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Angular Momentum Evolution of Young Stars in the nearby Scorpius-Centaurus OB Association
Oberst, Thomas E.; Mamajek, Eric E.; Mellon, Samuel N. +1 more
We report the results of a study of archival SuperWASP light curves for stars in Scorpius-Centaurus (Sco-Cen), the nearest OB association. We use SuperWASP time-series photometry to extract rotation periods for 189 candidate members of the Sco-Cen complex and verify that 162 of those are members of the classic Sco-Cen subgroups of Upper Scorpius (…
HST/COS Far-ultraviolet Spectroscopic Analysis of U Geminorum Following a Wide Outburst
Sion, Edward M.; Godon, Patrick; Shara, Michael M. +1 more
We used the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) to obtain a series of four far-ultraviolet (FUV; 915-2148 Å) spectroscopic observations of the prototypical dwarf nova U Geminorum during its cooling following a two-week outburst. Our FUV spectral analysis of the data indicates that the white dwarf (WD) cools from a…
Faint warm debris disks around nearby bright stars explored by AKARI and IRSF
Inutsuka, Shu-ichiro; Onaka, Takashi; Kaneda, Hidehiro +5 more
Context. Debris disks are important observational clues for understanding planetary-system formation process. In particular, faint warm debris disks may be related to late planet formation near 1 au. A systematic search of faint warm debris disks is necessary to reveal terrestrial planet formation.
Aims: Faint warm debris disks show excess em…
Mid-infrared observations of O-type stars: spectral morphology
Bouret, J. -C.; Audard, M.; Lanz, T. +2 more
We present mid-infrared (mid-IR) observations for a sample of 16 O-type stars. The data were acquired with the NASA Spitzer Space Telescope, using the IRS instrument at moderate resolution (R ∼ 600), covering the range of ∼10-37 µm. Our sample includes early, mid and late O supergiants and dwarfs. We explore for the first time their mid-IR s…
Multi-epoch observations with high spatial resolution of multiple T Tauri systems
Ábrahám, Péter; Brandner, Wolfgang; Köhler, Rainer +4 more
Context. In multiple pre-main-sequence systems the lifetime of circumstellar discs appears to be shorter than around single stars, and the actual dissipation process may depend on the binary parameters of the systems.
Aims: We report high spatial resolution observations of multiple T Tauri systems at optical and infrared wavelengths. We deter…
X-ray survey of the North-America and Pelican star-forming complex (NGC 7000/IC 5070)
Damiani, Francesco; Pillitteri, Ignazio; Prisinzano, Loredana
Aims: We present the first extensive X-ray study of the North-America and Pelican star-forming region (NGC 7000/IC 5070), with the aim of finding and characterizing the young population of this cloud.
Methods: X-ray data from Chandra (four pointings) and XMM-Newton (seven pointings) were reduced and source detection algorithm applied to …
Nuclei of dwarf spheroidal galaxies KKs 3 and ESO 269-66 and their counterparts in our Galaxy
Sharina, M. E.; Kniazev, A. Y.; Shimansky, V. V.
We present the analysis of medium-resolution spectra obtained at the Southern African Large Telescope for nuclear globular clusters (GCs) in two dwarf spheroidal galaxies (dSphs). The galaxies have similar star formation histories, but they are situated in completely different environments. ESO 269-66 is a close neighbour of the giant S0 NGC 5128.…
The Unusually High Halo Concentration of the Fossil Group NGC 6482: Evidence for Weak Adiabatic Contraction
Buote, David A.
Although fossil galaxy systems are thought to be very old, and thus should possess above-average halo concentrations, typically fossils have unexceptional concentrations of their masses. We revisit the massive isolated elliptical galaxy/fossil group NGC 6482 for which previous X-ray studies of a modest Chandra observation obtained a very uncertain…
Phase Relations between the Sunspot Numbers and Total Solar Irradiance
Xu, J. C.; Xie, J. L.; Qu, Z. N.
Understanding the effect of sunspot activities on the variations in the total solar irradiance (TSI) is essential for the interpretation of the variability of TSI as well as its reconstruction. Phase relations between the sunspot numbers (SN) and two TSI composite data are investigated. It is found that TSI and SN are positively correlated, and th…
The effect of CO2 on gases trapping in cometary ices
Bar-Nun, A.; Laufer, D.; Ninio Greenberg, A.
Water vapour and CO2 have been detected as the major volatile constituents in the coma of comet 67P/Churyumov-Gerasimenko, by ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft. In this paper, we describe experimental results showing the influence of CO2 trapping in amorphous wat…