Search Publications
Pulsed Gamma Rays from the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope
Caraveo, P. A.; Frailis, M.; Orlando, E. +169 more
We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP to be detected in gamma rays after PSR J0218+4232, observed by the EGRET instrument on the Compton…
The X17.2 flare occurred in NOAA 10486: an example of filament destabilization caused by a domino effect
Guglielmino, S. L.; Romano, P.; Contarino, L. +6 more
Context: It is now possible to distinguish between two main models describing the mechanisms responsible for eruptive flares : the standard model, which assumes that most of the energy is released, by magnetic reconnection, in the region hosting the core of a sheared magnetic field, and the breakout model, which assumes reconnection occurs at firs…
Helium-core White Dwarfs in the Globular Cluster NGC 6397
Anderson, Jay; Cool, Adrienne M.; Serenelli, Aldo M. +3 more
We present results of a study of the central regions of NGC 6397 using Hubble Space Telescope's Advanced Camera for Surveys (HST ACS), focusing on a group of 24 faint blue stars that form a sequence parallel to, but brighter than, the more populated sequence of carbon-oxygen white dwarfs (CO WDs). Using F625W, F435W, and F658N filters with the Wid…
The radial width of a Coronal Mass Ejection between 0.1 and 0.4 AU estimated from the Heliospheric Imager on STEREO
Harrison, R. A.; Davies, J. A.; Owens, M. J. +4 more
On 15-17 February 2008, a CME with an approximately circular cross section was tracked through successive images obtained by the Heliospheric Imager (HI) instrument onboard the STEREO-A spacecraft. Reasoning that an idealised flux rope is cylindrical in shape with a circular cross-section, best fit circles are used to determine the radial width of…
Properties of the nuclei and comae of 13 ecliptic comets from Hubble Space Telescope snapshot observations
Jorda, L.; Lamy, P. L.; A'Hearn, M. F. +2 more
Context: Knowledge of the size distribution of cometary nuclei and, more generally, of their physical properties is important for constraining models of the formation and evolution of the Solar System.
Aims: We report on our on-going effort to determine the ensemble properties of comets based on our success in detecting the nuclei of active c…
The enigmatic X-rays from the Herbig star HD 163296: Jet, accretion, or corona?
Schmitt, J. H. M. M.; Günther, H. M.
Context: Herbig Ae/Be stars (HAeBe) are pre-main sequence objects in the mass range 2 M⊙ < M* < 8 M⊙. Their X-ray properties are uncertain and, as yet, unexplained.
Aims: We want to elucidate the X-ray generating mechanism in HAeBes.
Methods: We present an XMM-Newton observation of the HAeBe HD 163296…
The Compton-thick AGN in the Chandra Deep Field North
Georgakakis, A.; Georgantopoulos, I.; Rowan-Robinson, M. +1 more
We present X-ray spectral analysis of the brightest sources (f2{-10 keV} > 10-15 erg cm-2 s-1) in the Chandra Deep Field North. Our sample consists of 222 sources; for the vast majority (171) either a spectroscopic or a photometric redshift is available. Our goal is to discover the Compton-thick AGN i…
Observational Evidence on the Presence of an Outer Reflecting Boundary in Solar Energetic Particle Events
Wang, Linghua; Reames, Donald V.; Tan, Lun C. +2 more
We have focused primarily on the 2001 September 24 solar energetic particle (SEP) event to verify previous indications of the presence of an outer reflecting boundary of SEPs. By using energetic electron and ion data obtained from multi-spacecraft observations, we have identified a collimated particle beam consisting of reflected particles returni…
Spitzer Observations of Comet 67P/Churyumov-Gerasimenko at 5.5-4.3 AU from the Sun
Woodward, Charles E.; Tubiana, Cecilia; Kelley, Michael S. +3 more
We report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will rendezvous with the nucleus at heliocentric distances similar to our observations. Rotationally resolved observa…
Observational Constraints on the Co-Evolution of Supermassive Black Holes and Galaxies
Jahnke, K.; Meisenheimer, K.; Rix, H. -W. +6 more
The star formation rate (SFR) and black hole accretion rate (BHAR) functions are measured to be proportional to each other at z lsim 3. This close correspondence between SF and BHA would naturally yield a BH mass-galaxy mass correlation, whereas a BH mass-bulge mass correlation is observed. To explore this apparent contradiction, we study the SF i…