Search Publications
Photometric analysis of three totally eclipsing W UMa stars with increasing periods: TYC 3700-1384-1, V1511 Her, and V1179 Her
Broens, Eric
The first multicolour light-curve models and period studies for the totally eclipsing W UMa stars TYC 3700-1384-1, V1511 Her, and V1179 Her are presented. All three stars are A-subtype W UMa stars of spectral type F. The light-curve solutions show that TYC 3700-1384-1 has a moderately low mass ratio of q = 0.182 ± 0.001 and a degree of overcontact…
Double trouble: Gaia reveals (proto)planetary systems that may experience more than one dense star-forming environment
Parker, Richard J.; Schoettler, Christina
Planetary systems appear to form contemporaneously around young stars within young star-forming regions. Within these environments, the chances of survival, as well as the long-term evolution of these systems, are influenced by factors such as dynamical interactions with other stars and photoevaporation from massive stars. These interactions can a…
Shape, colour, and distance in weak gravitational flexion
Goldberg, David M.; Fabritius, Joseph M., II; Arena, Evan J.
Canonically, elliptical galaxies might be expected to have a perfect rotational symmetry, making them ideal targets for flexion studies - however, this assumption has not been tested. We have undertaken an analysis of low- and high-redshift galaxy catalogues of known morphological type with a new gravitational lensing code, Lenser. Using colour me…
Compact planetary nebulae MaC 2-1 and Sp 4-1: photoionization models and dust characteristics
Mondal, Soumen; Das, Ramkrishna; Bandyopadhyay, Rahul
We study the characteristics of the planetary nebulae (PNe) MaC 2-1 and Sp 4-1. We use our optical spectra taken with the 2 m Himalayan Chandra Telescope, Spitzer mid-infrared (mid-IR) spectra, HST images, and IR photometric data. These PNe have not previously been individually studied in detail. Both are in the low- to moderate-excitation class. …
Studying the interstellar medium to look for relics of triggered star formation among stellar clusters
Granada, A.; Paron, S.; Areal, M. B.
Evidence of triggered star formation at large spatial scales involving stellar clusters is scarce. We investigate a Galactic region (l = 130${_{.}^{\circ}}$0, b = 0${_{.}^{\circ}}$35) populated by several open stellar clusters that according to the last Gaia data release, are located at a distance of about 2.9 kpc. By analysing the interstellar me…
Search for LBVs in the Local Volume galaxies: study of four stars in NGC 4449
Vinokurov, A.; Solovyeva, Y.; Atapin, K. +8 more
We continue to search for LBV stars in galaxies outside the Local Group. In this work, we have investigated four luminous stars in NGC 4449. Multiple spectral observations carried out for J122810.94+440540.6, J122811.70+440550.9, and J122809.72+440514.8 revealed the emission features in their spectra that are characteristic of LBVs. Photometry sho…
Physical modelling of the circumstellar material in the early-type active binary HH Carinae
Bakış, V.; Eker, Z.; Nitschelm, C. +2 more
High-resolution spectra ( $R\sim 48\, 000$ ) of the massive binary system HH Carinae have been analysed. Precise absolute parameters were derived from a simultaneous solution of the radial velocities and the light curves. The primary component is found to be an O9-type main-sequence star with a temperature of 33 500 K, while the secondary componen…
Rotational excitation of highly excited H2O by H2
Żóltowski, Michal; Lique, François; Karska, Agata +1 more
Water is a key molecule for interstellar chemistry. Observations with Herschel telescope show significant population of very high rotational transitions (j ≳ 8) in young stellar objects, indicating significant amounts of water in hot (T ≳ 1500 K) and dense (n ≳ 106 cm-3) gas. Non-local thermodynamic equilibrium (LTE) modellin…
Optical counterparts of ULXs in two dwarf galaxies: NGC 4861 and NGC 4449
Ozdogan Ela, M.; Akyuz, A.; Aksaker, N. +7 more
We present the results of a search for optical candidates of ultraluminous X-ray sources (ULXs) in two dwarf galaxies, NGC 4861 and NGC 4449, using Hubble Space Telescope (HST) archival data. With precise astrometry, we confirm that NGC 4861 X1 is associated with an H II complex and we conclude that NGC 4861 X2 resides in a young star group of mas…
A Gemini-NIFS view of the merger remnant NGC 34
Pastoriza, M. G.; Storchi-Bergmann, T.; Ricci, T. V. +8 more
The merger remnant NGC 34 is a local luminous infrared galaxy (LIRG) hosting a nuclear starburst and a hard X-ray source associated with a putative, obscured Seyfert 2 nucleus. In this work, we use adaptive optics assisted near-infrared (NIR) integral field unit observations of this galaxy to map the distribution and kinematics of the ionized and …