Search Publications
Convection and rotation boosted prescription of magnetic braking: application to the formation of extremely low-mass white dwarfs
Kepler, S. O.; Soethe, L. T. T.
Extremely low-mass white dwarfs (ELM WDs) are the result of binary evolution in which a low-mass donor star is stripped by its companion leaving behind a helium-core white dwarf (WD). We explore the formation of ELM WDs in binary systems considering the Convection And Rotation Boosted magnetic braking treatment. Our evolutionary sequences were cal…
Long-term X-ray observations of seyfert 1 galaxy ark 120: on the origin of soft-excess
Chatterjee, Arka; Nandi, Prantik; Chakrabarti, Sandip K. +1 more
We present the long-term X-ray spectral and temporal analysis of a 'bare-type AGN' Ark 120. We consider the observations from XMM-Newton, Suzaku, Swift, and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of sever…
Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - XII. A sample of systems with K2 photometry
Kambe, E.; Maehara, H.; Espinoza, N. +10 more
We present results of the analysis of light and radial velocity (RV) curves of eight detached eclipsing binaries observed by the All-Sky Automated Survey, which we have followed up with high-resolution spectroscopy, and were later observed by the Keplersatellite as part of the K2mission. The RV measurements came from spectra obtained with OAO-188/…
Hot planets around cool stars - two short-period mini-Neptunes transiting the late K-dwarf TOI-1260
Fridlund, M.; Guenther, E. W.; Barragán, O. +56 more
We present the discovery and characterization of two sub-Neptunes in close orbits, as well as a tentative outer planet of a similar size, orbiting TOI-1260 - a low metallicity K6 V dwarf star. Photometry from Transiting Exoplanet Survey Satellite(TESS) yields radii of Rb = 2.33 ± 0.10 and Rc = 2.82 ± 0.15 R⊕, and p…
Identification of new classical Ae stars in the Galaxy using LAMOST DR5
Arun, R.; Mathew, Blesson; Kartha, Sreeja S. +6 more
We report the first systematic study to identify and characterize a sample of classical Ae stars in the Galaxy. The spectra of these stars were retrieved from the A-star catalogue using the Large sky Area Multi-Object fibre Spectroscopic Telescope (LAMOST) survey. We identified the emission-line stars in this catalogue from which 159 are confirmed…
Proper motions of OB stars in the far Carina Arm
Monguió, M.; Wright, N. J.; Drew, J. E.
In large-scale maps of the Galactic disc, the Carina Arm stands out as a clear spiral feature, hosting prominent star clusters and associations rich in massive stars. We study the proper motions of 4199 O and early B most likely in the far Carina Arm, at distances mainly in excess of 4 kpc from the Sun, within the sky region, 282° < ℓ < 294°…
New observations of NGC 1624-2 reveal a complex magnetospheric structure and underlying surface magnetic geometry
Wade, G. A.; Fullerton, A. W.; Shultz, M. E. +5 more
NGC 1624-2 is the most strongly magnetized O-type star known. Previous spectroscopic observations of this object in the ultraviolet provided evidence that it hosts a large and dense circumstellar magnetosphere. Follow-up observations obtained with the Hubble Space Telescope not only confirm that previous inference, but also suggest that NGC 1624-2…
Giant star-forming complexes in high-z main-sequence galaxy analogues: the internal structure of clumps in DYNAMO galaxies
Glazebrook, Karl; Lenkić, Laura; Bolatto, Alberto D. +4 more
To indirectly study the internal structure of giant clumps in main sequence galaxies at z ~ 1-3, we target very turbulent and gas-rich local analogues from the DYNAMO sample with the Hubble Space Telescope, over a wavelength range of ~200-480 nm. We present a catalogue of 58 clumps identified in six DYNAMO galaxies, including the WFC3/UVIS F225W, …
Optical spectroscopy of Galactic field classical Be stars
Mathew, Blesson; Paul, K. T.; Subramaniam, Annapurni +3 more
In this study, we analyse the emission lines of different species present in 118 Galactic field classical Be stars in the wavelength range of 3800-9000 Å. We re-estimated the extinction parameter (AV) for our sample stars using the newly available data from Gaia DR2 and suggest that it is important to consider AV while measur…
A principal component analysis of polycyclic aromatic hydrocarbon emission in NGC 2023
Cami, Jan; Peeters, Els; Sidhu, Ameek +1 more
We use the measured fluxes of polycyclic aromatic hydrocarbon (PAH) emission features at 6.2, 7.7, 8.6, 11.0, and 11.2 µm in the reflection nebula NGC 2023 to carry out a principal component analysis (PCA) as a means to study previously reported variations in the PAH emission. We find that almost all of the variations (99 per cent) can be ex…