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Hot Horizontal Branch Stars in ω Centauri: Clues about their Origin from the Cluster Color Magnitude Diagram
Anderson, Jay; Salaris, Maurizio; Bedin, Luigi R. +5 more
We investigate a peculiar feature at the hottest, blue end of the horizontal branch of Galactic globular cluster ω Centauri, using the high-precision and nearly complete catalog that has been constructed from a survey taken with the Advanced Camera for Survey on board the Hubble Space Telescope, that covers the inner 10 × 10 arcmin. It is a densel…
Dynamical Mass of the M8+M8 Binary 2MASS J22062280 - 2047058AB
Dupuy, Trent J.; Bowler, Brendan P.; Liu, Michael C.
We present Keck laser guide star adaptive optics imaging of the M8+M8 binary 2MASS J2206 - 2047AB. Together with archival Hubble Space Telescope, Gemini-North, and Very Large Telescope data, our observations span 8.3 yr of the binary's 35+6 -5 yr orbital period, and we determine a total dynamical mass of 0.15+0.05 …
Conversion from Explosive to Gentle Chromospheric Evaporation During a Solar Flare
Brosius, Jeffrey W.
A GOES M1.5 solar flare was observed in NOAA AR 10652 on 2004 July 27 around 20:00 UT with the Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft. Images obtained with SOHO's Extreme-ultraviolet Imaging Telescope and with the Transition Region And Coronal Explorer satellite show that the CDS slit …
The Discovery of Remote Globular Clusters in M33
Chapman, S. C.; Tanvir, N. R.; Ferguson, A. M. N. +5 more
We present the discovery of four remote star clusters in M33, one of which is of an extended nature. Three of the clusters were discovered using survey data from the Isaac Newton Telescope Wide-Field Camera while one was discovered serendipitously in a deep image taken with the Hubble Space Telescope's Advanced Camera for Surveys. With projected r…
Coronal Mass Ejections and Global Coronal Magnetic Field Reconfiguration
Vourlidas, Angelos; Bale, Stuart D.; Liu, Ying +3 more
We investigate the role of coronal mass ejections (CMEs) in the global coronal magnetic field reconfiguration, a debate that has lasted for about two decades. Key evidence of the coronal field restructuring during the 2007 December 31 CME is provided by combining imaging observations from widely separated spacecraft with the potential-field source…
The Relationship between Coronal Dimming and Coronal Mass Ejection Properties
Biesecker, D. A.; Reinard, A. A.
Coronal dimmings are closely related to the footpoints of coronal mass ejections (CMEs) and, as such, offer information about CME origins and evolution. In this paper, we investigate the relationship between CME and dimming properties. In particular, we compare CME quantities for events with and without associated dimmings. We find that dimming-as…
Discrepant Mass Estimates in the Cluster of Galaxies Abell 1689
Garmire, G. P.; Bautz, M. W.; Andersson, K. +1 more
We present a new mass estimate of a well studied gravitational lensing cluster, Abell 1689, from deep Chandra observations with a total exposure of 200 ks. Within r = 200 h -1 kpc, the X-ray mass estimate is systematically lower than that of lensing by 30%-50%. At r>200 h -1 kpc, the mass density profiles from X-ray and we…
The Discovery of a Very Faint X-Ray Transient in the Globular Cluster M15
Heinke, Craig O.; Cohn, Haldan N.; Lugger, Phyllis M.
We have identified an X-ray transient (hereafter M15 X-3) in the globular cluster M15 from an archival Chandra grating observation. M15 X-3 appears at an X-ray luminosity of 6 × 1033 erg s-1 with a spectrum consistent with an absorbed power law of photon index 1.51 ± 0.14. The object is identifiable in archival Chandra HRC-I …
A Survey of Coronal Cavity Density Profiles
Gibson, S. E.; Fuller, J.
Coronal cavities are common features of the solar corona that appear as darkened regions at the base of coronal helmet streamers in coronagraph images. Their darkened appearance indicates that they are regions of lowered density embedded within the comparatively higher density helmet streamer. Despite interfering projection effects of the surround…
Is the Black Hole in GX 339-4 Really Spinning Rapidly?
Takahashi, H.; Gandhi, P.; Yamada, S. +7 more
The wide-band Suzaku spectra of the black hole (BH) binary GX 339-4, acquired in 2007 February during the Very High state, were reanalyzed. Effects of event pileup (significant within ~3' of the image center) and telemetry saturation of the X-ray Imaging Spectrometer (XIS) data were carefully considered. The source was detected up to ~300 keV, wit…