Search Publications
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 …
Orbital Motion of HR 8799 b, c, d Using Hubble Space Telescope Data from 1998: Constraints on Inclination, Eccentricity, and Stability
Pueyo, Laurent; Marois, Christian; Rajan, Abhijith +3 more
HR 8799 is currently the only multiple-planet system that has been detected with direct imaging, with four giant planets of masses 7-10 M Jup orbiting at large separations (15-68 AU) from this young late A star. Orbital motion provides insight into the stability and possible formation mechanisms of this planetary system. Dynamical studi…
The Stellar Velocity Dispersion of a Compact Massive Galaxy at z = 1.80 Using X-Shooter: Confirmation of the Evolution in the Mass-Size and Mass-Dispersion Relations
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +7 more
Recent photometric studies have shown that early-type galaxies at fixed stellar mass were smaller and denser at earlier times. In this Letter, we assess that finding by deriving the dynamical mass of such a compact quiescent galaxy at z = 1.8. We have obtained a high-quality spectrum with full UV-NIR wavelength coverage of galaxy NMBS-C7447 using …
Star Formation in 30 Doradus
Mutchler, Max; McCarthy, Patrick J.; Calzetti, Daniela +24 more
Using observations obtained with the Wide-Field Camera 3 on board the Hubble Space Telescope, we have studied the properties of the stellar populations in the central regions of 30 Dor in the Large Magellanic Cloud. The observations clearly reveal the presence of considerable differential extinction across the field. We characterize and quantify t…
The End of Helium Reionization at z ~= 2.7 Inferred from Cosmic Variance in HST/COS He II Lyα Absorption Spectra
Richter, Philipp; Hennawi, Joseph F.; Worseck, Gábor +6 more
We report on the detection of strongly varying intergalactic He II absorption in HST/COS spectra of two z em ~= 3 quasars. From our homogeneous analysis of the He II absorption in these and three archival sightlines, we find a marked increase in the mean He II effective optical depth from < τ_{eff,He II}> ≃ 1 at z ~= 2.3 to < τ…
Hubble Space Telescope Observations of Main-belt Comet (596) Scheila
Mutchler, Max; Jewitt, David; Agarwal, Jessica +2 more
We present Hubble Space Telescope Observations of (596) Scheila during its recent dust outburst. The nucleus remained point-like with absolute magnitude HV = 8.85 ± 0.02 in our data, equal to the pre-outburst value, with no secondary fragments of diameter >=100 m (for assumed albedos 0.04). We find a coma having a peak scattering cro…