Search Publications
Constraining the Fundamental Parameters of the O-Type Binary CPD -41 7733
Gosset, E.; Rauw, G.; Sana, H.
Using a set of high-resolution spectra, we studied the physical and orbital properties of the O-type binary CPD -41 7733, located in the core of NGC 6231. We report the unambiguous detection of a secondary spectral signature and we derive the first SB2 orbital solution of the system. The period is 5.6815+/-0.0015 days, and the orbit has no signifi…
Solar Cycle Variation of Real CME Latitudes
Feng, Xueshang; Song, Wenbin; Hu, Yanqi
With the assumption of radial motion and uniform longitudinal distribution of coronal mass ejections (CMEs), we propose a method to eliminate projection effects from the apparent observed CME latitude distribution. This method has been applied to SOHO LASCO data from 1996 January to 2006 December. As a result, we find that the real CME latitude di…
Super Star Cluster NGC 1705-1: A Local Analog to the Birth Site of Long-Duration γ-Ray Bursts
Chen, Hsiao-Wen; Bloom, Joshua S.; Prochaska, Jason X.
Recent observations suggest that global properties of the host galaxies for long-duration γ-ray bursts (GRBs) are particularly well suited for creating the massive star progenitors of these GRBs. Motivated by the hypothesis that massive young star clusters located in metal-poor, low-metallicity galaxies are a natural birth site for GRB progenitors…
Damp Mergers: Recent Gaseous Mergers without Significant Globular Cluster Formation?
Forbes, Duncan A.; Brodie, Jean P.; Strader, Jay +1 more
Here we test the idea that new globular clusters (GCs) are formed in the same gaseous (``wet'') mergers or interactions that give rise to the young stellar populations seen in the central regions of many early-type galaxies. We compare mean GC colors with the age of the central galaxy starburst. The red GC subpopulation reveals remarkably constant…
Far-Infrared Detection of H2D+ toward Sgr B2
Cernicharo, J.; Goicoechea, J. R.; Polehampton, E.
We report on the first far-IR detection of H2D+, using the Infrared Space Observatory, in the line of sight toward Sgr B2 in the Galactic center. The transition at λ=126.853 µm connecting the ground level of o-H2D+, 11,1, with the 21,2 level at 113 K is observed in absorption …
Modeling Minor Ion Abundances in Quiescent Coronal Loops
Lie-Svendsen, Øystein; Killie, Mari Anne
We model minor element abundances in quiescent coronal loops anchored in the chromosphere, solving transport equations that give an improved description of thermal forces. Ionization, recombination, and radiative loss are included. The plasma consists of hydrogen and a minor element (oxygen, silicon, or iron), and we solve for all relevant charge …
Low Star Formation Rates for z = 1 Early-Type Galaxies in the Very Deep GOODS MIPS Imaging: Implications for Their Optical/Near-Infrared Spectral Energy Distributions
van der Wel, A.; Illingworth, G. D.; Franx, M. +1 more
We measure the obscured star formation in z~1 early-type galaxies. This constrains the influence of star formation on their optical/near-IR colors, which, we found, are redder than predicted by the model by Bruzual & Charlot. From deep ACS imaging we construct a sample of 95 morphologically selected early-type galaxies in the HDF-N and CDF-S w…
Does High Plasma-β Dynamics ``Load'' Active Regions?
McIntosh, Scott W.
Using long-duration observations in the He II 304 Å passband of SOHO EIT, we investigate the spatial and temporal appearance of impulsive intensity fluctuations in the pixel light curves. These passband intensity fluctuations come from plasma emitting in the chromosphere, in the transition region, and in the lowest portions of the corona. We see t…
Modeling the Accretion Disk X-Ray Continuum of Black Hole Candidates
Cui, Wei; Pszota, Gabor
We critically examine issues associated with determining the fundamental properties of the black hole and the surrounding accretion disk in an X-ray binary based on modeling the disk X-ray continuum of the source. We base our work mainly on two XMM-Newton observations of GX 339-4, because they provided high-quality data at low energies (below 1 ke…
Anticorrelation between Moving Magnetic Features and Coronal Loop Formation
Title, A.; Ryutova, M. P.; Hagenaar, H.
We study a possible connection of moving magnetic features (MMFs) and the overlying atmosphere using several sets of multiwavelength observations of sunspot areas from the photosphere to the corona. We find that as a collective phenomenon, very intense MMF formation anticorrelates with the presence of large-scale ``stable'' coronal loops: such loo…