Search Publications
Spiraling Out of Control: Three-dimensional Hydrodynamical Modeling of the Colliding Winds in η Carinae
Corcoran, M. F.; Hamaguchi, K.; Pittard, J. M. +1 more
Three-dimensional adaptive mesh refinement hydrodynamical simulations of the wind-wind collision between the enigmatic supermassive star η Car and its mysterious companion star are presented which include radiative driving of the stellar winds, gravity, optically thin radiative cooling, and orbital motion. Simulations with static stars with a peri…
Quantitative evidence of an intrinsic luminosity spread in the Orion nebula cluster
Robberto, M.; Da Rio, N.; Ricci, L. +3 more
Aims: We study the distribution of stellar ages in the Orion nebula cluster (ONC) using accurate HST photometry taken from HST Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the s…
Atmospheric Imaging Assembly Observations of Hot Flare Plasma
Reeves, Katharine K.; Golub, Leon
We present observations of hot plasma from solar eruptions recorded by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. AIA is the first narrowband instrument capable of taking images of hot plasma in the 5-15 MK range. We find that there are hot structures above flare loops, and that they are typically more diffuse and ne…
EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
Magain, P.; Villanueva, G. L.; Reach, W. T. +194 more
Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small a…
Early magnetic B-type stars: X-ray emission and wind properties
Hamann, W. -R.; Oskinova, L. M.; Ignace, R. +3 more
We present a comprehensive study of X-ray emission by, and wind properties of, massive magnetic early B-type stars. Dedicated XMM-Newton observations were obtained for three early-type B-type stars, ξ1 CMa, V2052 Oph and ζ Cas, with recently discovered magnetic fields. We report the first detection of X-ray emission from V2052 Oph and ζ…
Challenging times: a re-analysis of NGC 5408 X-1
Done, C.; Roberts, T. P.; Middleton, M. J. +1 more
The ultraluminous X-ray source, NGC 5408 X-1, is one of only three such objects to show a quasi-periodic oscillation (QPO) in its power spectrum. Previous analysis of this signal identified it with the well-studied type-C low-frequency QPO (LFQPO) seen in black hole binaries (BHBs), implying an intermediate mass black hole (IMBH). However, in BHBs…
The Cool Accretion Disk in ESO 243-49 HLX-1: Further Evidence of an Intermediate-mass Black Hole
Davis, Shane W.; Narayan, Ramesh; Godet, Olivier +5 more
With an inferred bolometric luminosity exceeding 1042 erg s-1, HLX-1 in ESO 243-49 is the most luminous of ultraluminous X-ray sources and provides one of the strongest cases for the existence of intermediate-mass black holes. We obtain good fits to disk-dominated observations of the source with BHSPEC, a fully relativistic b…
Observations of Binary Stars with the Differential Speckle Survey Instrument. II. Hipparcos Stars Observed in 2010 January and June
Howell, Steve B.; Ciardi, David R.; Horch, Elliott P. +4 more
The results of 497 speckle observations of Hipparcos stars and selected other targets are presented. Of these, 367 were resolved into components and 130 were unresolved. The data were obtained using the Differential Speckle Survey Instrument at the WIYN 3.5 m Telescope. (The WIYN Observatory is a joint facility of the University of Wisconsin-Madis…
Compact Optical Counterparts of Ultraluminous X-Ray Sources
Tao, Lian; Feng, Hua; Grisé, Fabien +1 more
Using archival Hubble Space Telescope (HST) imaging data, we report the multiband photometric properties of 13 ultraluminous X-ray sources (ULXs) that have a unique compact optical counterpart. Both magnitude and color variation are detected at timescales of days to years. The optical color, variability, and X-ray to optical flux ratio indicate th…
Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150, and HD 46966
Auvergne, M.; Gosset, E.; Baudin, F. +15 more
Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars.
Aims: We analyse the CoRoT data corresponding to three hot O-ty…