Search Publications
The globular cluster mass/low mass X-ray binary correlation: implications for kick velocity distributions from supernovae
Maccarone, T. J.; Kundu, A.; Zepf, S. E. +1 more
Optical and X-ray studies of six nearby galaxies show that the probability a globular cluster will be an X-ray source is consistent with being linearly proportional to its mass. We show that this result is consistent with some recent estimates of the velocity kick distributions for isolated radio pulsars - those which are the sum of two Maxwellian…
Two-phase X-ray burst from GX 3+1 observed by INTEGRAL
Frontera, F.; Lund, N.; in't Zand, J. J. M. +6 more
INTEGRAL detected on August 31, 2004, an unusual thermonuclear X-ray burst from the low-mass X-ray binary GX 3+1. Its duration was 30 min, which is between the normal burst durations for this source (⪉10 s) and the superburst observed in 1998 (several hours). We see emission up to 30 keV energy during the first few seconds of the burst where the b…
Active Region Detection and Verification With the Solar Feature Catalogue
Zharkova, V. V.; Ipson, S.; Zharkov, S. +1 more
We describe the automated extraction of active regions (ARs) or plages from the European Grid of Solar Observations (EGSO) Solar Feature Catalogue using a region-growing technique. In this work, Hα and Ca II K3 solar images from the Meudon Observatory and EUV solar images from the SOHO/EIT instrument were used. For better detection accuracy, the s…
Challenging the Carbon Star Dust Condensation Sequence: Anarchist C Stars
Speck, Angela K.; Corman, Adrian B.; Thompson, Grant D. +1 more
There have been several investigations of the evolution of the mid-infrared (IR) dust features in carbon star spectra based on IRAS LRS data, but these studies are somewhat contradictory. In order to understand these differences in interpretations and to develop an understanding of the carbon star dust sequence, we have reexamined 26 IRAS LRS spec…
Improved oscillator strengths and wavelengths in Hf II, with applications to stellar elemental abundances
Nilsson, H.; Leckrone, D. S.; Lundberg, H. +4 more
Aims. We present new and improved radiative lifetimes for eight levels in Hf I and 18 levels in Hf II, along with oscillator strengths and wavelengths for 195 transitions in Hf II. With these data we determine the abundance of hafnium in two chemically peculiar stars: the hot-Am star HR 3383 and the HgMn star χ Lupi, and discuss the implications o…
A multi-satellite study of accelerated ionospheric ion beams above the polar cap
Balogh, A.; Rème, H.; Grigorenko, E. +7 more
This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5-9 RE. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line p…
Adaptive Optics Imaging of Low-Redshift Damped Lyα Quasar Absorbers
Kulkarni, Varsha P.; Chun, Mark R.; Gharanfoli, Soheila +1 more
We have carried out a high angular resolution near-infrared imaging study of the fields of six quasars with seven strong absorption-line systems at z<0.5, using the Hokupa'a adaptive optics system and the Quick Infrared Camera on the Gemini North telescope. These absorption systems include four classical damped Lyα absorbers (DLAs), two sub-DLA…
Magnetic structure of the solar transition region as observed in various ultraviolet lines emitted at different temperatures
Tu, C. -Y.; Marsch, E.; He, J. -S. +1 more
Aims.The structure of the solar transition region (TR) in a polar coronal hole of the Sun is studied. In particular, the detailed association of the coronal magnetic field (carpet) with the radiance patterns of the TR, when seen in various far ultraviolet (FUV) emission lines, is investigated.
Methods: .A detailed comparison is made of the cor…
The Inner Resonance Ring of NGC 3081. II. Star Formation, Bar Strength, Disk Surface Mass Density, and Mass-to-Light Ratio
Byrd, Gene G.; Freeman, Tarsh; Buta, Ronald J.
We complement our Hubble Space Telescope (HST) observations of the inner ring of the galaxy NGC 3081 using an analytical approach and n-body simulations. We find that a gas cloud inner (r) ring forms under a rotating bar perturbation with very strong azimuthal cloud crowding where the ring crosses the bar major axis. Thus, star formation results n…
FAST TRACK PAPER: The SGR 1806-20 magnetar signature on the Earth's magnetic field
Mandea, M.; Balasis, G.
SGRs denote `soft γ-ray repeaters', a small class of slowly spinning neutron stars with strong magnetic fields. On 2004 December 27, a giant flare was detected from magnetar SGR 1806-20. The initial spike was followed by a hard-X-ray tail persisting for 380 s with a modulation period of 7.56 s. This event has received considerable attention, parti…