Search Publications
Emission Lines from the Gas Disk around TW Hydra and the Origin of the Inner Hole
Pascucci, I.; Najita, J.; Hollenbach, D. +1 more
We compare line emission calculated from theoretical disk models with optical to submillimeter wavelength observational data of the gas disk surrounding TW Hya and infer the spatial distribution of mass in the gas disk. The model disk that best matches observations has a gas mass ranging from ~10-4 to 10-5 M sun fo…
Fe-K Line Probing of Material Around the Active Galactic Nucleus Central Engine with Suzaku
Fukazawa, Yasushi; Ohno, Masanori; Nishino, Sho +6 more
We systematically analyzed the high-quality Suzaku data of 88 Seyfert galaxies, about 31% of which are Compton-thick active galactic nuclei (AGNs). We obtained a clear relation between the absorption column density and the equivalent width (EW) of the 6.4 keV line above 1023 cm-2, suggesting a wide-ranging column density of 1…
Evidence for Cold Accretion: Primitive Gas Flowing onto a Galaxy at z ~ 0.274
Tripp, Todd M.; Prochaska, J. Xavier; Lehner, Nicolas +5 more
We present UV and optical observations from the Cosmic Origins Spectrograph on the Hubble Space Telescope and Keck of a z = 0.27395 Lyman limit system (LLS) seen in absorption against the QSO PG1630+377. We detect H I absorption with log N(H I) = 17.06 ± 0.05 as well as Mg II, C III, Si III, and O VI in this system. The column densities are readil…
XRF 100316D/SN 2010bh and the Nature of Gamma-Ray Burst Supernovae
D'Avanzo, P.; Melandri, A.; Pian, E. +21 more
We present ground-based and Hubble Space Telescope optical and infrared observations of Swift XRF 100316D/SN 2010bh. It is seen that the optical light curves of SN 2010bh evolve at a faster rate than the archetype gamma-ray burst supernova (GRB-SN) 1998bw, but at a similar rate to SN 2006aj, an SN that was spectroscopically linked with XRF 060218,…
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…
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…
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…
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…
Very Large Telescope/NACO Polarimetric Differential Imaging of HD100546—Disk Structure and Dust Grain Properties between 10 and 140 AU
Henning, Thomas; Brandner, Wolfgang; Meyer, Michael R. +4 more
We present polarimetric differential imaging (PDI) data of the circumstellar disk around the Herbig Ae/Be star HD100546 obtained with Very Large Telescope/NACO. We resolve the disk in polarized light in the H and Ks filter between ~0farcs1 and 1farcs4 (i.e., ~10-140 AU). The innermost disk regions are directly imaged for the first time …