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Comparison of Solar Subsurface Flows Assessed by Ring and Time-Distance Analyses
Gizon, Laurent; Duvall, Thomas L., Jr.; Toomre, Juri +2 more
The solar near-surface shear layer exhibits a rich medley of flows that are now being measured by a variety of local helioseismic techniques. We present comparisons of the horizontal flows obtained with two of these techniques, ring and time-distance analyses, applied to Michelson Doppler Imager (MDI) Dynamics Program data from the years 1998 and …
M31 Globular Cluster X-Ray Sources: XMM-Newton and Chandra Results
Trudolyubov, Sergey; Priedhorsky, William
We present the results of an M31 globular cluster (GC) X-ray source survey, based on the data of XMM-Newton and Chandra observations covering ~6100 arcmin2 of M31. We detected 43 X-ray sources coincident with GC candidates from various optical surveys. The inferred isotropic X-ray luminosities of GC sources lie between ~1035 …
The Stellar Content of the Southern Tail of NGC 4038/4039 and a Revised Distance
Rich, R. Michael; Saviane, Ivo; Hibbard, J. E.
We have used the Hubble Space Telescope and Wide Field Planetary Camera 2 to image the putative tidal dwarf galaxy located at the tip of the Southern tidal tail of NGC 4038/4039, the Antennae. We resolve individual stars and identify two stellar populations. Hundreds of massive stars are present, concentrated into tight OB associations on scales o…
XMM-Newton observations of the σ Ori cluster. I. The complex RGS spectrum of the hot star σ Ori AB
Pallavicini, R.; Franciosini, E.; Sanz-Forcada, J.
We present XMM-Newton observations of the young ({∼} 2{-}5 Myr) cluster around the hot (O9.5V) star σ Orionis AB, aimed at obtaining a high resolution RGS spectrum of the hot star as well as EPIC imaging data for the whole field. We show that the RGS spectrum of σ Ori AB may be contaminated by weaker nearby sources which required the development o…
Inferring of flux rope orientation with the minimum variance analysis technique
Fu, S. Y.; Pu, Z. Y.; Zong, Q. G. +3 more
The accuracy in flux rope orientation inference from both the traditional magnetic-field-based minimum variance analysis (BMVA) technique and the current-based MVA (CMVA) approach is examined. Four different flux rope models are used in the MVA test. It is found that the directions of eigenvectors of MVA are critically dependent on the spacecraft …
Radial Velocity Studies of Close Binary Stars. IX.
Rucinski, Slavek M.; Capobianco, Christopher C.; DeBond, Heide +8 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the eighth set of 10 close binary systems: AB And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP Peg, and V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori, and V335 Peg) were discovered photometric…
Smashing the Guitar: An Evolving Neutron Star Bow Shock
Chatterjee, S.; Cordes, J. M.
The Guitar Nebula is a spectacular example of an Hα bow shock nebula produced by the interaction of a neutron star with its environment. The radio pulsar B2224+65 is traveling at ~800-1600 km s-1 (for a distance of 1-2 kpc), placing it on the high-velocity tail of the pulsar velocity distribution. Here we report time evolution in the sh…
Truncation of stellar disks in galaxies at z ≈ 1
Pérez, I.
We report here the first evidence for stellar disk truncation at high redshift, based on surface photometry of a sample of 16 high redshift (0.6<z<1.0) disk galaxies from the GOODS HST/ACS data. The radial profiles are best fit by a double exponential profile. This result agrees with the profile of disks in local galaxies. The cosmological s…
A Hubble Space Telescope WFPC2 Investigation of the Disk-Halo Interface in NGC 891
Norman, Colin A.; Dettmar, Ralf-Jürgen; Rossa, Jörn +1 more
We present deep narrowband observations with high spatial resolution of extraplanar diffuse ionized gas in the halo of NGC 891, obtained with the WFPC2 on board the HST. Our Hα observations, centered on the northern part of NGC 891, reveal an extended gaseous halo, which fills almost the entire field of view of our WFPC2 observation. Whereas NGC 8…
Discovery of X-ray absorption features from the dipping low-mass X-ray binary XB 1916-053 with XMM-Newton
Parmar, A. N.; Boirin, L.; Paltani, S. +2 more
We report the discovery of narrow Fe XXV and Fe XXVI Kα X-ray absorption lines at 6.65+0.05-0.02 and 6.95+0.05-0.04 keV in the persistent emission of the dipping low-mass X-ray binary (LMXB) XB 1916-053 during an XMM-Newton observation performed in September 2002. In addition, there is marginal evidence …