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X-Ray Fading and Expansion in the “Miniature Supernova Remnant” of GK Persei
Yamaguchi, H.; Uchiyama, Y.; Drake, J. J. +3 more
We report on a second epoch of Chandra X-ray imaging spectroscopy of the spatially resolved old nova remnant GK Persei. An ACIS-S3 observation of 97.4 ks was conducted in 2013 November after a lapse of 13.8 yr from the last visit in 2000. The X-ray emitting nebula appeared more faint and patchy compared with the first epoch. The flux decline was p…
Spatial distribution of ice blocks on Enceladus and implications for their origin and emplacement
Ingersoll, Andrew P.; Ewald, Shawn P.; Helfenstein, Paul +2 more
We have mapped the locations of over 100,000 ice blocks across the south polar region of Saturn's moon Enceladus, thus generating the first quantitative estimates of ice-block number density distribution in relation to major geological features. Ice blocks were manually identified and mapped from twenty of the highest resolution (4-25 m per pixel)…
Wave-like Formation of Hot Loop Arcades
Shestov, S.; Kuzin, S.; Zimovets, I. +2 more
We present observations of hot arcades made with the Mg XII spectroheliograph onboard the CORONAS-F mission, which provides monochromatic images of hot plasma in the Mg XII 8.42 Å resonance line. The arcades were observed to form above the polarity inversion line between active regions NOAA 09847 and 09848 at four successive episodes: at 09:18, 14…
Spectroscopic observations and modelling of impulsive Alfvén waves along a polar coronal jet
Srivastava, A. K.; Murawski, K.; Dwivedi, B. N. +2 more
Context. The magnetic reconnection in the solar corona results in impulsively generated Alfvén waves, which drive a polar jet.
Aims: Using the Hinode/EIS 2'' spectroscopic observations, we study the intensity, velocity, and full width at half maximum (FWHM) variations of the strongest Fe XII 195.12 Å line along the jet to find the signature o…
ALMA Observations of the Largest Proto-Planetary Disk in the Orion Nebula, 114-426: A CO Silhouette
Di Francesco, James; Johnstone, Doug; Matthews, Brenda +7 more
We present ALMA observations of the largest protoplanetary disk in the Orion Nebula, 114-426. Detectable 345 GHz (856 µm) dust continuum is produced only in the 350 AU central region of the ∼1000 AU diameter silhouette seen against the bright {{H}}α background in Hubble Space Telescope images. Assuming optically thin dust emission at 345 GHz…
A Stacked Search for Intermediate-mass Black Holes in 337 Extragalactic Star Clusters
Miller-Jones, J. C. A.; Wrobel, J. M.; Nyland, K. E.
Forbes et al. recently used the Hubble Space Telescope to localize hundreds of candidate star clusters in NGC 1023, an early-type galaxy at a distance of 11.1 Mpc. Old stars dominate the light of 92% of the clusters and intermediate-age stars dominate the light of the remaining 8%. Theory predicts that clusters with such ages can host intermediate…
Motion of reconnection region in the Earth's magnetotail
Nakamura, Rumi; Semenov, Vladimir S.; Nakamura, Takuma K. M. +1 more
We obtain the X-line velocity in the Earth's magnetotail for 24 reconnection events observed by the Cluster spacecraft between 2001 and 2005. The data set consists of 10 single X-lines and 14 X-lines from the time intervals of multiple reconnection. Except for two X-lines from multiple reconnection, all the X-lines move tailward (radial outward) a…
Solar Dynamics, Rotation, Convection and Overshoot
Thompson, M. J.; Schou, J.; Roth, M. +3 more
We discuss recent observational, theoretical and modeling progress made in understanding the Sun's internal dynamics, including its rotation, meridional flow, convection and overshoot. Over the past few decades, substantial theoretical and observational effort has gone into appreciating these aspects of solar dynamics. A review of these observatio…
SHARDS: A Global View of the Star Formation Activity at z ~ 0.84 and z ~ 1.23
Barro, Guillermo; Pérez-González, Pablo G.; Koekemoer, Anton M. +22 more
In this paper, we present a comprehensive analysis of star-forming galaxies (SFGs) at intermediate redshifts (z ∼ 1). We combine the ultra-deep optical spectro-photometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) with deep UV-to-FIR observations in the GOODS-N field. Exploiting two of the 25 SHARDS medium-band filte…
Discovery of Resolved Debris Disk around HD 131835
Chen, Christine H.; Fitzgerald, Michael P.; Graham, James R. +3 more
We report the discovery of the resolved disk around HD 131835 and present the analysis and modeling of its thermal emission. HD 131835 is a ∼15 Myr A2 star in the Scorpius-Centaurus OB association at a distance of 122.7-12.8+16.2 pc . The extended disk has been detected to ∼ 1\buildrel{\prime\prime}\over{.} 5 (200 AU) at 11.7…