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Properties and geoeffectiveness of magnetic clouds in the rising, maximum and early declining phases of solar cycle 23
Schwenn, R.; Bothmer, V.; Koskinen, H. E. J. +1 more
The magnetic structure and geomagnetic response of 73 magnetic clouds (MC) observed by the WIND and ACE satellites in solar cycle 23 are examined. The results have been compared with the surveys from the previous solar cycles. The preselected candidate MC events were investigated using the minimum variance analysis to determine if they have a flux…
High-Ionization Emission in Metal-deficient Blue Compact Dwarf Galaxies
Thuan, Trinh X.; Izotov, Yuri I.
Primordial stars are expected to be very massive and hot, producing copious amounts of hard ionizing radiation. The best place to study hard ionizing radiation in the local universe is in very metal-deficient blue compact dwarf (BCD) galaxies. We have carried out a MMT spectroscopic search for [Ne V] λ3426 (ionization potential of 7.1 ryd), [Fe V]…
Galaxy Morphologies in the Hubble Ultra Deep Field: Dominance of Linear Structures at the Detection Limit
Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Rubin, Douglas S. +1 more
Galaxies in the Hubble Ultra Deep Field (UDF) larger than 10 pixels (0.3") have been classified according to morphology, and their photometric properties are presented. There are 269 spiral, 100 elliptical, 114 chain, 126 double-clump, 97 tadpole, and 178 clump-cluster galaxies. We also cataloged 30 B-band and 13 V-band dropouts and calculated the…
How to Channel Photospheric Oscillations into the Corona
Erdélyi, R.; De Pontieu, B.; De Moortel, I.
There are now many observations of waves in the solar corona with periods around 5 minutes. The source of these waves is uncertain, although global p-modes in the photosphere are an obvious candidate, given the similarity of the dominant periods. However, p-modes are traditionally considered evanescent in the upper photosphere, and it has been unc…
The primordial binary population. I. A near-infrared adaptive optics search for close visual companions to A star members of Scorpius OB2
Kaper, L.; Brown, A. G. A.; Zinnecker, H. +2 more
We present the results of a near-infrared adaptive optics survey with the aim to detect close companions to Hipparcos members in the three subgroups of the nearby OB association Sco OB2: Upper Scorpius (US), Upper Centaurus Lupus (UCL) and Lower Centaurus Crux (LCC). We have targeted 199 A-type and late B-type stars in the KS band, and …
Electric current and magnetic field geometry in flapping magnetotail current sheets
Sauvaud, J. -A.; Balogh, A.; Zhang, T. L. +11 more
Using four-point magnetic field measurements by the Cluster spacecraft, we statistically analyze the magnetic field and electric current configurations during rapid crossings of the current sheet observed in July-October 2001 at geocentric distances of 19 RE. The database includes 78 crossings, specially selected to apply multi-point da…
Cepheid Calibrations from the Hubble Space Telescope of the Luminosity of Two Recent Type Ia Supernovae and a Redetermination of the Hubble Constant
Filippenko, Alexei V.; Riess, Adam G.; Challis, Peter M. +6 more
We report observations of two nearby Type Ia supernovae (SNe Ia) for which observations of Cepheid variables in the host galaxies have been obtained with the Hubble Space Telescope: SN 1994ae in NGC 3370 and SN 1998aq in NGC 3982. For NCG 3370, we used the Advanced Camera for Surveys to observe 64 Cepheids that yield a distance of 29 Mpc, the fart…
The Hubble Deep Field North SCUBA Super-map - III. Optical and near-infrared properties of submillimetre galaxies
Dickinson, Mark; Mobasher, Bahram; Pope, Alexandra +3 more
We present a new submillimetre (submm) super-map in the Hubble Deep Field North (HDF-N) region (Great Observatories Origins Deep Survey North, GOODS-N, field), containing 40 statistically robust sources at 850µm. This map contains additional data, and several new sources, including one of the brightest blank-sky extragalactic submm sources e…
Release of volatiles from a possible cryovolcano from near-infrared imaging of Titan
Rodriguez, S.; Sotin, C.; Brown, R. H. +23 more
Titan is the only satellite in our Solar System with a dense atmosphere. The surface pressure is 1.5bar (ref. 1) and, similar to the Earth, N2 is the main component of the atmosphere. Methane is the second most important component, but it is photodissociated on a timescale of 107years (ref. 3). This short timescale has led to…
Multiphase High-Velocity Clouds toward HE 0226-4110 and PG 0953+414
Tripp, Todd M.; Sembach, Kenneth R.; Savage, Blair D. +3 more
We study the physical conditions, elemental abundances, and kinematics of the high-velocity clouds (HVCs) along the sight lines toward active galaxies HE 0226-4110 and PG 0953+414 using Hubble Space Telescope Space Telescope Imaging Spectrograph and Far Ultraviolet Spectroscopic Explorer data. No 21 cm H I emission is detected in these clouds, but…