Search Publications
Multi-wavelength, spatially resolved modelling of HD 48682's debris disc
Marshall, J. P.; Horner, J.; Marsden, S. C. +1 more
Asteroids and comets (planetesimals) are created in gas- and dust-rich protoplanetary discs. The presence of these planetesimals around main-sequence stars is usually inferred from the detection of excess continuum emission at infrared wavelengths from dust grains produced by destructive processes within these discs. Modelling of the disc structur…
Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies
O'Dea, C. P.; Baum, S. A.; Gallimore, J. F. +2 more
How do active galactic nuclei with low optical luminosities produce powerful radio emission? Recent studies of active galactic nuclei with moderate radio and low optical luminosities (Fanaroff & Riley class I, FR I) searching for broad nuclear emission lines in polarized light, as predicted by some active galactic nucleus unification models, h…
Nondetection of Radio Emissions From Titan Lightning by Cassini RPWS
Gurnett, D. A.; Kurth, W. S.; Fischer, G. +1 more
The Saturn-orbiting Cassini spacecraft completed 126 close Titan flybys from 2004 until 2017. During almost all of them the Cassini Radio and Plasma Wave Science (RPWS) instrument was turned on to search for radio emissions attributed to Titan lightning. Here we report about their nondetection after close inspection of all Titan flybys throughout …
Extragalactic X-ray discrete sources
Zadorozhna L. V.; Tugay A. V.; Shevchenko S. Yu.
Extra-galactic X-ray research with the launch of XMM-Newton has become the forefront of X-ray astronomy. X-ray sources outside our galaxy are the other galaxies - normal galaxies, radio galaxies, quasars, blazars, Seyfert galaxies, as well as extended sources in galaxy clusters - the glow of cluster's halo. X-ray space observatory's equipment reac…
Low optical polarization at the core of the optically thin jet of M87
Merloni, A.; Prieto, M. A.; Acosta-Pulido, J. A. +2 more
We study the optical linear and circular polarization in the optically thin regime of the core and jet of M87. Observations were acquired two days before the Event Horizon Telescope (EHT) campaign in early 2017 April. A high degree (∼20 per cent) of linear polarization (Plin) is detected in the bright jet knots resolved at $\sim 10\,\ma…
Geological characterization of Chandrayaan-2 landing site in the southern high latitudes of the Moon
Harish; Bhatt, Megha; Bhardwaj, Anil +7 more
ISRO's lunar orbiter-lander-rover mission Chandryaan-2 is scheduled to be launched in the mid of 2019. In this contribution, we have carried out detailed geological characterization of the prime landing site (70.9°S, 22.8°E) of the Chandrayaan-2 lander - "Vikram". The proposed landing site is located amidst the nearside lunar highlands at high sou…
Bridging the ultraviolet and optical regions: Transformation equations between GALEX and UBV photometric systems
Bilir, S.; Ak, T.; Yontan, T. +6 more
We derive transformation equations between GALEX and UBV colours by using the reliable data of 556 stars. We present two sets of equations: as a function of (only) luminosity class and as a function of both luminosity class and metallicity. The metallicities are provided from the literature, while the luminosity classes are determined by using the…
2MASS J04435686+3723033 B: A Young Companion at the Substellar Boundary with Potential Membership in the β Pictoris Moving Group
Bowler, Brendan P.; Liu, Michael C.; Phillips, Caprice L. +2 more
We present a detailed characterization of 2MASS J04435750+3723031, a low-mass companion orbiting the young M2 star 2MASS J04435686+3723033 at 7"6 (550 au) with potential membership in the 23 Myr β Pictoris moving group (βPMG). Using near-infrared (NIR) spectroscopy of the companion from IRTF/SpeX, we have found a spectral type of M6 ± 1 and indica…
A systematic study of spiral density waves in the accretion discs of cataclysmic variables
Groot, P. J.; Steeghs, D.; Ruiz-Carmona, R.
Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including cataclysmic variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two decades. We present the results of a systematic study searching for spiral density waves in CVs, and report t…
NLTE C and O abundances in RR lyrae stars
Wallerstein, George; Korotin, Sergey A.; Huang, Wenjin +5 more
The high excitation levels that form the O I and C I lines seen in RR Lyrae stars have long been known not to obey local thermodynamic equilibrium (LTE) statistics. We have observed 21 RR Lyrae and related stars with the Apache Point Observatory echelle spectrograph on the 3.5-m telescope and, for the first time, have derived abundances using non-…