Search Publications
The family pictures of our neighbours: investigating the mass function and dynamical parameters of nearby open clusters
Sollima, A.; Haghi, H.; Ebrahimi, H.
We determine the mass functions (MFs) and the dynamical parameters of 15 nearby open clusters (OCs), using the unprecedented data set of the Gaia Early Data Release 3. We select the members of each cluster by combining the photometric (colour and magnitude) and astrometric (parallax and proper motions) parameters of stars, minimizing the contamina…
Project Hephaistos - I. Upper limits on partial Dyson spheres in the Milky Way
Wright, Jason T.; Zackrisson, Erik; Korn, Andreas J. +2 more
Dyson spheres are hypothetical megastructures built by advanced extraterrestrial civilizations to harvest radiation energy from stars. Here, we combine optical data from Gaia DR2 with mid-infrared data from AllWISE to set the strongest upper limits to date on the prevalence of partial Dyson spheres within the Milky Way, based on their expected was…
The stellar 'Snake' - I. Whole structure and properties
Fang, Min; Wang, Fan; Tian, Haijun +10 more
To complement our previous discovery of the young snake-like structure in the solar neighbourhood and reveal the structure's full extent, we build two samples of stars within the Snake and its surrounding territory from Gaia Early Data Release 3 (EDR3). With the friends-of-friends algorithm, we identify 2694 and 9052 Snake member candidates from t…
The structure and 3D kinematics of vela OB2
Wright, Nicholas J.; Cantat-Gaudin, Tristan; Jeffries, R. D. +2 more
The kinematics of stars in OB associations can provide insights into their formation, dynamical evolution, and eventual fate. The low-mass stellar content of OB associations are sufficiently numerous as to provide a detailed sampling of their kinematic properties, however spectroscopy is required to confirm the youth of individual stars and to get…
Bending waves excited by irregular gas inflow along warps
Debattista, Victor P.; Beraldo e Silva, Leandro; Khachaturyants, Tigran +1 more
Gaia has revealed clear evidence of bending waves in the vertical kinematics of stars in the solar neighbourhood. We study bending waves in two simulations, one warped, with the warp due to misaligned gas inflow, and the other unwarped. We find slow, retrograde bending waves in both models, with the ones in the warped model having larger amplitude…
Nebular-phase spectra of Type Ia supernovae from the Las Cumbres Observatory Global Supernova Project
Wheeler, J. C.; Galbany, L.; Howell, D. A. +17 more
The observed diversity in Type Ia supernovae (SNe Ia) - the thermonuclear explosions of carbon-oxygen white dwarf stars used as cosmological standard candles - is currently met with a variety of explosion models and progenitor scenarios. To help improve our understanding of whether and how often different models contribute to the occurrence of SNe…
Characterization of hot populations of Melotte 66 open cluster using Swift/UVOT
Subramaniam, Annapurni; Panthi, Anju; Vaidya, Kaushar +3 more
Ultraviolet (UV) wavelength observations have made a significant contribution to our understanding of hot stellar populations of star clusters. Multiwavelength spectral energy distributions (SEDs) of stars, including ultraviolet observations, have proven to be an excellent tool for discovering unresolved hot companions in exotic stars such as blue…
Phase spirals in cosmological simulations of Milky Way-sized galaxies
Antoja, T.; Ramos, P.; García-Conde, B. +2 more
We study the vertical perturbations in the galactic disc of the Milky Way-size high-resolution hydrodynamical cosmological simulation named GARROTXA. We detect phase spirals in the vertical projection Z - VZ of disc's stellar particles for the first time in this type of simulations. Qualitatively similar structures were detected in the …
Ensemble-based unsupervised machine learning method for membership determination of open clusters using Mahalanobis distance
Deb, Sukanta; Baruah, Amiya; Kumar, Subhash
We present an improved method for the determination of membership of an open cluster using ensemble-based unsupervised machine learning techniques. The working principle of this method relies on two stages: (i) choosing a suitable range of three astrometric parameters (π, µαcos δ, µδ) using k-nearest neighbour (kN…
TYC 2990-127-1: An Algol-type SB2 binary system of subgiant and red giant with a probable ongoing mass-transfer
Han, Zhanwen; Kovalev, Mikhail; Chen, Xuefei +3 more
We present a study of the spectroscopic binary TYC 2990-127-1 from the LAMOST survey. We use full-spectrum fitting to derive radial velocities and spectral parameters. The high mass ratio indicates that the system underwent mass transfer in the past. We compute the orbital solution and find that it is a very close sub-giant/red giant pair on circu…