Search Publications
Explanation of a Special Color-Magnitude Diagram of Star Cluster NGC 1651 from Different Models
Chen, Li; Li, Zhongmu; Mao, Caiyan
The color-magnitude diagram (CMD) of globular cluster NGC 1651 has special structures including a broad main sequence, an extended main sequence turn-off, and an extended red giant clump. The reason for such a special CMD remains unclear. In order to test the difference among the results from various stellar population assumptions, we study a high…
Probing Wolf-Rayet Winds: Chandra/HETG X-Ray Spectra of WR 6
Hamann, W. -R.; Huenemoerder, David P.; Ignace, R. +6 more
With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. …
Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets
Sekanina, Zdenek; Kracht, Rainer
We investigate the relationships among the angular orbital elements—the longitude of the ascending node Ω, the inclination i, and the argument of perihelion ω—of the Kreutz system’s faint, dwarf sungrazers observed only with the Solar and Heliospheric Observatory/STEREO coronagraphs; their published orbits were derived using a parabolic, purely gr…
Dark Jets in Solar Coronal Holes
Young, Peter R.
A new solar feature termed a dark jet is identified from observations of an extended solar coronal hole that was continuously monitored for over 44 hr by the Extreme Ultraviolet Imaging Spectrometer on board the Hinode spacecraft in 2011 February 8-10 as part of Hinode Operation Plan No. 177 (HOP 177). Line of sight (LOS) velocity maps derived fro…
Photometry of Pluto 2008-2014: Evidence of Ongoing Seasonal Volatile Transport and Activity
Buratti, B. J.; Dalba, P. A.; Hillier, J. K. +6 more
The New Horizons spacecraft will encounter Pluto in 2015 July. As this fast flyby will yield a picture of Pluto frozen in time, ground-based observations are key to understanding this dwarf ice planet, especially with regard to the seasonal transport of surface volatiles. This paper reports on changes in Pluto's rotational light curve as evidence …
The Progenitor of the FUor-Type Young Eruptive Star 2MASS J06593158-0405277
Ábrahám, P.; Kóspál, Á.; Moór, A. +3 more
Only a dozen confirmed FU Orionis-type young outbursting stars (FUors) are known today; this explains the interest in the recent FUor eruption of 2MASS J06593158-0405277. Its outburst and expected decline will be subject to numerous studies in the future. Almost equally important for the understanding of the eruption mechanism, however, is the phy…
XMM-Newton and Suzaku X-Ray Shadowing Measurements of the Solar Wind Charge Exchange, Local Bubble, and Galactic Halo Emission
Henley, David B.; Shelton, Robin L.
We present results from a sample of XMM-Newton and Suzaku observations of interstellar clouds that cast shadows in the soft X-ray background (SXRB)—the first uniform analysis of such a sample from these missions. By fitting to the on- and off-shadow spectra, we separated the foreground and Galactic halo components of the SXRB. We tested different …
Prevailing Dust-transport Directions on Comet 67P/Churyumov-Gerasimenko
Kramer, Tobias; Noack, Matthias
Dust transport and deposition behind larger boulders on the comet 67P/Churyumov-Gerasimenko (67P/C-G) have been observed by the Rosetta mission. We present a mechanism for dust-transport vectors based on a homogeneous surface activity model incorporating in detail the topography of 67P/C-G. The combination of gravitation, gas drag, and Coriolis fo…
UV Insights into the Complex Populations of M87 Globular Clusters
Anderson, J.; Milone, A. P.; Bedin, L. R. +7 more
We have imaged with Hubble Space Telescope WFC3/UVIS the central 2\buildrel{ \prime}\over{.} 7× 2\buildrel{ \prime}\over{.} 7 region of the giant elliptical galaxy M87, using the ultraviolet filter F275W. In combination with archival ACS/WFC data taken through the F606W and F814W filters, covering the same field, we have constructed integrated-lig…
Far-Infrared and Accretion Luminosities of the Present-day Active Galactic Nuclei
Woo, Jong-Hak; Matsuoka, Kenta
We investigate the relation between star formation (SF) and black hole accretion luminosities, using a sample of 492 type-2 active galactic nuclei (AGNs) at z\lt 0.22, which are detected in the far-infrared (FIR) surveys with AKARI and Herschel. We adopt FIR luminosities at 90 and 100 µm as SF luminosities, assuming the proposed linear propo…