Search Publications
Probing the nuclear and circumnuclear properties of NGC 6300 using X-ray observations
Naik, Sachindra; Jana, Arghajit; Chatterjee, Arka +3 more
We present the results obtained from a detailed X-ray timing and spectral analysis of the Seyfert 2 galaxy NGC 6300 by using observations from the Suzaku observatory, theChandra X-ray Observatory and the Nuclear Spectroscopic Telescope Array(NuSTAR) mission between 2007 and 2016. We calculate the variance and the rms fractional variability of the …
Evidence of an evolved nature of MWC 349A
Kraus, M.; Arias, M. L.; Cidale, L. S. +1 more
The Galactic emission-line object MWC 349A is one of the brightest radio stars in the sky. The central object is embedded in an almost edge-on oriented Keplerian rotating thick disc that seems to drive a rotating bipolar wind. The dense disc is also the site of hot molecular emission such as the CO bands with its prominent band heads in the near-i…
Near-perihelion activity of comet 67P/Churyumov-Gerasimenko. A first attempt of non-static analysis
Keller, H. U.; Mottola, S.; Hartogh, P. +1 more
The observed rate of water production of comet 67P/Churyumov-Gerasimenko near its perihelion can be approximated by a very steep power function of the heliocentric distance. Widely used thermophysical models based on a static dust layer on top of the icy/refractory matrix are poorly consistent with these observations. We analyse published model re…
A census of young stellar population associated with the Herbig Be star HD 200775
Mathew, Blesson; Manoj, P.; Lee, Chang Won +4 more
The region surrounding the well-known reflection nebula, NGC 7023, illuminated by a Herbig Be star, HD 200775, located in the dark cloud L1174 is studied in this work. Based on the distances and proper motion values from Gaia DR2 of 20 previously known young stellar object (YSO) candidates, we obtained a distance of 335 ± 11 pc to the cloud comple…
On the nature of the soft γ-ray emission in the hard state of the black hole transient GRS 1716-249
Motta, S. E.; Segreto, A.; Casella, P. +9 more
The black hole transient GRS 1716-249 was monitored from the radio to the γ-ray band during its 2016-2017 outburst. This paper focuses on the spectral energy distribution (SED) obtained in 2017 February-March, when GRS 1716-249 was in a bright hard spectral state. The soft γ-ray data collected with the INTEGRAL/SPI telescope show the presence of a…
The observational impact of dust trapping in self-gravitating discs
Cadman, James; Hall, Cassandra; Rice, Ken +2 more
We present a 3D semi-analytical model of self-gravitating discs, and include a prescription for dust trapping in the disc spiral arms. Using Monte Carlo radiative transfer, we produce synthetic ALMA (Atacama Large Millimeter/submillimeter Array) observations of these discs. In doing so, we demonstrate that our model is capable of producing observa…
Resonant capture in quadruple stellar systems
Tremaine, Scott
Some quadruple star systems in the hierarchical 2 + 2 configuration exhibit orbit-orbit resonances between the two compact binaries. We show that the most important resonances occur at period ratios of 1:1, 3:2, and 2:1. We describe the conditions required for capture and show that they can be satisfied at the 3:2 and 2:1 resonances in binaries th…
Predictions of Gaia's prize microlensing events are flawed
McGill, Peter; Everall, Andrew; Boubert, Douglas +1 more
Precision astrometry from the second Gaia data release has allowed astronomers to predict 5787 microlensing events, with 528 of these having maximums within the extended Gaia mission (J2014.5-J2026.5). Future analysis of the Gaiatime-series astrometry of these events will, in some cases, lead to precise gravitational mass measurements of the lens.…
Planetary nebulae with Wolf-Rayet-type central stars - I. The case of the high-excitation NGC 2371
Guerrero, M. A.; Toalá, J. A.; Todt, H. +4 more
We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf-Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morp…
Planetary candidates transiting cool dwarf stars from campaigns 12 to 15 of K2
Bonavera, L.; Schlieder, Joshua E.; Howell, Steve B. +15 more
We analysed the photometry of 20 038 cool stars from campaigns 12, 13, 14, and 15 of the K2 mission in order to detect, characterize, and validate new planetary candidates transiting low-mass stars. We present a catalogue of 25 new periodic transit-like signals in 22 stars, of which we computed the parameters of the stellar host for 19 stars and t…