Search Publications
High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements
Ilyin, I.; Tautvaišienė, G.; Cohen, J. G. +4 more
The main atmospheric parameters and abundances of the iron-group elements (vanadium, chromium, iron, cobalt and nickel) are determined for 62 red giant `clump' stars revealed in the Galactic field by the Hipparcos orbiting observatory. The stars form a homogeneous sample with the mean value of temperature Teff = 4750 +/- 160K, of surfac…
Mapping and spectroscopy of the planetary nebula NGC 7009 in the visual and infrared
Ramos-Larios, G.; Phillips, J. P.; Cuesta, L. C.
NGC 7009 is a fascinating example of a high-excitation, elliptical planetary nebula (PN) containing circumnebular rings, and FLIERs and jets along the major axis. We present visual spectroscopy along multiple position angles through the nucleus, taken with the Observatorio Astronomico Nacional (Mexico); mid-infrared (MIR) spectroscopy and imaging …
Observations from Hinode/EIS of intensity oscillations above a bright point: signature of the leakage of acoustic oscillations in the inner corona
Srivastava, A. K.; Dwivedi, B. N.
We study the intensity oscillations in the upper chromosphere/transition region (TR) and corona, above a bright point (BP) in the solar atmosphere. We analyse the time series of HeII 256 Å, FeXII 195 Å and FeXV 284 Å, observed in a 40-arcsec slot close to the centre of the Sun above the BP by the extreme ultraviolet (EUV) imaging spectrometer (EIS…
XMM-Newton observations of unidentified INTEGRAL/IBIS sources
Bird, A. J.; Fiocchi, M.; Malizia, A. +4 more
About 30 per cent of the sources in the fourth INTEGRAL/IBIS catalogue are unidentified in that they lack an optical counterpart. To be able to classify them, X-ray observations are of crucial importance as they can place tighter constraints on the high-energy error box, which is usually of the order of a few arcminutes, and allow their broad-band…
Spitzer mid-infrared observations of seven bipolar planetary nebulae
Ramos-Larios, G.; Phillips, J. P.
We have investigated the mid-infrared (MIR) and visual structures of seven bipolar planetary nebulae (BPNe), using imaging and spectroscopy acquired using the Spitzer Space Telescope (SST), and the Observatorio Astronomico Nacional in Mexico. The results show that the sources are more extended towards longer MIR wavelengths, as well as having high…
An AzTEC 1.1-mm survey for ULIRGs in the field of the Galaxy Cluster MS0451.6-0305
Ivison, R. J.; Yun, M. S.; Smail, Ian +17 more
We have undertaken a deep (σ ~ 1.1 mJy) 1.1-mm survey of the z = 0.54 cluster MS0451.6-0305 using the AzTEC camera on the James Clerk Maxwell Telescope. We detect 36 sources with signal-to-noise ratio (S/N) >= 3.5 in the central 0.10 deg2 and present the AzTEC map, catalogue and number counts. We identify counterparts to 18 sources (…
Does the X-ray emission of the luminous quasar RBS 1124 originate in a mildly relativistic outflowing corona?
Bianchi, S.; Vignali, C.; Piconcelli, E. +2 more
We have observed the luminous (L2-10keV ~= 6 × 1044 ergs-1) radio-quiet quasar RBS 1124 (z = 0.208) with Suzaku. We report the detection of a moderately broad iron (Fe) line and of a weak soft X-ray excess. The X-ray data are very well described by a simple model comprising a power-law X-ray continuum plus its refl…
In-depth studies of the NGC253 ULXs with XMM-Newton: remarkable variability in ULX1, and evidence for extended coronae
Barnard, R.
We examined the variability of three ultraluminous X-ray sources (ULXs) in the 2003, 110ks XMM-Newton observation of NGC253. Remarkably, we discovered ULX1 to be three times more variable than ULX2 in the 0.3-10 keV band, even though ULX2 is brighter. Indeed, ULX1 exhibits a power density spectrum that is consistent with the canonical high state o…
Associated spectral and temporal state transition of the bright ULXNGC1313 X-1
Rao, A. R.; Misra, R.; Dewangan, G. C. +1 more
Stellar mass black hole X-ray binaries exhibit X-ray spectral states which also have distinct and characteristic temporal properties. These states are believed to correspond to different accretion disc geometries. We present analysis of two XMM-Newton observations of the ultra-luminous X-ray source (ULX)NGC1313 X-1, which reveal that the system wa…
XMM-Newton and Swift observations prove GRB090709A to be a distant, standard, long GRB
Tiengo, A.; de Luca, A.; Götz, D. +4 more
GRB090709A is a long gamma-ray burst (GRB) discovered by Swift, featuring a bright X-ray afterglow as well as a faint infrared transient with very red and peculiar colours. The burst attracted a large interest because of a possible quasi-periodicity at P = 8.1s in the prompt emission, suggesting that it could have a different origin with respect t…