Search Publications
Discovery of the progenitor of the type Ia supernova 2007on
Nelemans, Gijs; Voss, Rasmus
Type Ia supernovae are exploding stars that are used to measure the accelerated expansion of the Universe and are responsible for most of the iron ever produced. Although there is general agreement that the exploding star is a white dwarf in a binary system, the exact configuration and trigger of the explosion is unclear, which could hamper their …
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…
Observations of aurorae by SPICAM ultraviolet spectrograph on board Mars Express: Simultaneous ASPERA-3 and MARSIS measurements
Lundin, R.; Futaana, Y.; Winningham, J. D. +12 more
We present a new set of observations of Martian aurorae obtained by Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express (MEX). Using nadir viewing, several auroral events have been identified on the Martian nightside, all near regions of crustal magnetic fields. For most of these event…
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…
AKARI/IRC Deep Survey in the North Ecliptic Pole Region
Goto, Tomotsugu; Oyabu, Shinki; Ohyama, Youichi +10 more
We have made adeep and wide imaging survey with all nine AKARI/IRC bands from 2 to 24 µm within ahalf degree of the North Ecliptic Pole. The survey covered acircular area of 0.38deg2 centered at RA = 17h56m, Dec = 66°37' where adeep optical multi-band survey has been conducted by Subaru/Suprime-Cam. The 5σ se…
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 …
Spectral morphology of the X-ray emission from Jupiter's aurorae
Branduardi-Raymont, G.; Galand, M.; Waite, J. H. +5 more
Simultaneous Chandra X-ray and Hubble Space Telescope FUV observations of Jupiter's aurorae carried out in February 2003 have been re-examined to investigate the spatial morphology of the X-ray events in different energy bands. The data clearly show that in the Northern auroral region (in the main auroral oval and the polar cap) events with energy…
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…
Deep Advanced Camera for Surveys Imaging in the Globular Cluster NGC 6397: Reduction Methods
Anderson, Jay; Rich, R. Michael; Stetson, Peter B. +6 more
We describe here the reduction methods that we developed to study the faintest red dwarfs and white dwarfs in an outer field of NGC 6397, which was observed by HST for 126 orbits in 2005. The particular challenge of this data set is that the faintest stars are not readily visible in individual exposures, so special care must be taken to combine th…