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A Nearby Analog of z ~ 2 Compact Quiescent Galaxies with a Rotating Disk
Franx, Marijn; van Dokkum, Pieter; Bezanson, Rachel +1 more
Recent studies have identified a population of compact quiescent galaxies at z ~ 2. These galaxies are very rare today and establishing the existence of a nearby analog could allow us to study its structure in greater detail than is possible at high redshift. Here we present such a local analog, NGC 5845, which has a dynamical mass of M dyn
Ionized Gas in the First 10 kpc of the Interstellar Galactic Halo: Metal Ion Fractions
Howk, J. Christopher; Consiglio, S. Michelle
We present direct measures of the ionization fractions of several sulfur ions in the Galactic warm ionized medium (WIM). We obtained high-resolution ultraviolet absorption-line spectroscopy of post-asymptotic giant branch stars in the globular clusters Messier 3 [(l, b) = (42fdg2, +78fdg7), d = 10.2 kpc, and z = 10.0 kpc] and Messier 5 [(l, b) = (…
Solar-cycle Variation of Sound Speed near the Solar Surface
Rabello-Soares, M. C.
We present evidence that the sound-speed variation with solar activity has a two-layer configuration, similar to the one observed below an active region, which consists of a negative layer near the solar surface and a positive one in the layer immediately below the first one. Frequency differences between the activity minimum and maximum of solar …
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…
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 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…
Extreme-ultraviolet Spectroscopic Observation of Direct Coronal Heating during a C-class Solar Flare
Brosius, Jeffrey W.
With the Coronal Diagnostic Spectrometer operating in rapid cadence (9.8 s) stare mode during a C6.6 flare on the solar disk, we observed a sudden brightening of Fe XIX line emission (formed at temperature T ≈ 8 MK) above the pre-flare noise without a corresponding brightening of emission from ions formed at lower temperatures, including He I (0.0…