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Dust enshrouded star-forming activity in Arp 299
Le Floc'h, E.; Sauvage, M.; Vigroux, L. +4 more
We present mid-infrared spectro-imaging (5-16 µm) observations of the infrared luminous interacting system Arp 299 (= Mrk 171 = IC 694+NGC 3690) obtained with the ISOCAM instrument aboard ISO. Our observations show that nearly 40% of the total emission at 7 and 15 µm is diffuse, originating from the interacting disks of the galaxies. M…
XMM-Newton Observations of Two High-Redshift Quasars: RX J1028-0844 and BR 0351-1034
Elvis, M.; Grupe, D.; Mathur, S. +1 more
We report the results of XMM-Newton observations of two high-redshift quasars, one radio-loud, RX J1028.6-0844 (z=4.276) and one radio-quiet, BR 0351-1034 (z=4.351). We find that the evidence for strong excess absorption toward RX J1028-0844 is marginal at best, contrary to previous claims. The superior sensitivity and broader, softer energy range…
Accuracy of the Born and Ray Approximations for Time-Distance Helioseismology of Flows
Birch, A. C.; Felder, G.
Time-distance helioseismology has been used extensively to study mass flows (for example, flows associated with supergranulation), active regions, and sunspots. In nearly all of these studies the sensitivity of travel times to subsurface flows has been modeled using the first-order ray approximation. The Born approximation has been proposed as a m…
The Stellar Content and Star Formation History of the Late-Type Spiral Galaxy NGC 300 from Hubble Space Telescope Observations
Brandner, W.; Martínez-Delgado, D.; Butler, D. J.
We present the first Hubble Space Telescope (HST) WFPC2 V and I photometry for the Sculptor Group galaxy NGC 300 in four fields ranging from the center to the outer edge. We have made the first measurement of the star formation histories in two disk fields: the oldest stars were born at similar epochs and formation activity increased but at differ…
Supersoft X-Ray Sources in M31. II. ROSAT-detected Supersoft Sources in the ROSAT, Chandra, and XMM-Newton Eras
Greiner, J.; Primini, F.; Di Stefano, R. +1 more
We have performed Chandra observations during the past three years of five of the M31 supersoft X-ray sources discovered with ROSAT. Surprisingly, only one of these sources has been detected, despite a predicted detection of about 20-80 counts for these sources. This has motivated a thorough check of the ROSAT M31 Survey I data, including a relaxa…
Spatially extended K Iλ7699 emission in the nebula of VY CMa: kinematics and geometry
Smith, Nathan
Long-slit echelle spectra reveal bright extended emission from the K Iλ7699 resonance line in the reflection nebula surrounding the extreme red supergiant VY Canis Majoris. The central star has long been known for its unusually bright K I emission lines, but this is the first report of intrinsic emission from K I in the nebula. The extended emissi…
PV Cephei: Young Star Caught Speeding?
Arce, Héctor G.; Goodman, Alyssa A.
Three independent lines of evidence imply that the young star PV Cep is moving at roughly 20 km s-1 through the interstellar medium. The first and strongest suggestion of motion comes from the geometry of the Herbig-Haro (HH) knots in the ``giant'' HH flow associated with PV Cep. Bisectors of lines drawn between pairs of knots at nearly…
XMM-Newton witness of M 86 X-ray metamorphosis
Finoguenov, A.; Pietsch, W.; Aschenbach, B. +1 more
The environmental influence of cluster media on its member galaxies, known as Butcher-Oemler effect, has recently been subject to revision due to numerous observations of strong morphological transformations occurring outside the cluster virial radii, caused by some unidentified gas removal processes. In this context we present new XMM-Newton obse…
An XMM-Newton observation of the nova-like variable UX UMa: spatially and spectrally resolved two-component X-ray emission
Mukai, K.; Pratt, G. W.; Hassall, B. J. M. +2 more
In the optical and ultraviolet regions of the electromagnetic spectrum, UX Ursae Majoris is a deeply eclipsing cataclysmic variable. However, no soft X-ray eclipse was detected in ROSAT observations. We have obtained a 38 ksec XMM-Newton observation to constrain further the origin of the X-rays. The combination of spectral and timing information a…
Low-Mass Pre-Main-Sequence Stars in the Large Magellanic Cloud. III. Accretion Rates from Hubble Space Telescope WFPC2 Observations
Panagia, N.; Robberto, M.; Romaniello, M.
We have measured the present accretion rate of roughly 800 low-mass (~1-1.4 Msolar) pre-main-sequence stars in the field of supernova 1987A in the Large Magellanic Cloud (Z~=0.3 Zsolar). It is the first time that this fundamental parameter for star formation has been determined for low-mass stars outside our Galaxy. The Balme…