Search Publications
HD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT
Auvergne, M.; Baudin, F.; Michel, E. +12 more
Accurate photometric CoRoT space observations of a secondary seismological target, HD 174884, led to the discovery that this star is an astrophysically important double-lined eclipsing spectroscopic binary in an eccentric orbit (e∼0.3), unusual for its short 3.65705° orbital period. The high eccentricity, coupled with the orientation of the binary…
Infrared Spectrograph Spectroscopy and Multi-Wavelength Study of Luminous Star-Forming Galaxies at z ≃ 1.9
Smail, I.; Daddi, E.; Le Floc'h, E. +24 more
We analyze a sample of galaxies chosen to have F 24 µm > 0.5 mJy and satisfy a certain IRAC color criterion. Infrared Spectrograph (IRS) spectra yield redshifts, spectral types, and polycyclic aromatic hydrocarbons (PAH) luminosities, to which we add broadband photometry from optical through IRAC wavelengths, MIPS from 24-160 &…
z ~ 7-10 Galaxies Behind Lensing Clusters: Contrast with Field Search Results
Broadhurst, Tom; Franx, Marijn; Illingworth, Garth D. +6 more
We conduct a search for z gsim 7 dropout galaxies behind 11 massive lensing clusters using 21 arcmin2 of deep Hubble Space Telescope NICMOS, ACS, and WFPC2 image data. In total, over this entire area, we find only one robust z ~ 7 z-dropout candidate (previously reported around Abell 1689). Four less robust z-dropout and J-dropout candi…
The Physics of Crystallization From Globular Cluster White Dwarf Stars in NGC 6397
Kepler, S. O.; Montgomery, M. H.; Winget, D. E. +4 more
We explore the physics of crystallization in the deep interiors of white dwarf (WD) stars using the color-magnitude diagram and luminosity function constructed from proper-motion cleaned Hubble Space Telescope photometry of the globular cluster NGC 6397. We demonstrate that the data are consistent with the theory of crystallization of the ions in …
Comparing GC and Field LMXBs in Elliptical Galaxies with Deep Chandra and Hubble Data
Zezas, A.; Gallagher, J. S.; King, A. R. +15 more
We present a statistical study of the low-mass X-ray binary (LMXB) populations of three nearby, old elliptical galaxies: NGC 3379, NGC 4278, and NGC 4697. With a cumulative ~1 Ms Chandra ACIS observing time, we detect 90-170 LMXBs within the D25 ellipse of each galaxy. Cross-correlating Chandra X-ray sources and HST optical sources, we …
Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration
Bouret, J. -C.; Wade, G. A.; Neiner, C. +10 more
We report the detection of a strong, organized magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Programme. From the fitting of our spectra using non-local thermodynamic equilibrium mo…
Lineated valley fill (LVF) and lobate debris aprons (LDA) in the Deuteronilus Mensae northern dichotomy boundary region, Mars: Constraints on the extent, age and episodicity of Amazonian glacial events
Head, James W.; Marchant, David R.; Morgan, Gareth A.
In order to assess the nature, degradational processes and history of the dichotomy boundary on Mars, we conducted a detailed morphological analysis of a 70,000 km2 region of its northern portion (north-central Deuteronilus Mensae, south of Lyot, in the vicinity of Sinton Crater). This region is characterized by the distinctive sinuous …
The Optical Structure of the Starburst Galaxy M82. I. Dynamics of the Disk and Inner-Wind
Bastian, N.; Smith, L. J.; Gallagher, J. S., III +3 more
We present Gemini-North GMOS-IFU observations of the central starburst clumps and inner wind of M82, together with WIYN DensePak IFU observations of the inner 2 × 0.9 kpc of the disk. These cover the emission lines of Hα, [N II], [S II], and [S III] at a spectral resolution of 45-80 km s-1. The high signal-to-noise of the data is suffic…
A Photoionized Nebula Surrounding and Variable Optical Continuum Emission from the Ultraluminous X-Ray Source in NGC 5408
Kaaret, Philip; Corbel, Stéphane
We obtained optical spectra of the counterpart of the ultraluminous X-ray source NGC 5408 X-1 using the FORS spectrograph on the Very Large Telescope. The spectra show strong high-excitation emission lines, He II λ4686 and [Ne V] λ3426, indicative of X-ray photoionization. Using the measured X-ray spectrum as input to a photoionization model, we c…
The chemical abundance analysis of normal early A- and late B-type stars
Ryabchikova, T.; Fossati, L.; Alecian, E. +4 more
Context: Modern spectroscopy of early-type stars often aims at studying complex physical phenomena such as stellar pulsation, the peculiarity of the composition of the photosphere, chemical stratification, the presence of a magnetic field, and its interplay with the stellar atmosphere and the circumstellar environment. Comparatively less attention…