Search Publications
Rotational Velocities for Early-Type Stars in the Young Large Magellanic Cloud Cluster R136: Further Study of the Relationship Between Rotation Speed and Density in Star-Forming Regions
Cunha, K.; Olsen, K.; Daflon, S. +3 more
We present the results of a study aimed at assessing the distribution of rotation speeds, N(v sin i) among O- and early B-type stars located in R136, a young (t ~ 1-4 Myr) cluster in the Large Magellanic Cloud (LMC) characterized by a stellar density at least three times that of the densest Galactic clusters in which stellar rotational velocities …
A Model for the Total Solar Irradiance Based on Active Region Decay
Charbonneau, P.; Crouch, A. D.; Beaubien, G. +1 more
We present a model for the total solar irradiance. The model takes the observed location, timing, and area of emerging active regions as input and produces a time-evolving size distribution of magnetic structures over the solar surface. We assume that the bright magnetic structures (faculae), which counteract the irradiance deficit caused by sunsp…
On the Solar Origins of Open Magnetic Fields in the Heliosphere
DeRosa, Marc L.; Schrijver, Carolus J.; Rust, David M. +4 more
A combination of heliospheric and solar data was used to identify open magnetic fields stretching from the lower corona to Earth orbit. 35 near-relativistic electron beams detected at the ACE spacecraft "labeled" the heliospheric segments of the open fields. An X-ray flare occurred <20 minutes before injection of the electrons in 25 events. The…
Effects of Solar Active Regions on Meridional Flows
Zhao, Junwei; Kosovichev, Alexander G.; Švanda, Michal
The aim of this Letter is to extend our previous study of the solar-cycle variations of meridional flows and to investigate their latitudinal and longitudinal structure in the subphotospheric layer, especially their variations in magnetic regions. Helioseismology observations indicate that mass flows around active regions are dominated by inflows …
Recent volcano ice interaction and outburst flooding in a Mars polar cap re-entrant
Hovius, Niels; Lea-Cox, Andrew; Turowski, Jens M.
Formation of chasms in the polar ice caps of Mars has been attributed to meltwater outburst floods, but the cause of melting has remained uncertain. In a cap re-entrant enveloping Abalos Colles, west of Casma Boreale in the north polar cap, we have found possible evidence of recent volcano-ice interaction and outburst flooding. In this paper we de…
New active galactic nuclei among the INTEGRAL and SWIFT X-ray sources
Bikmaev, I. F.; Sunyaev, R. A.; Sazonov, S. Yu. +4 more
We present the results of our optical identifications of a set of X-ray sources from the INTEGRAL and SWIFT all-sky surveys. The optical data have been obtained with the 1.5-m Russian-Turkish Telescope (RTT-150). Nine X-ray sources have been identified with active galactic nuclei (AGNs). Two of them are located in the nearby spiral galaxies MCG-01…
The Extended Fe Distribution in the Intracluster Medium and the Implications Regarding AGN Heating
David, Laurence P.; Nulsen, Paul E. J.
We present a systematic analysis of XMM-Newton observations of eight cool-core clusters of galaxies and determine the Fe distribution in the intracluster medium relative to the stellar distribution in the central dominant galaxy (CDG). Our analysis shows that the Fe is significantly more extended than the stellar mass in the CDG in all of the clus…
High-redshift blazar identification for Swift J1656.3-3302
Palazzi, E.; Masetti, N.; Gehrels, N. +9 more
We report on the high-redshift blazar identification of a new gamma-ray source, Swift J1656.3-3302, detected with the BAT imager onboard the Swift satellite and the IBIS instrument on the INTEGRAL satellite. Follow-up optical spectroscopy has allowed us to identify the counterpart as an R∼ 19 mag source that shows broad Lyman-α, Si iv, He ii, C iv…
Helioseismology and the solar cycle
Howe, Rachel
Helioseismic measurements stretching back for about three decades have clearly shown that the acoustic modes are sensitive to solar-cycle changes. 2006 marks the first full 11-year cycle of continuous observations from the Global Oscillation Network Group (GONG), and 10 years of observations with the Michelson Doppler Imager (MDI) aboard the SOHO …
Multi-spacecraft observations of polar coronal plumes
Feng, L.; Wilhelm, K.; Curdt, W. +1 more
Aims:Coronal plumes, along with their structure and rôle in the acceleration of the fast solar wind, are of considerable importance in understanding the physics of the solar atmosphere, in particular, when contrasted with the adjacent plasma, the so-called interplume regions.
Methods: Observations of coronal plumes in a coronal hole were obtai…