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The Panchromatic Hubble Andromeda Treasury. III. Measuring Ages and Masses of Partially Resolved Stellar Clusters
Bell, Eric F.; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +14 more
The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function (IMF), when inferred from the integrated color of low-mass clusters (lsim104 M ⊙). We use simulated star clusters to show that these effects are minimized when the brightest, rapidly evolving sta…
The Chandra Local Volume Survey: The X-Ray Point-source Catalog of NGC 300
Dalcanton, J. J.; Skillman, E. D.; Kong, A. K. H. +7 more
We present the source catalog of a new Chandra ACIS-I observation of NGC 300 obtained as part of the Chandra Local Volume Survey. Our 63 ks exposure covers ~88% of the D 25 isophote (R ≈ 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance to a limiting unabsorbed 0.35-8 keV luminosity of ~1036
[Fe III] Emission Lines in the Planetary Nebula NGC 2392
Zhang, Y.; Liu, X. -W.; Koning, N. +4 more
NGC 2392 is a young double-shell planetary nebula (PN). Its intrinsic structure and shaping mechanism are still not fully understood. In this paper we present new spectroscopic observations of NGC 2392. The slits were placed at two different locations to obtain the spectra of the inner and outer regions. Several [Fe III] lines are clearly detected…
A Variable Ultraluminous X-Ray Source in a Globular Cluster in NGC 4649
Zezas, A.; Luo, B.; Gallagher, J. S. +9 more
We report the discovery of a new ultraluminous X-ray source associated with a globular cluster in the elliptical galaxy NGC 4649. The X-ray source was initially detected with a luminosity below 5 × 1038 erg s-1, but in subsequent observations 7 and 11 years later it had brightened substantially to 2-3 × 1039 erg s<…
Solar Radio Type-I Noise Storm Modulated by Coronal Mass Ejections
Misawa, H.; Shiota, D.; Inoue, S. +6 more
The first coordinated observations of an active region using ground-based radio telescopes and the Solar Terrestrial Relations Observatory (STEREO) satellites from different heliocentric longitudes were performed to study solar radio type-I noise storms. A type-I noise storm was observed between 100 and 300 MHz during a period from 2010 February 6…
XMM-Newton Finds That SAX J1750.8-2900 May Harbor the Hottest, Most Luminous Known Neutron Star
Heinke, C. O.; Chaty, S.; Tomsick, J. A. +6 more
We have performed the first sensitive X-ray observation of the low-mass X-ray binary (LMXB) SAX J1750.8-2900 in quiescence with XMM-Newton. The spectrum was fit to both a classical blackbody model, and a non-magnetized, pure hydrogen neutron star (NS) atmosphere model. A power-law component was added to these models, but we found that it was not r…
Ultraviolet Spectroscopy of Rapidly Rotating Solar-Mass Stars: Emission-line Redshifts as a Test of the Solar-Stellar Connection
France, Kevin; Linsky, Jeffrey L.; Ayres, Tom +1 more
We compare high-resolution ultraviolet spectra of the Sun and thirteen solar-mass main-sequence stars with different rotational periods that serve as proxies for their different ages and magnetic field structures. In this, the second paper in the series, we study the dependence of ultraviolet emission-line centroid velocities on stellar rotation p…
Flows at the Edge of an Active Region: Observation and Interpretation
Vial, J. -C.; Régnier, S.; Buchlin, E. +1 more
Upflows observed at the edges of active regions have been proposed as the source of the slow solar wind. In the particular case of Active Region (AR) 10942, where such an upflow has been already observed, we want to evaluate the part of this upflow that actually remains confined in the magnetic loops that connect AR 10942 to AR 10943. Both active …
Two-phase ICM in the Central Region of the Rich Cluster of Galaxies A1795: A Joint Chandra, XMM-Newton, and Suzaku View
Makishima, Kazuo; Nakazawa, Kazuhiro; Xu, Haiguang +7 more
Based on a detailed analysis of the high-quality Chandra, XMM-Newton, and Suzaku data of the X-ray bright cluster of galaxies A1795, we report clear evidence for a two-phase intracluster medium (ICM) structure, which consists of a cool (with a temperature T c ≈ 2.0-2.2 keV) and a hot (T h ≈ 5.0-5.7 keV) component that coexist…
High-resolution X-Ray Spectroscopy of the Magnetic Of?p Star HD 148937
Walborn, Nolan R.; Zhekov, Svetozar A.; Nazé, Yaël
High-resolution data of the peculiar magnetic massive star HD 148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800 km s-1), i.e., narrower than the O lin…