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Revision of Solar Spicule Classification
Liu, Y.; Su, J. T.; Wang, J. X. +4 more
Solar spicules are the fundamental magnetic structures in the chromosphere and may play a key role in channeling the chromosphere and corona. Recently, it was suggested by De Pontieu et al. that there were two types of spicules with very different dynamic properties, which were detected by the space-time plot technique in the Ca II H line (3968 Å)…
Clustering Properties of BzK-selected Galaxies in GOODS-N: Environmental Quenching and Triggering of Star Formation at z ~ 2
Dickinson, Mark; Grogin, Norman A.; Yan, Chi-Hung +19 more
Using a sample of BzK-selected galaxies at z ~ 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M *), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs),…
Automatically Detecting and Tracking Coronal Mass Ejections. I. Separation of Dynamic and Quiescent Components in Coronagraph Images
Morgan, Huw; Habbal, Shadia Rifai; Byrne, Jason P.
Automated techniques for detecting and tracking coronal mass ejections (CMEs) in coronagraph data are of ever increasing importance for space weather monitoring and forecasting. They serve to remove the biases and tedium of human interpretation, and provide the robust analysis necessary for statistical studies across large numbers of observations.…
Broad-line Region Physical Conditions in Extreme Population A Quasars: A Method to Estimate Central Black Hole Mass at High Redshift
Sulentic, Jack W.; Marziani, Paola; Negrete, C. Alenka +1 more
We describe a method for estimating physical conditions in the broad-line region (BLR) for a significant subsample of Seyfert 1 nuclei and quasars. Several diagnostic ratios based on intermediate (Al III λ1860, Si III] λ1892) and high (C IV λ1549, Si IV λ1397) ionization lines in the UV spectra of quasars are used to constrain density, ionization,…
Unmasking the Supernova Impostors
Kochanek, C. S.; Stanek, K. Z.; Szczygieł, D. M.
The canonical picture of a supernova impostor is a short (~months) -11 <~ MV <~ -14 optical transient from a massive (M * >~ 40 M ⊙) star during which the star ejects a dense shell of material. Dust formed in the ejecta then obscures the star. In this picture, the geometric expansion of the shell leads to …
SX Phoenicis period-luminosity relations and the blue straggler connection
Cohen, Roger E.; Sarajedini, Ata
This study is aimed at investigating the period-luminosity relation of SX Phoenicis (SX Phe) pulsators in Galactic globular clusters (GGCs) and Local Group dwarf galaxies. We verify isochrone-fitting distances of 46 GGCs by fitting their main sequences to a carefully chosen set of nearby, unevolved subdwarfs. We find that the difference between cl…
The dispersal of pyroclasts from ancient explosive volcanoes on Mars: Implications for the friable layered deposits
Head, James W.; Forget, François; Madeleine, Jean-Baptiste +2 more
A number of voluminous, fine-grained, friable deposits have been mapped on Mars. The modes of origin for these deposits are debated. The feasibility for an origin by volcanic airfall for the friable deposits is tested using a global circulation model to simulate the dispersal of pyroclasts from candidate source volcanoes near each deposit. It is c…
The Optically Unbiased GRB Host (TOUGH) Survey. V. VLT/X-shooter Emission-line Redshifts for Swift GRBs at z ~ 2
Hjorth, Jens; Fynbo, Johan P. U.; Milvang-Jensen, Bo +7 more
We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift γ-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow…
The Herschel Exploitation of Local Galaxy Andromeda (HELGA). I. Global far-infrared and sub-mm morphology
Blommaert, J. A. D. L.; Boquien, M.; Roussel, H. +30 more
Context. We have obtained Herschel images at five wavelengths from 100 to 500 µm of a ~5.5 × 2.5 degree area centred on the local galaxy M 31 (Andromeda), our nearest neighbour spiral galaxy, as part of the Herschel guaranteed time project "HELGA". The main goals of HELGA are to study the characteristics of the extended dust emission, focusi…
First spectro-interferometric survey of Be stars. I. Observations and constraints on the disk geometry and kinematics
Hofmann, K. -H.; Meilland, A.; Millour, F. +5 more
Context. Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared-excess and emission lines. The phenomena involved in the disk formation still remain highly debated.
Aims: To progress in the understanding of the physical process or processes responsible for the m…