Search Publications
Detection of the Detached Dust Shell of U Antliae at Mid-infrared Wavelengths with AKARI/IRC
Onaka, Takashi; Yamamura, Issei; Izumiura, Hideyuki +2 more
We report mid-infrared (MIR) imaging observations of the carbon star U Ant made with the Infrared Camera (IRC) on board AKARI. Subtraction of the artifacts and extended point-spread function of the central star reveals the detached dust shell around the carbon star at MIR wavelengths (15 and 24 µm) for the first time. The observed radial bri…
On the Flare-induced Seismicity in the Active Region NOAA 10930 and Related Enhancement of Global Waves in the Sun
García, R. A.; Tiwari, Sanjiv Kumar; Venkatakrishnan, P. +2 more
A major flare (of class X3.4) occurred on 2006 December 13 in the active region NOAA 10930. This flare event has remained interesting to solar researchers for studies related to particle acceleration during the flare process and the reconfiguration of magnetic fields as well as fine-scale features in the active region. The energy released during f…
The Curious Case of the Alpha Persei Corona: A Dwarf in Supergiant's Clothing?
Ayres, Thomas R.
Alpha Persei (HD 20902: F5 Iab) is a luminous, nonvariable supergiant located at the blue edge of the Cepheid instability strip. It is one of the brightest coronal X-ray sources in the young open cluster bearing its name, yet warm supergiants as a class generally avoid conspicuous high-energy activity. The Cosmic Origins Spectrograph on the Hubble…
Blue Luminous Stars in Nearby Galaxies—UIT 005: A Possible Link to the Luminous Blue Variable Stage
Meynet, G.; Lennon, D. J.; Herrero, A. +2 more
A detailed study of the blue supergiant UIT 005 (B2-2.5Ia+) in M 33 is presented. The results of our quantitative spectral analysis indicate that the star is a very luminous (log L/L sun ~ 5.9 dex) and massive (M ~ 50 M sun) object, showing a very high nitrogen-to-oxygen ratio in its surface (N/O~8, by mass). Based…
The Evolution of Radio Galaxies and X-Ray Point Sources in Coma Cluster Progenitors since z ~ 1.2
Stocke, John T.; Evrard, August E.; Hart, Quyen N. +2 more
Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P 1.4 GHz >= 5 × 1023 W Hz-1 and X-ray point sources (XPSs) at L 0.3-8 keV >= 5 × 1042 erg s-1 in L > L* galaxies in 12 high-redshift (0.4 < z < 1.2) c…
XMM Follow-up Observations of Three Swift BAT-selected Active Galactic Nuclei
Reynolds, C. S.; Mushotzky, R. F.; Koss, M. +2 more
We present XMM-Newton observations of three active galactic nuclei (AGNs) taken as part of a hunt to find very heavily obscured Compton-thick AGNs. For obscuring columns greater than 1025 cm-2, AGNs are only visible at energies below 10 keV via reflected/scattered radiation, characterized by a flat power law. We therefore sel…
Long-term X-ray Variability Study of IC342 from XMM-Newton Observations
Mak, Daisy S. Y.; Pun, Chun S. J.; Kong, Albert K. H.
We presented the results of an analysis of four XMM-Newton observations of the starburst galaxy IC342 taken over a four-year span from 2001 to 2005, with an emphasis on investigating the long-term flux and spectral variability of the X-ray point sources. We detected a total of 61 X-ray sources within 35' × 30' of the galaxy down to a luminosity of…
On the Inversion of Stokes Profiles with Local Stray-light Contamination
Asensio Ramos, A.; Manso Sainz, R.
Obtaining the magnetic properties of non-resolved structures in the solar photosphere is always challenging and problems arise because the inversion is carried out through the numerical minimization of a merit function that depends on the proposed model. We investigate the reliability of inversions in which the stray-light contamination is obtaine…
A Census of Mid-infrared-selected Active Galactic Nuclei in Massive Galaxy Clusters at 0 <~ z <~ 1.3
Saintonge, Amélie; Tran, Kim-Vy H.; Tomczak, Adam R.
We conduct a deep mid-infrared (mid-IR) census of nine massive galaxy clusters at (0 < z < 1.3) with a total of ~1500 spectroscopically confirmed member galaxies using Spitzer/IRAC photometry and established mid-IR color selection techniques. Of the 949 cluster galaxies that are detected in at least three of the four IRAC channels at the >…
Chandra and HST Studies of the X-Ray Sources in Galactic Globular Cluster M92
Anderson, Scott F.; Kong, Albert K. H.; Verbunt, Frank +3 more
We present the analysis of two observations of M92 taken with the Chandra X-Ray Observatory. We combined the two data sets with a total exposure of ~52 ks. With the combined observation, we detected 10 X-ray sources inside the half-mass radius (1farcm02), five of which are inside the core radius (0farcm26) of M92. The luminosities of the 10 source…