Search Publications
Determination of Magnetic Diffusivity from High-Resolution Solar Magnetograms
Chae, Jongchul; Litvinenko, Yuri E.; Sakurai, Takashi
The magnetic diffusivity in the solar photosphere is determined by applying a new method to the magnetic induction equation. The magnetic field evolution is specified by a time sequence of high-resolution magnetograms of plage regions, taken by Hinode/SOT and SOHO/MDI. The mean value of magnetic diffusivity determined from SOT magnetograms with th…
The Optical Spectra of 24 µm Galaxies in the COSMOS Field. I. Spitzer MIPS Bright Sources in the zCOSMOS-Bright 10k Catalog
Kneib, J. -P.; Maccagni, D.; Aussel, H. +62 more
We study zCOSMOS-bright optical spectra for 609 Spitzer MIPS 24 µm-selected galaxies with S24 µ m > 0.30 mJy and I < 22.5 (AB mag) over 1.5 deg2 of the COSMOS field. From emission-line diagnostics we find the following: (1) SFRs derived from the observed Hα λ6563 and Hβ λ4861 lines underestimate, on average,…
A Puzzling Millisecond Pulsar Companion in NGC 6266
Possenti, A.; Beccari, G.; D'Amico, N. +5 more
We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701-3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red color and an optical variability (~0.2 mag) that nicely correlates with the orbital period of the pulsar (~0.144 days) has been found nearly coincident with th…
Forming Early-Type Galaxies in Groups Prior to Cluster Assembly
Tran, Kim-Vy H.; Moustakas, John; Gonzalez, Anthony H. +3 more
We study a unique protocluster of galaxies, the supergroup SG1120-1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z = 0. SG1120-1202 at z ~ 0.37 is composed of four gravitationally bound groups that ar…
The Evolutionary History of Galactic Bulges: Photometric and Spectroscopic Studies of Distant Spheroids in the GOODS Fields
Treu, Tommaso; Ellis, Richard S.; MacArthur, Lauren A. +3 more
We report on the first results of a new study aimed at understanding the diversity and evolutionary history of distant galactic bulges in the context of now well-established trends for pure spheroidal galaxies. To this end, bulges have been isolated for a sample of 137 spiral galaxies within the redshift range 0.1 < z < 1.2 in the GOODS fiel…
Emerging Active Regions Studied with Ring-Diagram Analysis
Howe, R.; Komm, R.; Hill, F. +1 more
We study the temporal variation of subsurface flows associated with emerging active regions, focusing on four regions in detail. Two of them, AR 10314 and AR 10488, emerge near disk center and the other two, AR 10365 and AR 10375, are older regions where new flux emerges during their disk passage. We measure the horizontal subsurface flows from hi…
Chandra X-Ray Observatory Observations of the Globular Cluster M71
Ransom, Scott M.; Weisskopf, Martin C.; Bogdanov, Slavko +12 more
We observe the nearby, low-density globular cluster M71 (NGC 6838) with the Chandra X-Ray Observatory to study its faint X-ray populations. Five X-ray sources are found inside the cluster core radius, including the known eclipsing binary millisecond pulsar (MSP) PSR J1953+1846A. The X-ray light curve of the source coincident with this MSP shows ma…
On the Magnetic Structure of the Solar Transition Region
Judge, Philip; Centeno, Rebecca
We examine the hypothesis that cool loops dominate emission from solar transition region plasma below temperatures of 2 × 105 K. We compare published VAULT images of H Lyα, a lower transition region line, with nearly contemporaneous magnetograms from Kitt Peak, obtained during the second flight (VAULT-2) on 2002 June 14. The measured su…
Very Large Array Observations of Galactic Center OH 1720 MHz Masers in Sagittarius A East and in the Circumnuclear Disk
Sjouwerman, Loránt O.; Pihlström, Ylva M.
We present Very Large Array (VLA) radio interferometry observations of the 1720 MHz OH masers in the Galactic center (GC). Most 1720 MHz OH masers arise in regions where the supernova remnant Sgr A East is interacting with the interstellar medium. The majority of the newly found 1720 MHz OH masers are located to the northeast, independently indica…
A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations
Miller, J. M.; Muno, M. P.; Gaensler, B. M. +2 more
We present constraints on the number of Galactic magnetars, which we have established by searching for sources with periodic variability in 506 archival Chandra observations and 441 archival XMM-Newton observations of the Galactic plane (| b| < 5°). Our search revealed four sources with periodic variability on timescales of 200-5000 s, all of w…