Search Publications
X-ray spectroscopy of the hot gas in the M31 bulge
Wang, Q. Daniel; Liu, Jiren; Li, Zhiyuan +1 more
We present an X-ray spectroscopic study of the nuclear region of the M31 bulge, based on observations of the XMM-Newton Reflection Grating Spectrometers. The obtained high-resolution grating spectra clearly show individual emission lines of highly ionized iron and oxygen, which unambiguously confirm the presence of diffuse hot gas in the bulge, as…
The quest for the Sun's siblings: an exploratory search in the Hipparcos Catalogue
Brown, Anthony G. A.; Portegies Zwart, Simon F.; Bean, Jennifer
We describe the results of a search for the remnants of the Sun's birth cluster among stars in the Hipparcos Catalogue. This search is based on the predicted phase-space distribution of the Sun's siblings from simple simulations of the orbits of the cluster stars in a smooth Galactic potential. For stars within 100 pc, the simulations show that it…
Star formation history of KDG61 and KDG64 from spectroscopy and colour-magnitude diagrams
Makarova, Lidia; Makarov, Dmitry; Koleva, Mina +1 more
A study of two dE/dSph members of the nearby M81 group of galaxies, KDG61 and UGC5442 = KDG64, has been made. Direct Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images and integrated-light spectra of 6-m telescope of Special Astrophysical Observatory of Russian Academy of Sciences have been used for quantitative star formation h…
SAO RAS 6-m telescope spectroscopic observations of globular clusters in nearby galaxies
Chandar, Rupali; Goudfrooij, Paul; Puzia, Thomas H. +2 more
We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in M33 (15 objects), M31 (three), IC10 (four), UGCA86 (four), Holmberg IX (one) and DDO71 (one) obtained at the Special Astrophysical Observatory 6-m telescope. Measurements of Li…
Using the ROSAT catalogue to find counterparts for unidentified objects in the first Fermi/LAT catalogue
Masetti, N.; Landi, R.; Malizia, A. +4 more
There are a total of 1451 gamma-ray emitting objects in the Fermi Large Area Telescope First Source Catalogue. The point source location accuracy of typically a few arcmin has allowed the counterparts for many of these sources to be found at other wavelengths, but even so there are 630 which are described as having no plausible counterpart at 80 p…
Fading of the X-ray flux from the black hole in the NGC 4472 globular cluster RZ 2109
Kundu, Arunav; Zepf, Stephen E.; Maccarone, Thomas J. +1 more
We present the results of new X-ray observations of XMMU 122939.7+075333, the black hole (BH) in the globular cluster RZ 2109 in the Virgo cluster galaxy NGC 4472. A combination of non-detections and marginal detections in several recent Swift and Chandra observations show that the source has varied by at least a factor of 20 in the past 6 yr, and…
H2 reformation in post-shock regions
Kristensen, L. E.; Cuppen, H. M.; Gavardi, E.
H2 formation is an important process in post-shock regions, since H2 is an active participant in the cooling and shielding of the environment. The onset of H2 formation therefore has a strong effect on the temperature and chemical evolution in the post-shock regions. We recently developed a model for H2 …
Application of Double Beltrami states to solar eruptions
Kagan, D.; Mahajan, S. M.
We show that the general class of Double Beltrami (DB) states, which are the lowest energy equilibria of Hall magnetohydrodynamics, can have characteristics similar to those of active regions in the solar corona and is capable of undergoing a catastrophe that can cause a solar eruption, such as a flare or coronal mass ejection (CME). We then show …
Testing PDR models against ISO fine structure line data for extragalactic sources
Barlow, M. J.; Bell, T. A.; Viti, S. +2 more
Far-infrared [CII] 158-µm, [OI] 145-µm and [OI] 63-µm fine structure emission-line fluxes were measured from archival Infrared Space Observatory Long Wavelength Spectrometer spectra of 46 extragalactic sources, with 28 sources providing detections in all three lines. For 12 of the sources, the contribution to the [CII] 158-µ…
Near-infrared/optical identification of five low-luminosity X-ray pulsators
Paul, Biswajit; Wijnands, Rudy; Degenaar, Nathalie +2 more
We present the identification of the most likely near-infrared (NIR)/optical counterparts of five low-luminosity X-ray pulsators (AX J1700.1-4157, AX J1740.1-2847, AX J1749.2-2725, AX J1820.5-1434 and AX J1832.3-0840) which have long pulse periods (>150 s). The X-ray properties of these systems suggest that they are likely members of persistent…