Search Publications
Lifting the dust veil from the globular cluster Palomar 2
Chies-Santos, Ana L.; Bonatto, Charles
This work employs high-quality Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) F606W and F814W photometry to correct for the differential reddening affecting the colour-magnitude diagram (CMD) of the poorly studied globular cluster (GC) Palomar 2. Differential reddening is taken into account by assuming that morphological difference…
Extended X-ray emission from the z = 4.26 radio galaxy 4C 63.20
Haardt, Francesco; Ciardi, Benedetta; Ghisellini, Gabriele +5 more
We report on deep Chandra X-ray Telescope imaging observations of 4C 63.20, one of the few known radio galaxies at z > 3.5. The X-ray counterpart is resolved into a core plus two off-nuclear sources that (combined) account for close to 30 per cent of the total X-ray flux. Their morphology and orientation are consistent with a diffuse, lobe-like…
The absolute magnitudes MJ, the binary fraction, and the binary mass ratios of M7-M9.5 dwarfs
Warren, S. J.; Laithwaite, R. C.
We use the large homogeneous sample of late M dwarfs, M7-M9.5, of Ahmed & Warren (2019) matched to Gaia DR2, to measure the relation between absolute magnitude and spectral type, and to infer the multiplicity fraction of the population, and the distribution of mass ratios in the binary systems. Binaries are identified photometrically as overlu…
Possible detection of a new cyclotron feature in 4U 1700-37
Roy, Jayashree; Bhattacharya, Dipankar; Bala, Suman
We present a spectral and timing study of the high-mass X-ray binary transient source 4U 1700-37 using NuSTAR and ASTROSAT/LAXPC. The source is observed in two different flux states. A combined spectral analysis of NuSTAR's focal plane modules A and B shows the possible hint of a cyclotron line feature at ∼16 keV. The line feature is consistently …
Recovering variable stars in large surveys: EAup Algol-type class in the Catalina Survey
Drake, A. J.; Papageorgiou, A.; Catelan, M. +5 more
The discovery and characterization of Algol eclipsing binaries (EAs) provide an opportunity to contribute for a better picture of the structure and evolution of low-mass stars. However, the cadence of most current photometric surveys hinders the detection of EAs since the separation between observations is usually larger than the eclipse(s) durati…
Spectrophotometric characterization of the Philae landing site and surroundings with the Rosetta/OSIRIS cameras
Sierks, H.; Güttler, C.; Barucci, M. A. +5 more
We investigate Abydos, the final landing site of the Philae lander after its eventful landing from the Rosetta spacecraft on comet 67P/Churyumov-Gerasimenko on 2014 November 12. Over 1000 OSIRIS-level 3B images were analysed, which cover the 2014 August-2016 September timeframe, with spatial resolution ranging from 7.6 m pixel-1 to appr…
Search for Zeeman-splitting of OH 6.035 GHz line in the young planetary nebula K 3-35
Hou, L. G.; Gao, X. Y.
Magnetic field could play a role in the formation and early evolution of non-spherical planetary nebulae (PNe). The predominant source of information of the magnetic fields in PNe is the polarization observations of maser emission. To date, distinct and/or possible Zeeman pairs have only been reported towards four PNe by measuring the OH ground-st…
Observations of [OI]63 µm line emission in main-sequence galaxies at z 1.5
Daddi, E.; Valtchanov, I.; Walter, F. +9 more
We present Herschel-PACS spectroscopy of four main-sequence star-forming galaxies at z ~ 1.5. We detect [OI]63 µm line emission in BzK-21000 at z = 1.5213, and measure a line luminosity, $L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$ L⊙. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiat…
VVV-WIT-01: highly obscured classical nova or protostellar collision?
Minniti, D.; Masetti, N.; Krause, M. +18 more
A search of the first Data Release of the VISTA Variables in the Via Lactea (VVV) Survey discovered the exceptionally red transient VVV-WIT-01 (H - Ks = 5.2). It peaked before March 2010, then faded by ∼9.5 mag over the following 2 yr. The 1.6-22 µm spectral energy distribution in March 2010 was well fit by a highly obscured black…
Models of bars - II. Exponential profiles
Evans, N. W.; Sanders, J. L.; McGough, D. P.
We present a new model for galactic bars with exponentially falling major axis luminosity profiles and Gaussian cross-sections. This is based on the linear superposition of Gaussian potential-density pairs with an exponential weight function, using an extension of the method originally introduced by Long & Murali. We compute the density, poten…