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The G305 star-forming complex: the central star clusters Danks 1 and Danks 2
Kudritzki, Rolf-Peter; Figer, Donald F.; Clark, J. S. +7 more
The G305 H II complex (G305.4+0.1) is one of the most massive star-forming structures yet identified within the Galaxy. It is host to many massive stars at all stages of formation and evolution, from embedded molecular cores to post-main-sequence stars. Here, we present a detailed near-infrared analysis of the two central star clusters Danks 1 and…
Lyα Dominance of the Classical T Tauri Far-ultraviolet Radiation Field
Herczeg, Gregory J.; Brown, Alexander; France, Kevin +6 more
Far-ultraviolet (FUV) radiation plays an important role in determining chemical abundances in protoplanetary disks. H I Lyman α (Lyα) is suspected to be the dominant component of the FUV emission from Classical T Tauri Stars (CTTSs), but is difficult to measure directly due to circumstellar and interstellar H I absorption. To better characterize t…
Cyclic loss of open solar flux since 1868: The link to heliospheric current sheet tilt and implications for the Maunder Minimum
Owens, M. J.; Lockwood, M.
Open solar flux (OSF) variations can be described by the imbalance between source and loss terms. We use spacecraft and geomagnetic observations of OSF from 1868 to present and assume the OSF source, S, varies with the observed sunspot number, R. Computing the required fractional OSF loss, χ, reveals a clear solar cycle variation, in approximate p…
The first in situ observation of Kelvin-Helmholtz waves at high-latitude magnetopause during strongly dawnward interplanetary magnetic field conditions
ViñAs, A. F.; Goldstein, M. L.; Wang, Y. +3 more
We report the first in situ observation of high-latitude magnetopause (near the northern duskward cusp) Kelvin-Helmholtz waves (KHW) by Cluster on January 12, 2003, under strongly dawnward interplanetary magnetic field (IMF) conditions. The fluctuations unstable to Kelvin-Helmholtz instability (KHI) are found to propagate mostly tailward, i.e., al…
The Infrared Eye of the Wide-Field Camera 3 on the Hubble Space Telescope Reveals Multiple Main Sequences of Very Low Mass Stars in NGC 2808
Anderson, J.; Milone, A. P.; Marino, A. F. +9 more
We use images taken with the infrared channel of the Wide Field Camera 3 on the Hubble Space Telescope to study the multiple main sequences (MSs) of NGC 2808. Below the turnoff, the red, the middle, and the blue MS, previously detected from visual-band photometry, are visible over an interval of about 3.5 F160W magnitudes. The three MSs merge toge…
Investigation of Dual Active Nuclei, Outflows, Shock-heated Gas, and Young Star Clusters in Markarian 266
Sturm, E.; Veilleux, S.; Sanders, D. B. +24 more
Results of observations with the Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes are presented for the luminous infrared galaxy (LIRG) merger Markarian 266. The SW (Seyfert 2) and NE (LINER) nuclei reside in galaxies with Hubble types SBb (pec) and S0/a (pec), respectively. Both companions are more luminous than L* galaxies and th…
A newly discovered young massive star cluster at the far end of the Galactic Bar
Figer, Donald F.; Davies, Ben; Najarro, Francisco +4 more
We present a near-infrared study of the candidate star cluster Mercer 81, located at the centre of the G338.4+0.1 H II region and close to the TeV gamma-ray source HESS 1640-465. Using Hubble Space Telescope/NICMOS imaging and VLT/ISAAC spectroscopy, we have detected a compact and highly reddened cluster of stars, although the bright stars in the …
Time Delays in Quasi-periodic Pulsations Observed during the X2.2 Solar Flare on 2011 February 15
Schmutz, W.; Zhukov, A. N.; Berghmans, D. +10 more
We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on timescale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager channels in t…
Broad-band study of hard X-ray-selected absorbed active galactic nuclei
de Rosa, A.; Ubertini, P.; Landi, R. +6 more
In this paper we report on the broad-band X-ray properties of a complete sample of absorbed Seyfert galaxies hard X-ray selected with INTEGRAL. Our sample is composed of 33 sources, of which 15 are newly discovered active galactic nuclei (AGN) above 20 keV (IGR sources), while 18 are already known type 2 AGN ('known'). For 17 sources (15 IGR + 2 '…
Assessing the long-term variability of Venus winds at cloud level from VIRTIS-Venus Express
Hueso, R.; Sánchez-Lavega, A.; Peralta, J.
The Venus Express (VEX) mission has been in orbit to Venus for more than 4 years now. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet that can be used to sample the atmosphere at different altitude…