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Superorbital Modulation of X-Ray Emission from Gamma-Ray Binary LSI +61 303
Lutovinov, A.; Molkov, S.; Chernyakova, M. +3 more
We report the discovery of a systematic constant time lag between the X-ray and radio flares of the gamma-ray binary LSI +61 303, persistent over a long, multi-year timescale. Using the data from the monitoring of the system by RXTE we show that the orbital phase of X-ray flares from the source varies from phi X ~= 0.35 to phi X <…
Recurrent dust formation by WR 48a on a 30-year time-scale
Marang, Fred; Whitelock, Patricia A.; Williams, Peredur M. +4 more
We present infrared photometry of the WC8 Wolf-Rayet system WR 48a observed with telescopes at the European Southern Observatory, the South African Astronomical Observatory and the Anglo Australian Telescope between 1982 and 2011, which show a slow decline in dust emission from the previously reported outburst in 1978-79 until about 1997, when sig…
Revealing Companions to Nearby Stars with Astrometric Acceleration
Tokovinin, Andrei; Makarov, Valeri V.; Hayward, Thomas L. +1 more
A subset of 51 Hipparcos astrometric binaries among FG dwarfs within 67 pc has been surveyed with the Near-Infrared Coronagraphic Imager adaptive optics system at Gemini-S, directly resolving for the first time 17 subarcsecond companions and 7 wider ones. Using these data together with published speckle interferometry of 57 stars, we compare the s…
Ammonia and other parent molecules in comet 10P/Tempel 2 from Herschel/HIFI and ground-based radio observations
Küppers, M.; Hartogh, P.; Crovisier, J. +12 more
The Jupiter-family comet 10P/Tempel 2 was observed during its 2010 return with the Herschel Space Observatory. We present here the observation of the JK (10-00) transition of NH3 at 572 GHz in this comet with the Heterodyne Instrument for the Far Infrared (HIFI) of Herschel. We also report on radio obser…
Quantifying the universality of the stellar initial mass function in old star clusters
Sills, Alison; Sarajedini, Ata; de Marchi, Guido +4 more
We present a new technique to quantify cluster-to-cluster variations in the observed present-day stellar mass functions of a large sample of star clusters. Our method quantifies these differences as a function of both the stellar mass and the total cluster mass, and offers the advantage that it is insensitive to the precise functional form of the …
A Variable Partial Covering Model for the Seyfert 1 Galaxy MCG -6-30-15
Ebisawa, Ken; Inoue, Hajime; Miyakawa, Takehiro
We propose a simple spectral model for the Seyfert 1 Galaxy MCG -6-30-15 that can explain most of the 1-40 keV spectral variation by a change of the partial covering fraction, similar to that proposed by Miller, Turner, and Reeves (2008, A&A, 483, 437). Our spectral model is composed of three continuum components: (1) a direct power-law compon…
A Population of Dust-rich Quasars at z ~ 1.5
Elvis, Martin; Willmer, Christopher N. A.; Magdis, Georgios E. +19 more
We report Herschel SPIRE (250, 350, and 500 µm) detections of 32 quasars with redshifts 0.5 <=z < 3.6 from the Herschel Multi-tiered Extragalactic Survey (HerMES). These sources are from a MIPS 24 µm flux-limited sample of 326 quasars in the Lockman Hole Field. The extensive multi-wavelength data available in the field permit con…
Star Formation History in Two Fields of the Small Magellanic Cloud Bar
Anderson, J.; Cignoni, M.; Tosi, M. +5 more
The Bar is the most productive region of the Small Magellanic Cloud in terms of star formation but also the least studied one. In this paper, we investigate the star formation history of two fields located in the SW and in the NE portion of the Bar using two independent and well-tested procedures applied to the color-magnitude diagrams of their st…
Direct imaging of extra-solar planets in star forming regions. Lessons learned from a false positive around IM Lupi
Absil, O.; Augereau, J. -C.; Surdej, J. +8 more
Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1-5 µm). Because of these practical limitations, our current observational aim at detecting and characterizing pl…
Star Formation and AGN Activity in Galaxies Classified Using the 1.6 µm Bump and PAH Features at z = 0.4-2
Goto, Tomotsugu; Oyabu, Shinki; Ohyama, Youichi +17 more
We studied the star-formation and AGN activity of massive galaxies in the redshift range