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An X-Ray Spectral Analysis of the Central Regions of NGC 4593
Kaiser, Mary Elizabeth; Brenneman, Laura W.; Wilms, Jörn +1 more
We present a detailed analysis of XMM-Newton EPIC-pn data for the Seyfert 1 galaxy NGC 4593. We discuss the X-ray spectral properties of this source, as well as its variations with time. The 0.5-10 keV spectrum shows significant complexity beyond a simple power-law form, with clear evidence existing for a ``soft excess,'' as well as absorption by …
The Star-forming Region NGC 346 in the Small Magellanic Cloud with Hubble Space Telescope ACS Observations. II. Photometric Study of the Intermediate-Age Star Cluster BS 90
Henning, Thomas; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +2 more
We present the results of our investigation of the intermediate-age star cluster BS 90, located in the vicinity of the H II region N66 in the SMC, observed with HST ACS. The high-resolution data provide a unique opportunity for a very detailed photometric study performed on one of the rare intermediate-age rich SMC clusters. The complete set of ob…
Adaptive Optics Imaging of IRAS 18276-1431: A Bipolar Preplanetary Nebula with Circumstellar ``Searchlight Beams'' and ``Arcs''
Sahai, R.; Sánchez Contreras, C.; Le Mignant, D. +2 more
We present high angular resolution images of the post-AGB nebula IRAS 18276-1431 (also known as OH 17.7-2.0) obtained with the Keck II adaptive optics (AO) system in its natural guide star (NGS) mode in the Kp, Lp, and Ms near-infrared bands. We also present supporting optical F606W and F814W HST images as well as …
Chandra and XMM-Newton Discovery of Transient X-Ray Pulsar in the Nearby Spiral Galaxy NGC 2403
Córdova, France A.; Trudolyubov, Sergey P.; Priedhorsky, William C.
We report on the discovery and analysis of the transient X-ray pulsar CXOU J073709.1+653544 detected in the 2004 August-October Chandra and XMM-Newton observations of the nearby spiral galaxy NGC 2403. The X-ray source exhibits X-ray pulsations with a period P~18 s and a nearly sinusoidal pulse shape and pulsed fraction 46%-70% during the first th…
The CME Acceleration Problem: Error Estimates in LASCO Coronal Mass Ejection Measurements
Wen, Yayuan; Wang, Jingxiu; Maia, Dalmiro Jorge Filipe
The properties of the coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph Experiment (LASCO) on the Solar and Heliospheric Observatory (SOHO) spacecraft are kept in an online catalog that has been widely used in a series of analyses of individual events and in statistical overviews of CME properties. A subject o…
Multiple Coaxial Rings in the Bipolar Nebula Hubble 12
Kwok, Sun; Hsia, Chih Hao
A series of two-dimensional rings along a common axis aligned with the bipolar lobes is found in the planetary nebula Hb 12. The rings have separations of about 0.3", which can be translated into physical separations of ~1000 AU, or time separations of the order of 50 yr. We suggest that the existence of the rings is a manifestation of the interac…
Magnetic Evolution and Temperature Variation in a Coronal Hole
Zhang, Jun; Wang, Haimin; Wang, Jingxiu +1 more
We have explored the magnetic flux evolution and temperature variation in a coronal hole region, using Big Bear Solar Observatory deep magnetograms and SOHO EIT images observed from 2005 October 10 to 14. For comparison, we also investigated a neighboring quiet region of the Sun. The coronal hole evolved from its mature stage to its disappearance …
A Far-Ultraviolet Study of the Nova-like V794 Aquilae
Szkody, Paula; Sion, Edward M.; Godon, Patrick +1 more
V794 Aql was observed in a high state with the Hubble Space Telescope Space Telescope Imaging Spectrograph (HST STIS) on 2003 August 28, and with the Far Ultraviolet Spectroscopic Explorer (FUSE) on 2004 May 13. We present here a spectral analysis of the FUSE and HST STIS spectra. For a 0.9 Msolar, the best fit is an accretion disk with…
AEGIS: A Panchromatic Study of IRAC-selected Extremely Red Objects with Confirmed Spectroscopic Redshifts
Barmby, P.; Papovich, C.; Rigopoulou, D. +17 more
We study 87 extremely red objects (EROs), selected both to have color redder than R-[3.6]=4.0 and to have confirmed spectroscopic redshifts. Together, these two constraints result in this sample populating a fairly narrow redshift range at 0.76<z<1.42. The key new ingredient included here is deep Spitzer Space Telescope Infrared Array Camera…
Micro-Type III Radio Bursts
Morioka, Akira; Miyoshi, Yoshizumi; Masuda, Satoshi +5 more
We present a detailed description of the features of solar ``micro-type III'' radio bursts, which are elements of the so-called type III storms, using long-term observations made by the Geotail and Akebono satellites. Micro-type III bursts are characterized by short-lived, continuous, and weak emission. Their average power is estimated to be well …