Search Publications
Period switching in the symbiotic star BX Mon
Formiggini, Liliana; Leibowitz, Elia M.
We report on a detailed analysis of the optical light curve (LC) of the symbiotic system BX Mon, the data of which were gathered from the literature. The LC covers the period from 1889 December to 2009 March, with a gap of no observations between 1940 March and 1972 February. The LC is characterized by strong oscillations of peak-to-peak amplitude…
Optical and mid-infrared observations of the planetary nebula NGC 6781
Guerrero, Martín A.; Ramos-Larios, Gerardo; Phillips, J. P.
Although the planetary nebula NGC 6781 appears to possess an elliptical morphology, its kinematic and emission characteristics are in many ways unusual, and it is possible that it may represent a bipolar source oriented close to the line of sight. We shall present deep imaging of this nebula in [O III]λ5007, Hα and [N II]λ6584, and using broad-ban…
Simple stellar population models including blue stragglers
Deng, Licai; de Grijs, Richard; Kroupa, Pavel +1 more
Observations show that nearly all star clusters and stellar populations contain blue straggler stars (BSs). BSs in a cluster can significantly enhance the integrated spectrum of the host population, preferentially at short wavelengths, and render it much bluer in photometric colours. Current theoretical simple stellar population (SSP) models const…
A pilot study for the SCUBA-2 `All-Sky' Survey
Ivison, R. J.; Hill, T.; Berry, David +31 more
We have carried out a pilot study for the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) ‘All-Sky’ Survey (SASSy), a wide and shallow mapping project at 850 µm, designed to find rare objects, both Galactic and extragalactic. Two distinct sets of exploratory observations were undertaken and used to test the SASSy approach and data-redu…
The low-luminosity active galactic nucleus in the centre of the Galaxy
Contini, M.
The observations of far-infrared line and continuum spectra throughout the Galactic Centre and in some regions of the disc are analysed in order to determine the physical conditions (densities, shock velocities, radiation parameters etc.) and the relative abundances of some elements (C, N and O). Consistent model calculations of the line and conti…
Dark matter-rich early-type galaxies in the CASSOWARY 5 strong lensing system
Grillo, C.; Christensen, L.
We study the strong gravitational lensing system number 5 identified by the CAmbridge Sloan Survey Of Wide ARcs in the skY (CASSOWARY). In this system, a source at redshift 1.069 is lensed into four detected images by two early-type galaxies at redshift 0.388. The average projected angular distance of the multiple images from the primary lens is 1…
Importance of far-infrared mapping in a spiral galaxy: AKARI observation of M81
Sun, Ai-Lei; Hirashita, Hiroyuki
The importance of the far-infrared (FIR) mapping is demonstrated for a face-on spiral galaxy, M81, by analysing its imaging data at 65, 90 and ? taken by AKARI. The basic products are the dust temperature map, the dust optical depth map and the colour-colour diagram. The main features are as follows. (i) The dust temperature derived from the total…
The morphology-density relation of galaxies around MACS J0717.5+3745
Ebeling, H.; Ma, C. -J.
We use an 18 × 9 arcmin2 mosaic of HST/ACS images covering the entire large-scale structure around the X-ray luminous cluster MACSJ0717.5+3745 (z= 0.545) to study the morphology of galaxies at the cluster redshift. We find the global fraction of morphological types of galaxies to be consistent with results in the literature. In addition…
The nature of the Na I D-lines in the Red Rectangle
York, Donald G.; Bjorkman, J. E.; Federman, S. R. +6 more
In this paper we examine the profiles of the complex Na I D-lines in the Red Rectangle. The spectra were acquired with the Astrophysical Research Consortium Echelle Spectrograph (ARCES) echelle spectrograph (R= 38 000) on the 3.5-m telescope at the Apache Point Observatory. Additional spectra taken with Space Telescope Imaging Spectrograph were ac…
Searching for an intermediate-mass black hole in the blue compact dwarf galaxy MRK 996
Georgakakis, A.; Tsamis, Y. G.; Aloisi, A. +1 more
The possibility is explored that accretion on an intermediate-mass black hole contributes to the ionization of the interstellar medium of the compact blue dwarf galaxy MRK 996. Chandra observations set tight upper limits (99.7 per cent confidence level) in both the X-ray luminosity of the posited active galactic nucleus (AGN), LX(2-10 k…