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Nitrogen line spectroscopy in O-stars. III. The earliest O-stars
Puls, J.; Najarro, F.; Massey, P. +1 more
Context. The classification scheme proposed by Walborn et al. (2002, AJ, 123, 2754), based primarily on the relative strengths of the N ivλ4058 and N iiiλ4640 emission lines, has been used in a variety of studies to spectroscopically classify early O-type stars. Owing to the lack of a solid theoretical basis, this scheme has not yet been universal…
Magnetic Topology of Active Regions and Coronal Holes: Implications for Coronal Outflows and the Solar Wind
Mandrini, C. H.; van Driel-Gesztelyi, L.; Culhane, J. L. +8 more
During 2 - 18 January 2008 a pair of low-latitude opposite-polarity coronal holes (CHs) were observed on the Sun with two active regions (ARs) and the heliospheric plasma sheet located between them. We use the Hinode/EUV Imaging Spectrometer (EIS) to locate AR-related outflows and measure their velocities. Solar-Terrestrial Relations Observatory (…
On Dark Peaks and Missing Mass: A Weak-lensing Mass Reconstruction of the Merging Cluster System A520
Bradač, Maruša; Massey, Richard; Gonzalez, Anthony H. +4 more
Merging clusters of galaxies are unique in their power to directly probe and place limits on the self-interaction cross-section of dark matter. Detailed observations of several merging clusters have shown the intracluster gas to be displaced from the centroids of dark matter and galaxy density by ram pressure, while the latter components are spati…
Hydrogen peroxide on Mars: Observations, interpretation and future plans
Encrenaz, T.; Atreya, S. K.; Greathouse, T. K. +1 more
Ever since the Viking mass spectrometer failed to detect organics on the surface of Mars in 1976 (Biemann et al., 1976), hydrogen peroxide (H2O2) has been suggested as a possible oxidizer of the Martian surface (Oyama and Berdahl, 1977). However, the search for H2O2 on Mars was unsuccessful for three dec…
Are the strengths of solar cycles determined by converging flows towards the activity belts?
Schüssler, M.; Cameron, R. H.
It is proposed that the observed near-surface inflows towards the active regions and sunspot zones provide a nonlinear feedback mechanism that limits the amplitude of a Babcock-Leighton-type solar dynamo and determines the variation of the cycle strength. This hypothesis is tested with surface flux transport simulations including converging latitu…
Characterizing Transition Temperature Gas in the Galactic Corona
Savage, Blair D.; Fox, Andrew J.; Wakker, Bart P. +2 more
We present a study of the properties of the transition temperature (T ~ 105 K) gas in the Milky Way corona, based on the measurements of O VI, N V, C IV, Si IV, and Fe III absorption lines seen in the far-ultraviolet spectra of 58 sight lines to extragalactic targets, obtained with the Far-Ultraviolet Spectroscopic Explorer and the Spac…
Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk
Lutz, D.; Genzel, R.; Poglitsch, A. +13 more
We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J upper = 14-30 (E upper/kB = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transiti…
Signatures of minor mergers in Milky Way like disc kinematics: ringing revisited
Gómez, Facundo A.; Minchev, Ivan; O'Shea, Brian W. +2 more
By means of N-body simulations, we study the response of a galactic disc to a minor merger event. We find that non-self-gravitating, spiral-like features are induced in the thick disc. As we have shown in a previous work, this 'ringing' also leaves an imprint in velocity space (the u-v plane) in small spatial regions, such as the solar neighbourho…
The dust energy balance in the edge-on spiral galaxy NGC 4565
Gordon, Karl D.; De Looze, Ilse; Baes, Maarten +20 more
We combine new dust continuum observations of the edge-on spiral galaxy NGC 4565 in all Herschel/Spectral and Photometric Imaging Receiver (250, 350 and 500 µm) wavebands, obtained as part of the Herschel Reference Survey, and a large set of ancillary data (Spitzer, Sloan Digital Sky Survey, Galaxy Evolution Explorer) to analyse its dust ene…
The Disk-wind-Jet Connection in the Black Hole H 1743-322
Fabian, A. C.; Miller, J. M.; Reynolds, C. S. +6 more
X-ray disk winds are detected in spectrally soft, disk-dominated phases of stellar-mass black hole outbursts. In contrast, compact, steady, relativistic jets are detected in spectrally hard states that are dominated by non-thermal X-ray emission. Although these distinctive outflows appear to be almost mutually exclusive, it is possible that a disk…