Search Publications
The Soft X-ray and Narrow-line Emission of Mrk 573 on Kiloparsec Scales
Acosta-Pulido, J. A.; Gonzalez-Martin, O.; Ramos Almeida, C. +1 more
We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk 573 using Chandra, XMM-Newton, and Hubble Space Telescope (HST) data. We have studied the morphology of the soft (<2 keV) X-rays comparing it with the [O III] and Hα HST images. The soft X-ray emission is resolved into a complex extended region. The X-ray morphology…
Nothing to Hide: An X-ray Survey for Young Stellar Objects in the Pipe Nebula
Forbrich, Jan; Lada, Charles J.; Covey, Kevin R. +1 more
We have previously analyzed sensitive mid-infrared observations to establish that the Pipe Nebula (PiN) has a very low star formation efficiency. That study focused on young stellar objects (YSOs) with excess infrared emission (i.e., protostars and pre-main-sequence stars with disks), however, and could have missed a population of more evolved pre…
Vector Magnetic Fields and Doppler Velocity Structures Around a Cancellation Site in the Quiet Sun
Ichimoto, K.; Iida, Y.; Yokoyama, T.
A cancellation is thought to be a basic process of the photospheric magnetic field and plays an important role in magnetic flux budget and in various solar activities. There are two major theoretical scenarios for this phenomena, the "U-loop emergence" and the "Ω-loop submergence" models. It is important to clarify which is the dominant process du…
Effects of α-Element Enhancement and the Thermally Pulsing-Asymptotic Giant Branch on Surface Brightness Fluctuation Magnitudes and Broadband Colors
Blakeslee, John P.; Worthey, Guy; Lee, Hyun-chul
We investigate the effects of α-element enhancement and the thermally pulsing-asymptotic giant branch (TP-AGB) stars on the surface brightness fluctuation (SBF) magnitudes and broadband colors of simple stellar populations and compare to the empirical calibrations. We consider a broad range of ages and metallicities using the recently updated Tera…
The Asymptotic Giant Branch and the Tip of the Red Giant Branch as Probes of Star Formation History: The Nearby Dwarf Irregular Galaxy KKH 98
Koo, D. C.; Melbourne, J.; Williams, B. +5 more
We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D = 2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (near-IR) Keck Laser Guide Star Adaptive Optics (AO) images resolve 592 IR-bright stars reaching over 1 mag below the tip of the RGB. …
X-ray Emission from the Sombrero Galaxy: Discrete Sources
Spitler, Lee R.; Jones, Christine; Gilfanov, Marat +7 more
We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L X ≈ 1037 erg s-1 and a field of view covering a galactocentric radius of ~30 kpc (11farcm5)…
Chandra Detects the Rare Oxygen-type Wolf-Rayet Star WR 142 and OB Stars in Berkeley 87
Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel +2 more
We present first results of a Chandra X-ray observation of the rare oxygen-type Wolf-Rayet (WR) star WR 142 (= Sand 5 = St 3) harbored in the young, heavily obscured cluster Berkeley 87. Oxygen-type WO stars are thought to be the most evolved of the WRs and progenitors of supernovae or gamma-ray bursts. As part of an X-ray survey of supposedly sin…
On the Constancy of the Electron Temperature in the Expanding Corona Throughout Solar Cycle 23
Morgan, Huw; Habbal, Shadia Rifai; Druckmüller, Miloslav +1 more
A recent analysis of Fe emission lines observed during the total solar eclipses of 2006 March 29 and 2008 August 1 established the first empirical link between the electron temperature in the expanding corona and Fe charge states measured in interplanetary space. In this Letter, we use this link to infer this temperature throughout solar cycle 23 …
High-Resolution X-ray Spectra of the Symbiotic Star SS73 17
Luna, G. J. M.; Smith, R. K.; Eze, R. N. C.
SS73 17 was an innocuous Mira-type symbiotic star until the International Gamma-Ray Astrophysics Laboratory and Swift discovered its bright hard X-ray emission, adding it to the small class of "hard X-ray emitting symbiotics." Suzaku observations in 2006 then showed it emits three bright iron lines as well, with little to no emission in the 0.3-2.…
Swift Study of the First Soft γ-ray Repeater Like Burst from AXP 1E 1841-045 in SNR Kes 73
Safi-Harb, Samar; Kumar, Harsha S.
We report the study of the short (32 ms) and first soft γ-ray repeater like burst observed from the anomalous X-ray pulsar (AXP) 1E 1841-045 associated with the supernova remnant Kes 73, discovered on 2010 May 6 by the Burst Alert Telescope on board the Swift γ-ray observatory. The 15-100 keV time-averaged burst spectrum is modeled by a single pow…