Search Publications
Is Active Region Core Variability Age Dependent?
Warren, Harry P.; Ugarte-Urra, Ignacio
The presence of both steady and transient loops in active region cores has been reported from soft X-ray and extreme-ultraviolet observations of the solar corona. The relationship between the different loop populations, however, remains an open question. We present an investigation of the short-term variability of loops in the core of two active r…
Discovery of an Active Supermassive Black Hole in the Bulgeless Galaxy NGC 4561
Ferrarese, L.; Fiore, F.; Mathur, S. +2 more
We present XMM-Newton observations of the Chandra-detected nuclear X-ray source in NGC 4561. The hard X-ray spectrum can be described by a model composed of an absorbed power law with Γ = 2.5+0.4 - 0.3 and column density NH = 1.9+0.1 - 0.2 × 1022 atoms cm-2. The absorptio…
On the Nature of the Progenitor of the Type Ia SN2011fe in M101
Liu, Jifeng; Wang, Tao; Di Stefano, Rosanne +1 more
The explosion of a Type Ia supernova, SN2011fe, in the nearby Pinwheel galaxy (M101 at 6.4 Mpc) provides an opportunity to study pre-explosion images and search for the progenitor, which should consist of a white dwarf (WD), possibly surrounded by an accretion disk, in orbit with another star. We report on our use of deep Chandra observations and …
Dust to Dust: Three Years in the Evolution of the Unusual SN 2008S
Garnavich, P. M.; Kochanek, C. S.; Stanek, K. Z. +5 more
We obtained late-time optical and near-IR imaging of SN 2008S with the Large Binocular Telescope, near-IR data with the Hubble Space Telescope, and mid-IR data with the Spitzer Space Telescope. We find that (1) it is again invisible at optical (UBVR) wavelengths to magnitude limits of approximately 25 mag, (2) while detected in the near-IR (H) at …
Hundred Thousand Degree Gas in the Virgo Cluster of Galaxies
Manset, N.; Sparks, W. B.; Pringle, J. E. +6 more
The physical relationship between low-excitation gas filaments at ~104 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ~107 K in the centers of many galaxy clusters is not understood. It is unclear whether the ~104 K filaments have cooled and condensed from the ambient hot (~107
Magnetic Variances and Pitch-angle Scattering Times Upstream of Interplanetary Shocks
Zimbardo, Gaetano; Perri, Silvia
Recent observations of power-law time profiles of energetic particles accelerated at interplanetary shocks have shown the possibility of anomalous, superdiffusive transport for energetic particles throughout the heliosphere. Those findings call for an accurate investigation of the magnetic field fluctuation properties at the resonance frequencies …
Silica-rich Bright Debris Disk around HD 15407A
Onaka, Takashi; Fukagawa, Misato; Murakami, Hiroshi +5 more
We report an intriguing debris disk toward the F3V star HD 15407A in which an extremely large amount of warm fine dust (~10-7 M ⊕) is detected. The dust temperature is derived as ~500-600 K and the location of the debris dust is estimated as 0.6-1.0 AU from the central star, a terrestrial planet region. The fractional luminos…
High Angular Resolution Radio Observations of a Coronal Mass Ejection Source Region at Low Frequencies during a Solar Eclipse
Ramesh, R.; Kathiravan, C.; Barve, Indrajit V. +1 more
We carried out radio observations of the solar corona in the frequency range 109-50 MHz during the annular eclipse of 2010 January 15 from the Gauribidanur Observatory, located about 100 km north of Bangalore in India. The radio emission in the above frequency range originates typically in the radial distance range ≈1.2-1.5 R ⊙ in the "…
Characterizing the Atmospheres of Transiting Planets with a Dedicated Space Telescope
Ollivier, M.; Ribas, I.; Encrenaz, T. +12 more
Exoplanetary science is one of the fastest evolving fields of today's astronomical research, continuously yielding unexpected and surprising results. Ground-based planet-hunting surveys, together with dedicated space missions such as Kepler and CoRoT, are delivering an ever-increasing number of exoplanets, over 690, and ESA's Gaia mission will esc…
The Faint-end Slope of the Redshift 5.7 Lyα Luminosity Function
Martin, Crystal L.; Sawicki, Marcin; Dressler, Alan +2 more
Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultra-faint emission-line galaxies recently reported by Dressler et al. We confirm six Lyα emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s-1 redward of the peak emission. With thes…