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Cassini VIMS Observations Show Ethane is Present in Titan's Rainfall
Nicholson, Philip D.; Sotin, Christophe; Barnes, Jason W. +6 more
Observations obtained over two years by the Cassini Imaging Science Subsystem suggest that rain showers fall on the surface. Using measurements obtained by the Visual Infrared Mapping Spectrometer, we identify the main component of the rain to be ethane, with methane as an additional component. We observe five or six probable rainfall events, at l…
The high-field polar RX J1007.5-2017
Burwitz, V.; Beuermann, K.; Schwope, A. D. +2 more
We report optical and X-ray observations of the high-field polar RX J1007.5-2017 performed between 1990 and 2012. It has an orbital period of 208.60 min determined from the ellipsoidal modulation of the secondary star in an extended low state. The spectral flux of the dM3 - secondary star yields a distance of 790 ± 105 pc. At low accretion levels,…
Ongoing Massive Star Formation in NGC 604
Groves, B.; Brandl, B.; Hunter, D. +1 more
NGC 604 is the second most massive H II region in the Local Group, thus an important laboratory for massive star formation. Using a combination of observational and analytical tools that include Spitzer spectroscopy, Herschel photometry, Chandra imaging, and Bayesian spectral energy distribution fitting, we investigate the physical conditions in N…
A Demonstration of Accurate Wide-field V-band Photometry Using a Consumer-grade DSLR Camera
Maravelias, G.; Eggenstein, H. -B.; Kloppenborg, B. K. +2 more
The authors examined the suitability of using a Digital Single Lens Reflex (DSLR) camera for stellar photometry and, in particular, investigated wide field exposures made with minimal equipment for analysis of bright variable stars. A magnitude-limited sample of stars was evaluated exhibiting a wide range of (B-V) colors taken from four fields bet…
Light echo of V838 Monocerotis: properties of the echoing medium
Tylenda, R.; Kamiński, T.
Context. The light echo phenomenon that accompanied the 2002 eruption of V838 Mon allows one to study the properties of the diffuse dusty matter in the vicinity of the object.
Aims: We are aiming at obtaining estimates of the optical thickness of the circumstellar matter in front of V838 Mon, as well as optical properties of dust grains in th…
From CoRoT 102899501 to the Sun. A time evolution model of chromospheric activity on the main sequence
Deleuil, M.; Fridlund, M.; Gondoin, P. +7 more
Aims: The present study reports measurements of the rotation period of a young solar analogue, estimates of its surface coverage by photospheric starspots and of its chromospheric activity level, and derivations of its evolutionary status. Detailed observations of many young solar-type stars, such as the one reported in the present paper, pro…
A Rare Early-type Star Revealed in the Wing of the Small Magellanic Cloud
Gruendl, R. A.; Hamann, W. -R.; Gallagher, J. S., III +6 more
Sk 183 is the visually brightest star in the N90 nebula, a young star-forming region in the Wing of the Small Magellanic Cloud (SMC). We present new optical spectroscopy from the Very Large Telescope which reveals Sk 183 to be one of the most massive O-type stars in the SMC. Classified as an O3-type dwarf on the basis of its nitrogen spectrum, the…
CO Structure of the 21 µm Source IRAS 22272+5435: A Sign of a Jet Launch?
Zhang, Yong; Kwok, Sun; Yung, Bosco H. K. +3 more
We report the results of radio interferometric observations of the 21 µm source IRAS 22272+5435 in the CO J = 2-1 line. 21 µm sources are carbon-rich objects in the post-asymptotic-giant-branch phase of evolution, which show an unidentified emission feature at 21 µm. Since 21 µm sources usually also have circumstellar molec…
X-Ray and Near-infrared Observations of the Obscured Accreting Pulsar IGR J18179-1621
Nowak, M. A.; Chaty, S.; Rodriguez, J. +6 more
IGR J18179-1621 is an obscured accreting X-ray pulsar discovered by INTEGRAL on 2012 February 29. We report on our 20 ks Chandra-High Energy Transmission Gratings Spectrometer observation of the source performed on 2012 March 17, on two short contemporaneous Swift observations, and on our two near-infrared (Ks , Hn , and J
Determining the North-South Displacement of the Heliospheric Current Sheet from Coronal Streamer Observations
Wang, Y. -M.; Robbrecht, E.
Inferences based on interplanetary field measurements have suggested a statistical tendency for the heliospheric current sheet (HCS) to be displaced southward of the heliographic equator during the past four solar cycles. Here, we use synoptic maps of white-light streamer structures to determine more directly the longitudinally averaged latitude o…