The durations typically range from 3 to 12 hr. The dimmings appear most frequently within the belt of active regions (20°-50° latitude). Dimming …
Infrared and X-Ray Evidence for Circumstellar Grain Destruction by the Blast Wave of Supernova 1987A
Polomski, Elisha F.; Gehrz, Robert D.; Woodward, Charles E. +10 more
Multiwavelength observations of supernova remnant 1987A show that its morphology and luminosity are rapidly changing at X-ray, optical, infrared (IR), and radio wavelengths as the blast wave from the explosion expands into the circumstellar equatorial ring, produced by mass loss from the progenitor star. The observed IR radiation arises from the i…
The Burst Spectra of EXO 0748-676 during a Long 2003 XMM-Newton Observation
Boirin, L.; Miller, J. M.; Lewin, W. H. G. +4 more
Gravitationally redshifted absorption lines from highly ionized iron have been previously identified in the burst spectra of the neutron star in EXO 0748-676. To repeat this detection we obtained a long, nearly 600 ks observation of the source with XMM-Newton in 2003. The spectral features seen in the burst spectra from the initial data are not re…
Spectral, Spatial, and Time Properties of the Hydrogen Nebula around Exoplanet HD 209458b
Ben-Jaffel, Lotfi
All far-ultraviolet (FUV) observations of HD 209458 tend to support a scenario in which the inflated hydrogen atmosphere of its planetary companion strongly absorbs the stellar Lyα flux during transit. However, it is not clear how the transit absorption depends on the selected wavelength range in the stellar line profile, nor how the atomic hydrog…
A STIS Survey for O VI Absorption Systems at 0.12 < z lesssim 0.5. I. The Statistical Properties of Ionized Gas
Chen, Hsiao-Wen; Thom, C.
We have conducted a systematic survey for intervening O VI absorbers in available echelle spectra of 16 QSOs at zQSO = 0.17-0.57. These spectra were obtained using HST STIS with the E140M grating. Our search uncovered a total of 27 foreground O VI absorbers with rest-frame absorption equivalent width Wr(1031) gtrsim 25 mÅ. Te…
Star Formation Rates in Lyman Break Galaxies: Radio Stacking of LBGs in the COSMOS Field and the Sub-µJy Radio Source Population
Smolčić, V.; Taniguchi, Y.; Yun, M. S. +10 more
We present an analysis of the radio properties of large samples of Lyman break galaxies (LBGs) at z ~ 3, 4, and 5 from the COSMOS field. The median stacking analysis yields a statistical detection of the z ~ 3 LBGs (U-band dropouts), with a 1.4 GHz flux density of 0.90 +/- 0.21 µJy. The stacked emission is unresolved, with a size <1, or a…
The Stellar Content of Galaxy Halos: A Comparison between ΛCDM Models and Observations of M31
Robertson, Brant E.; Tumlinson, Jason; Johnston, Kathryn V. +4 more
Recent observations have revealed that high surface brightness, metal-rich debris is present over large regions of the Andromeda (M31) stellar halo. We use a set of numerical models to determine whether extended metal-rich debris is expected to exist in galaxy halos formed in a hierarchical ΛCDM universe. We identify tidal debris in the simulation…