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A Spitzer Study of Asymptotic Giant Branch Stars. III. Dust Production and Gas Return in Local Group Dwarf Irregular Galaxies
Skillman, Evan D.; Boyer, Martha L.; Gehrz, Robert D. +2 more
We present the third and final part of a census of asymptotic giant branch (AGB) stars in Local Group dwarf irregular (dIrr) galaxies. Papers I and II presented the results for WLM and IC 1613. Included here are Phoenix, LGS 3, DDO 210, Leo A, Pegasus dIrr, and Sextans A. Spitzer photometry at 3.6, 4.5, 5.8, and 8 µm are presented, along wit…
Numerical Simulation of Excitation and Propagation of Helioseismic MHD Waves: Effects of Inclined Magnetic Field
Kosovichev, A. G.; Parchevsky, K. V.
Investigation of propagation, conversion, and scattering of MHD waves in the Sun is very important for understanding the mechanisms of observed oscillations and waves in sunspots and active regions. We have developed a three-dimensional linear MHD numerical model to investigate the influence of the magnetic field on excitation and properties of th…
The Ultraviolet Spectrum and Physical Properties of the Mass Donor Star in HD 226868 = Cygnus X-1
Kaper, L.; Herrero, A.; Bolton, C. T. +8 more
We present an examination of high-resolution, ultraviolet (UV) spectroscopy from Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the massive X-ray binary HD 226868 = Cyg X-1. We analyzed this and ground-based optical spectra to determine the effective temperature and gravity of the O9.7 Iab supergiant. Using non-LTE, lin…
Sizes of LYα-emitting Galaxies and Their Rest-frame Ultraviolet Components at z = 3.1
Schawinski, Kevin; Gronwall, Caryl; Gawiser, Eric +3 more
We present a rest-frame ultraviolet analysis of ~120 z ~ 3.1 Lyman Alpha Emitters (LAEs) in the Extended Chandra Deep Field South. Using Hubble Space Telescope (HST) images taken as part of the Galaxy Evolution From Morphology and SEDS (GEMS) survey, Great Observatories Origins Deep Survey (GOODS), and Hubble Ultradeep Field surveys, we analyze th…
The ACS Nearby Galaxy Survey Treasury. II. Young Stars and their Relation to Hα and UV Emission Timescales in the M81 Outer Disk
de Jong, Roelof S.; Williams, Benjamin F.; Dolphin, Andrew +11 more
We have obtained resolved stellar photometry from Hubble Space Telescope Advanced Camera for Surveys observations of a field in the outer disk of M81 as part of ANGST. Motivated by the recent discovery of extended UV disks around many nearby spiral galaxies, we use the observed stellar population to derive the recent star formation histories of fi…
IGR J17544-2619 in Depth With Suzaku: Direct Evidence for Clumpy Winds in a Supergiant Fast X-ray Transient
Smith, David M.; Negueruela, Ignacio; Rampy, Rachel A.
We present direct evidence for dense clumps of matter in the companion wind in a Supergiant Fast X-ray Transient (SFXT) binary. This is seen as a brief period of enhanced absorption during one of the bright, fast flares that distinguish these systems. The object under study was IGR J17544-2619, and a total of 236 ks of data were accumulated with t…
Infrared Luminosities and Dust Properties of z ≈ 2 Dust-obscured Galaxies
Le Floc'h, E.; Dey, Arjun; Bussmann, R. S. +6 more
We present SHARC-II 350 µm imaging of twelve 24 µm bright (F 24 µm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Boötes field of the NOAO Deep Wide-Field Survey. Detections of fou…
Does Stellar Feedback Create H I Holes? A Hubble Space Telescope/Very Large Array Study of Holmberg II
Cannon, John M.; Dolphin, Andrew E.; Skillman, Evan D. +4 more
We use deep Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) F555W and F814W photometry of resolved stars in the M81 Group dwarf irregular galaxy Ho II to study the hypothesis that the holes identified in the neutral interstellar medium (H I) are created by stellar feedback. From the deep photometry, we construct color-magnitude diag…
Initiation of Coronal Mass Ejections in a Global Evolution Model
Yeates, A. R.; Mackay, D. H.
Loss of equilibrium of magnetic flux ropes is a leading candidate for the origin of solar coronal mass ejections (CMEs). The aim of this paper is to explore to what extent this mechanism can account for the initiation of CMEs in the global context. A simplified MHD model for the global coronal magnetic field evolution in response to flux emergence…
The Size-Star Formation Relation of Massive Galaxies at 1.5 < z < 2.5
Wuyts, S.; Förster Schreiber, N. M.; Toft, S. +4 more
We study the relation between size and star formation activity in a complete sample of 225 massive (M * > 5 × 1010 M sun) galaxies at 1.5 < z < 2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed rest-frame UV-NIR spectral energy dist…