Search Publications
NGC 7314: X-Ray Study of the Evolving Accretion Properties
Chang, Hsiang-Kuang; Chatterjee, Debjit; Jana, Arghajit +1 more
We present a comprehensive analysis of the timing and spectral properties of NGC 7314, a Seyfert 1.9 galaxy, using X-ray observations from XMM-Newton, NuSTAR, and RXTE/proportional counter array (PCA). The timing analysis reveals significant variability across different energy bands, with fractional variability values consistent with previous stud…
Luminosity Class of the Symbiotic Stars 4U1954+319 and ZZ CMi
Zamanov, R.; Stoyanov, K. A.; Takey, A. +9 more
We performed optical photometry and spectral observations of the symbiotic stars 4U1954+319 and ZZ CMi. For 4U1954+319, using high-resolution spectra, we, measure the equivalent widths of diffuse interstellar bands (DIBs) and estimate the interstellar reddening E(B−V)=0.83 ± 0.09. Using the GAIA distances and our photometry, we find: (1) the absol…
HD 214220 (BD+56 2813): An eclipsing binary with its primary component at the end of the main sequence
Schmutz, W.
Context. Analysis of the light curves of an eclipsing binary allows one to derive the absolute dimensions of the system. This in turn yields information on the radii of the components, which allows the stars to be accurately placed on the Hertzsprung-Russell diagram and their evolutionary phase to be interpreted via comparisons to tracks of stella…
The Stellar Content of the Young Open Cluster Berkeley 50 (IC 1310)
Massey, Philip; Speckert, Meghan; Skiff, Brian A.
We observed the Galactic open cluster Berkeley 50 in order to determine its stellar content, distance, and age. We obtained UBV photometry of 1145 stars in a 12.'3 × 12.'3 field, and used Gaia proper motions and parallaxes to identify 64 members, of which we obtained spectra of the 17 brightest members. The majority of the observed population we c…
Hard X-rays from the deep solar atmosphere. An unusual UV burst with flare properties
Peter, H.; Chitta, L. P.; Young, P. R. +4 more
Explosive transient events occur throughout the solar atmosphere. The differing manifestations range from coronal mass ejections to Ellermann bombs. The former may have negligible signatures in the lower atmosphere, and the latter may have negligible nonthermal emissions such as hard X-radiation. A solar flare generally involves a broad range of e…
The 24 Aqr triple system: A closer look at its unique high-eccentricity hierarchical architecture
Horch, Elliott P.; Abushattal, Ahmad A.; Al-Wardat, Mashhoor A. +4 more
As its periastron passage occurred during the third quarter of 2020, system 24 Aqr is of particular significance. New visual solutions for the latest speckle interferometry observations collected by the Lowell Discovery Telescope (LTD) with its new QWSSI speckle camera are presented here. A variety of techniques were used to analyze the system, in…
Filling in the blanks: A method to infer the substructure membership and dynamics of 5D stars
Helmi, Amina; Callingham, Thomas M.
Context. In the solar neighbourhood, only ∼2% of stars in the Gaia survey have a line-of-sight velocity (vlos) contained within the RVS catalogue. These limitations restrict conventional dynamical analysis, such as finding and studying substructures in the stellar halo. Aims. We aim to present and test a method to infer a probability de…
The miniJPAS survey. Multiwavelength exploration of detected Extreme Emission Line Galaxies
Mendes de Oliveira, Claudia; Benítez, Narciso; Amarantidis, Stergios +24 more
Extreme Emission Line Galaxies (EELGs) stand as remarkable objects due to their extremely metal poor environment and intense star formation. Considered as local analogues of high-redshift galaxies in the peak of their star-forming activity, they offer insights into conditions prevalent during the early Universe. Assessment of their stellar and gas…
AstroSat observations of the dipping low-mass X-ray binary XB 1254-690
Rao, A. R.; Misra, Ranjeev; Navale, Nilam R. +4 more
XB 1254-690 is a neutron star low-mass X-ray binary with an orbital period of 3.88 h, and it exhibits energy-dependent intensity dips, thermonuclear bursts, and flares. We present the results of an analysis of a long observation of this source using the AstroSat satellite. The X-ray light curve gradually changed from a high-intensity flaring state…
Multiline study of the radial extent of SiO, CS, and SiS in asymptotic giant branch envelopes
Cernicharo, J.; Fonfría, J. P.; Agúndez, M. +3 more
Circumstellar envelopes around asymptotic giant branch (AGB) stars contain a rich diversity of molecules, whose spatial distribution is regulated by different chemical and physical processes. In the outer circumstellar layers, all molecules are efficiently destroyed due to interactions with interstellar ultraviolet photons. Here we aim to carry ou…