Search Publications
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…
Interpreting the Properties of Solar Energetic Particle Events by Using Combined Imaging and Modeling of Interplanetary Shocks
St. Cyr, O. C.; Szabo, A.; Rouillard, A. P. +10 more
Images of the solar corona obtained by the Solar-Terrestrial Relations Observatory (STEREO) provide high-cadence, high-resolution observations of a compression wave forming ahead of a fast (940 km s-1) coronal mass ejection (CME) that erupted at ~9:00 UT on 2010 April 03. The passage of this wave at 1 AU is detected in situ by the Advan…
AEGIS: The Morphologies of Green Galaxies at 0.4 < z < 1.2
Moustakas, John; Salim, Samir; Coil, Alison L. +3 more
We present quantitative morphologies of ~300 galaxies in the optically defined green valley at 0.4 < z < 1.2, in order to constrain the mechanism(s) responsible for quenching star formation in the bulk of this population. The sample is selected from galaxies in the All-Wavelength Extended Groth Strip International Survey (AEGIS). While the g…
Are C60 Molecules Detectable in Circumstellar Shells of R Coronae Borealis Stars?
Lambert, D. L.; García-Hernández, D. A.; Kameswara Rao, N.
The hydrogen-poor, helium-rich, and carbon-rich character of the gas around R Coronae Borealis (RCB) stars has been suggested to be a site for formation of C60 molecules. This suggestion is not supported by observations reported here showing that infrared transitions of C60 are not seen in a large sample of RCB stars observed…
Supermassive Black Hole Growth in Starburst Galaxies over Cosmic Time: Constraints from the Deepest Chandra Fields
Lehmer, B. D.; Alexander, D. M.; Papovich, C. +5 more
We present an analysis of deep multiwavelength data for z ≈ 0.3-3 starburst galaxies selected by their 70 µm emission in the Extended-Chandra Deep Field-South and Extended Groth Strip. We identify active galactic nuclei (AGNs) in these infrared sources through their X-ray emission and quantify the fraction that host an AGN. We find that the …
Evidence for an FU Orionis-like Outburst from a Classical T Tauri Star
Filippenko, Alexei V.; Cenko, S. Bradley; Law, Nicholas M. +28 more
We present pre- and post-outburst observations of the new FU Orionis-like young stellar object PTF 10qpf (also known as LkHα 188-G4 and HBC 722). Prior to this outburst, LkHα 188-G4 was classified as a classical T Tauri star (CTTS) on the basis of its optical emission-line spectrum superposed on a K8-type photosphere and its photometric variabilit…