Search Publications
Missions
Journals
Publication Years
The Composition, Excitation, and Physical State of Atomic Gas in the Debris Disk Surrounding 51 Oph
Jenkins, Edward B.; Gry, Cécile
We measured 304 absorption features in the ultraviolet and visible spectra of the star 51 Oph, which is known to have a debris disk with a high inclination. We analyzed the relative populations of atoms in excited fine-structure and metastable levels that are maintained by optical pumping and collisional excitation by electrons, and we found that …
The fractal nature as new frontier in microstructural characterization and relativization of scale sizes within space
Arnold, Walter; Mitic, Vojislav V.; Lazovic, Goran +3 more
Today in the age of advanced ceramic civilization, there are a variety of applications for modern ceramics materials with specific properties. Our up-to date research recognizes that ceramics have a fractal configuration nature on the basis of different phenomena. The key property of fractals is their scale-independence. The practical value is tha…
The fate of O+ ions observed in the plasma mantle: particle tracing modelling and cluster observations
Nilsson, Hans; Gunell, Herbert; Slapak, Rikard +5 more
Ion escape is of particular interest for studying the evolution of the atmosphere on geological timescales. Previously, using Cluster-CODIF data, we investigated the oxygen ion outflow from the plasma mantle for different solar wind conditions and geomagnetic activity. We found significant correlations between solar wind parameters, geomagnetic ac…
Two New Rapidly Rotating ON Stars Found with LAMOST
Howarth, Ian D.; Li, Guang-Wei
The ON stars are a rare subtype of O stars of uncertain origin. We report two new, rapidly rotating ON stars found in data acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. LS I +61 28 is an ON8.5 Vn dwarf with a projected equatorial rotational velocity of {V}{{e}}\sin I≃ 298 {km} {{{s}}}-1, while H…
An empirical metallicity tracer in CEMP and C-normal stars
Hansen, C. J.; Reichert, M.; Singh, D. +2 more
Context. Deriving the metallicity, [Fe/H], in low-resolution spectra of carbon-enhanced metal-poor (CEMP) stars is a tedious task that, owing to the large number of line blends, often leads to uncertainties on [Fe/H] exceeding 0.25 dex. The CEMP stars increase in number with decreasing [Fe/H] and some of these are known to be bona fide second gene…
Census of the Young Stellar Population in the Galactic H II Region Sh2-242
Joshi, Santosh; Dutta, Somnath; Mondal, Soumen +3 more
We present here identification and characterization of the young stellar population associated with an active star-forming site Sh2-242. We used our own new optical imaging and spectroscopic observational data, as well as several archival catalogs, e.g., Pan-STARRS 1, Gaia DR2, IPHAS, Wide-field InfraRed Camera, 2MASS, and Spitzer. Slit spectrosco…
ALMA and NACO observations towards the young exoring transit system J1407 (V1400 Cen)
Hales, A.; van der Marel, N.; Min, M. +8 more
Aims: Our aim was to directly detect the thermal emission of the putative exoring system responsible for the complex deep transits observed in the light curve for the young Sco-Cen star 1SWASP J140747.93-394542.6 (V1400 Cen, hereafter J1407), confirming it as the occulter seen in May 2007, and to determine its orbital parameters with respect …
Pulsation and rotation in NGC 6811: the Kepler short-cadence stars
Rodríguez, E.; Martín-Ruiz, S.; Rodríguez-López, C. +3 more
We have analysed a selected sample of 36 Kepler short-cadence stars in the field of NGC 6811. The results reveal that all the targets are variable: two red giant stars with solar-like oscillations, 21 main-sequence pulsators (16 δ Scuti and five γ Doradus stars), and 13 rotating variables. Three new γ Doradus (γ Dor) variables (one is a hot γ Dor …
Light curve analysis of ground-based data from exoplanets transit database
Poro, A.; Davoudi, F.; Khakpash, S. +9 more
Photometric observations of exoplanet transits can be used to derive the orbital and physical parameters of an exoplanet. We analyzed several transit light curves of exoplanets that are suitable for ground-based observations whose complete information is available on the Exoplanet Transit Database (ETD). We analyzed transit data of planets includi…
Miscellaneous photometric variations in cataclysmic variables: V455 And, SS Cyg, AQ Men, LQ Peg, RW Tri and UX UMa
Bruch, Albert
Cataclysmic variables are among the photometrically most unstable star in the zoo of stellar objects, exhibiting light variations on all time-scales between millennia and seconds. The literature is full of reports on variable phenomena which often require independent confirmation before they can be accepted as established facts. In this contributi…