Search Publications
The brightest stars of the σ Orionis cluster
Caballero, J. A.
Context: The very young σ Orionis cluster (~3 Ma) is a cornerstone in understanding the formation of stars and substellar objects down to planetary masses. However, its stellar population is far from being completely known.
Aims: This study's purpose is to identify and characterise the most massive stars of σ Orionis to complement current and …
The Relaxation of Sheared Magnetic Fields: A Contracting Process
Wang, Haimin; Ji, Haisheng; Huang, Guangli
In recent years, several authors have reported a contracting motion for solar flaring loops. That is, during the rising phase of solar flares, hard X-ray (HXR) loop-top sources or radio/extreme-ultraviolet (EUV) flaring loops have a descending motion and, at the same time, Hα ribbons or HXR footpoints (FPs) are converging. The usual expansion moti…
A View of the M81 Galaxy Group via the Hα Window
Karachentsev, Igor D.; Kaisin, Serafim S.
We present images for 36 galaxies of the M81 Group obtained in the Hα line. Estimates of the Hα flux and star formation rate (SFR) are now available for all the known members of the group with absolute magnitudes down to MB=-10 mag. The character of distribution of the galaxies over three parameters, MB, SFR, and total hydrog…
In/Out Pairs and the Detachment of Coronal Streamers
Sheeley, N. R., Jr.; Wang, Y. -M.
We previously described coronal events that originate in the 2-6 Rsolar field of view of the LASCO white-light coronagraph and involve the simultaneous ejection of material inward toward the Sun and outward away from it. Now, in a study of more than 160 in/out pairs, we have found that these features are density enhancements at the lead…
A belt of moonlets in Saturn's A ring
Schmidt, Jürgen; Sremčević, Miodrag; Albers, Nicole +3 more
The origin and evolution of planetary rings is one of the prominent unsolved problems of planetary sciences, with direct implications for planet-forming processes in pre-planetary disks. The recent detection of four propeller-shaped features in Saturn's A ring proved the presence of large boulder-sized moonlets in the rings. Their existence favour…
Energy Release Rates along Hα Flare Ribbons and the Location of Hard X-Ray Sources
Temmer, M.; Veronig, A. M.; Vršnak, B. +1 more
Local reconnection and energy release rates for an X3.8 flare that occurred on 2005 January 17 are derived. In particular, we distinguish between Hα flare ribbon segments that were accompanied by RHESSI hard X-ray (HXR) footpoints and those without HXRs. We find that the reconnection and energy release rates are not uniform along the flare ribbons…
An Atlas of the Circumnuclear Regions of 75 Seyfert Galaxies in the Near-Ultraviolet with the Hubble Space Telescope Advanced Camera for Surveys
Leitherer, Claus; Storchi-Bergmann, Thaisa; Pérez, Enrique +5 more
We present an atlas of the central regions of 75 Seyfert galaxies imaged in the near-UV with the Advanced Camera for Surveys of the Hubble Space Telescope at an average resolution of ~10 pc. These data complement archival high-resolution data from the Hubble Space Telescope at optical and near-IR wavelengths, creating an extremely valuable data se…
Geomorphic and stratigraphic analysis of Crater Terby and layered deposits north of Hellas basin, Mars
Moore, Jeffrey M.; Wilson, Sharon A.; Howard, Alan D. +1 more
The geologic history of Crater Terby is developed through geomorphic and stratigraphic analyses within the regional context of the Hellas basin. Terby exhibits ~2-km-thick sequences of layers that consist of repetitive, subhorizontal and laterally continuous beds. The layers are predominantly fine-grained as indicated by their ease of aeolian eros…
Electron microdiffusion in the Saturnian radiation belts: Cassini MIMI/LEMMS observations of energetic electron absorption by the icy moons
Krupp, N.; Woch, J.; Dougherty, M. K. +7 more
Since Saturn orbit insertion (SOI), Cassini has performed numerous crossings of Saturn's inner moons' L shells. The Low-Energy Magnetospheric Measurement System (LEMMS) has detected a large number of microsignatures in its lowest-energy electron channels (20-100 keV) as well as in the MeV energy range. We have catalogued and analyzed more than 70 …
XMM-Newton Observations of the Diffuse X-Ray Background
Covey, K.; Gupta, A.; Galeazzi, M. +1 more
We analyze two XMM-Newton observations toward the high-density, high-latitude, neutral hydrogen cloud MBM 20 and a nearby low-density region that we call the Eridanus hole. MBM 20 lies at a distance between 100 and 200 pc from the Sun, and its density is sufficient to shield about 75% of the foreground emission in the 3/4 keV energy band. The comb…