Search Publications
Is there a black hole in the center of the Sun?
Bellinger, Earl P.; Caplan, Matthew E.; Santarelli, Andrew D.
There is probably not a black hole in the center of the Sun. Despite this detail, our goal in this work to convince the reader that this question is interesting and that work studying stars with central black holes is well motivated. If primordial black holes exist then they may exist in sufficiently large numbers to explain the dark matter in the…
On the mass assembly history of the Milky Way: clues from its stellar halo
Horta, Danny; Schiavon, Ricardo P.
Stellar halos of galaxies retain crucial clues to their mass assembly history. It is in these galactic components that the remains of cannibalised galactic building blocks are deposited. For the case of the Milky Way, the opportunity to analyse the stellar halo's structure on a star-by-star basis in a multi-faceted approach provides a basis from w…
Galaxy formation catalyzed by gravastars and the JWST, revisited
Adler, Stephen L.
We have proposed that galaxy formation is catalyzed by the collision of infalling and outstreaming particles from leaky, horizonless astrophysical black holes, most likely gravastars, and based on this gave a model for the disk galaxy scale length. In this paper we modify our original scale length formula by including an activation probability
Classification and characterization using HCT/HFOSC spectra of carbon stars selected from the HES survey
Goswami, Aruna; Purandardas, Meenakshi
We present results from the analysis of 88 carbon stars selected from Hamburg/ESO (HES) survey using low-resolution spectra (R ∼1330 & 2190). The spectra were obtained with the Himalayan Faint Object Spectrograph Camera (HFOSC) attached to the 2-m Himalayan Chandra Telescope (HCT). Using well-defined spectral criteria based on the strength of …
Following the tidal trail: a history of modeling the Magellanic Stream
Lucchini, Scott
The formation of the Magellanic Stream has puzzled astronomers for decades. In this review, we outline the history of our understanding of the Magellanic System highlighting key observations that have revolutionized thinking of its evolution. We also walk through the major models and theoretical advances that have led to our current paradigm ‑ (1)…
Self-absorption in solar surge as observed by IRIS
Kayshap, Pradeep; Babu, B. Suresh; Tripathi, Sharad C.
Solar surges are collimated flows of plasma that occur in the periphery of active regions (ARs). The kinematics, physical properties, and triggering mechanisms of a solar surge were studied through imaging and spectroscopic diagnosis. The surge has a typical inverted Y-shape, and it moves with a speed of more than 200 km/s in the transition-region…
A review of 70 years with astrometry: From meridian circles to Gaia and beyond
Høg, Erik
In 1953 I heard of an experiment in 1925 by Bengt Strömgren where he observed transit times with the meridian circle at the Copenhagen University Observatory measuring the current in a photocell behind slits when a star was crossing. In 1954 just 22 years old I was given the task as a student to make first test observations with a new meridian cir…
Search and study of young infrared stellar clusters
Azatyan, Naira
The main aim of this paper is to study both the Interstellar Medium (ISM) and the young stellar population in the three star-forming regions, namely IRAS 05137+3919, 05168+3634, and 19110+1045. The study of the ISM includes determination of the hydrogen column density (N(H2)) and dust temperature (Td) in the regions using mod…
Investigative study of five low mass ratio semi-detached binaries
Stassun, Keivan G.; Parthasarathy, Mudumba; Jagirdar, Rukmini +2 more
We present the first pulsation analysis of four totally eclipsing Algol systems S Cnc, SS Cet, TW And, and VW Cyg using the latest data available from Kepler (K2), and TESS databases. Based on the characteristics observed they are classified to be oscillating eclipsing Algol binaries with primary components having
Deep learning-based prediction of CME-driven shock standoff distances in metric type II radio emissions
Elsaid, Ahmed; Mahrous, Ayman; Hamada, Amr +1 more
Type II radio emissions are events mostly found to be associated with coronal mass ejections (CMEs) and accelerated by the CME-driven shock in the heliosphere. This study reports on the estimation of the CME-shock standoff distance at the commencement of metric type II radio emissions by combining the CME-deprojected speed and spectral features of…