Search Publications
Correlated X-ray/ultraviolet/optical variability in the very low mass AGN NGC 4395
McHardy, I.; Breedt, E.; Uttley, P. +4 more
We report the results of a 1-yr Swift X-ray/ultraviolet (UV)/optical programme monitoring the dwarf Seyfert nucleus in NGC 4395 in 2008-2009. The UV/optical flux from the nucleus was found to vary dramatically over the monitoring period, with a similar pattern of variation in each of the observed UV/optical bands (spanning 1900-5500 Å). In particu…
Of "Cocktail Parties" and Exoplanets
Waldmann, I. P.
The characterization of ever smaller and fainter extrasolar planets requires an intricate understanding of one's data and the analysis techniques used. Correcting the raw data at the 10-4 level of accuracy in flux is one of the central challenges. This can be difficult for instruments that do not feature a calibration plan for such high…
The Hubble Space Telescope Cluster Supernova Survey. III. Correlated Properties of Type Ia Supernovae and Their Hosts at 0.9 < Z < 1.46
Gladders, M. D.; Lidman, C.; Rubin, D. +36 more
Using the sample of Type Ia supernovae (SNe Ia) discovered by the Hubble Space Telescope (HST) Cluster Supernova Survey and augmented with HST-observed SNe Ia in the Great Observatories Origins Deep Survey (GOODS) fields, we search for correlations between the properties of SNe and their host galaxies at high redshift. We use galaxy color and quan…
Enceladus: A hypothesis for bringing both heat and chemicals to the surface
Matson, Dennis L.; Johnson, Torrence V.; Castillo-Rogez, Julie C. +1 more
The eruptive plumes and large heat flow (∼15 GW) observed by Cassini in the South Polar Region of Enceladus may be expressions of hydrothermal activity inside Enceladus. We hypothesize that a subsurface ocean is the heat reservoir for thermal anomalies on the surface and the source of heat and chemicals necessary for the plumes. The ocean is belie…
Empirical energy spectra of neutralized solar wind protons from the lunar regolith
Barabash, S.; Holmström, M.; Futaana, Y. +7 more
We present an empirical model of the energy spectra for hydrogen energetic neutral atoms (ENA) backscattered from the lunar surface based on Chandrayaan-1 Energetic Neutral Atom (CENA) observations. The observed energy spectra of the backscattered ENAs are well reproduced by Maxwell-Boltzmann distribution functions. The backscatter fraction is con…
The Connection between Internetwork Magnetic Elements and Supergranular Flows
Bellot Rubio, L. R.; Katsukawa, Y.; Orozco Suárez, D.
The advection of internetwork magnetic elements by supergranular convective flows is investigated using high spatial resolution, high cadence, and high signal-to-noise ratio Na I D1 magnetograms obtained with the Hinode satellite. The observations show that magnetic elements appear everywhere across the quiet Sun surface. We calculate the proper m…
EUV SpectroPhotometer (ESP) in Extreme Ultraviolet Variability Experiment (EVE): Algorithms and Calibrations
Didkovsky, L.; Jones, A.; Judge, D. +2 more
The Extreme ultraviolet SpectroPhotometer (ESP) is one of five channels of the Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO). The ESP channel design is based on a highly stable diffraction transmission grating and is an advanced version of the Solar Extreme ultraviolet Monitor (SEM), which has b…
Narrow Dust Jets in a Diffuse Gas Coma: A Natural Product of Small Active Regions on Comets
Combi, M. R.; Fougere, N.; Gombosi, T. I. +2 more
Comets often display narrow dust jets but more diffuse gas comae when their eccentric orbits bring them into the inner solar system and sunlight sublimates the ice on the nucleus. Comets are also understood to have one or more active areas covering only a fraction of the total surface active with sublimating volatile ices. Calculations of the gas …
X-Ray Observations of the New Unusual Magnetar Swift J1834.9-0846
Pavlov, George G.; Kargaltsev, Oleg; Griffith, Roger L. +6 more
We present X-ray observations of the new transient magnetar Swift J1834.9-0846, discovered with the Swift Burst Alert Telescope on 2011 August 7. The data were obtained with Swift, Rossi X-ray Timing Explorer (RXTE), CXO, and XMM-Newton both before and after the outburst. Timing analysis reveals single peak pulsations with a period of 2.4823 s and…
Transiting exoplanets from the CoRoT space mission. XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet
Mazeh, T.; Aigrain, S.; Alonso, R. +43 more
We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 ± 0.23 MJup and a radius of 0.84 ± 0.04 RJup. With a mean density of 8.87 ± 1.10 g cm-3, it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy el…