Search Publications
Metal-line system survey: characterizing the low-redshift IGM
Cooksey, Kathy L.; Prochaska, Jason X.
The low-redshift IGM probes the last ten billion years of metal enrichment from galactic feedback processes. We present preliminary results from a survey of intergalactic metal-line absorption systems in archival HST STIS, GHRS, and FUSE spectra of ≈50 z≲2 UV-bright objects. We summarize the detailed analysis of one sightline (PKS1302–102, zQ…
On properties of radio-rich coronal mass ejections
Mittal, Nishant; Sharma, Joginder; Tomar, Vivek +1 more
We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–2006) which produce type II (1–14 MHz) i.e. decametric–hectometric or DH radio burst. These DH CMEs are relatively faster and wider than the normal CMEs. The average speed and apparent width of these CMEs is 1048 km/s and 98°, respectively. Majority (a…
On the possibility of microbiota transfer from Venus to Earth
Wickramasinghe, N. C.; Wickramasinghe, J. T.
The possibility of the clouds of Venus providing habitats for extremophilic microorganisms has been discussed for several decades. We show here that the action of the solar wind leads to erosion of parts of the atmosphere laden with aerosols and putative microorganisms, forming a comet-like tail in the antisolar direction. During inferior conjunct…
Infrared study of infrared carbon stars based on 2MASS, IRAS and ISO SWS data
Chen, Pei-Sheng; Shan, Hong-Guang
For this paper, we collected all infrared carbon stars (IRCSs) known so far from the literature and identified the 2MASS counterparts of all IRCSs. Using 2MASS, IRAS and ISO SWS data, we investigate the infrared properties of IRCSs. We find that the infrared colors and temperatures of IRCSs—not only in the IRAS region but also in the near infrared…
Modeling the emission processes in blazars
Böttcher, Markus
Blazars are the most violent steady/recurrent sources of high-energy gamma-ray emission in the known Universe. They are prominent emitters of electromagnetic radiation throughout the entire electromagnetic spectrum. The observable radiation most likely originates in a relativistic jet oriented at a small angle with respect to the line of sight. Th…
The magnificent seven: magnetic fields and surface temperature distributions
Haberl, Frank
Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name "The Magnificent Seven". Five of the stars exhibit pulsations in their X-ray f…
X-ray observations of ultraluminous X-ray sources
Roberts, Timothy P.
Ultraluminous X-ray sources (ULXs) are amongst the most intriguing of X-ray source classes. Their extreme luminosities—greater than 1039 erg s‑1 in the 0.3–10 keV band alone—suggest either the presence of black holes larger than those regularly encountered in our own Galaxy (the Galactic centre excepted), or sources apparentl…
Resonant Compton upscattering in anomalous X-ray pulsars
Baring, Matthew G.; Harding, Alice K.
A significant new development in the study of Anomalous X-ray Pulsars (AXPs) has been the recent discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper quasi-power-law tails seen in the classic X-ray band in these sources. A prime candidate mechanism f…
Isolated neutron stars: magnetic fields, distances,and spectra
van Kerkwijk, M. H.; Kaplan, D. L.
We present timing measurements, astrometry, and high-resolution spectra of a number of nearby, thermally emitting, isolated neutron stars. We use these to infer magnetic field strengths and distances, but also encounter a number of puzzles. We discuss three specific ones in detail: (i) For RX J0720.4-3125 and RX J1308.6+2127, the characteristic ag…
The trigonometric parallax of the neutron star Geminga
Anderson, Jay; Walter, Frederick M.; Faherty, Jacqueline
We obtained a series of four observations of the isolated neutron star Geminga over an 18 month period using the Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) on the Hubble Space Telescope in order to determine its trigonometric parallax. We find the parallax π=4.0±1.3 mas, corresponding to a distance to Geminga of 250