Search Publications
Modeling Balmer line signatures of stellar CMEs
Heinzel, P.; Odert, P.; Leitzinger, M.
From the Sun, we know that coronal mass ejections (CMEs) are a transient phenomenon, often correlated with flares. They have an impact on solar mass- and angular momentum loss, and therefore solar evolution, and make a significant part of space weather. The same is true for stars, but stellar CMEs are still not well constrained, although new metho…
The whisper of a whimper of a bang: 2400 d of the Type Ia SN 2011fe reveals the decay of 55Fe
Kochanek, C. S.; Stanek, K. Z.; Ashall, C. +4 more
We analyse new multifilter Hubble Space Telescope (HST) photometry of the normal Type Ia supernova (SN Ia) 2011fe out to ≈2400 d after maximum light, the latest observations to date of a SN Ia. We model the pseudo-bolometric light curve with a simple radioactive decay model and find energy input from both 57Co and 55Fe are ne…
Spectropolarimetry of magnetic Chemically Peculiar stars in the Orion OB1 association
Semenko, Eugene; Romanyuk, Iosif; Yakunin, Ilya +2 more
We summarize the results of a spectropolarimetric survey of 56 chemically peculiar (CP) stars in the association of Orion OB1. We uniformly collected the observational material with the 6-m telescope BTA of the Special Astrophysical Observatory in 2013-2021. We identify 14 new magnetic CP stars with a longitudinal magnetic field exceeding approxim…
Inferring the morphology of AGN torus using X-ray spectra: a reliability study
Markowitz, Alex G.; Buchner, Johannes; Saha, Tathagata
Numerous X-ray spectral models have been developed to model emission reprocessed by the torus of an active galactic nucleus (AGN), e.g. UXCLUMPY, CTORUS, and MYTORUS. They span a range of assumed torus geometries and morphologies - some posit smooth gas distributions, and others posit distributions of clouds. It is suspected that given the quality…
High-precision star-formation efficiency measurements in nearby clouds
Gutermuth, Robert A.; Pokhrel, Riwaj; Hu, Zipeng +1 more
On average molecular clouds convert only a small fraction ϵff of their mass into stars per free-fall time, but different star-formation theories make contrasting claims for how this low mean efficiency is achieved. To test these theories, we need precise measurements of both the mean value and the scatter of ϵff, but high-pre…
LeMMINGs - IV. The X-ray properties of a statistically complete sample of the nuclei in active and inactive galaxies from the Palomar sample
Muxlow, T. W. B.; Argo, M. K.; Knapen, J. H. +22 more
All 280 of the statistically complete Palomar sample of nearby (<120 Mpc) galaxies δ > 20° have been observed at 1.5 GHz as part of the LeMMINGs e-MERLIN legacy survey. Here, we present Chandra X-ray observations of the nuclei of 213 of these galaxies, including a statistically complete sub-set of 113 galaxies in the declination range 40° &l…
CoBiToM Project - II. Evolution of contact binary systems close to the orbital period cut-off
Hatzidimitriou, D.; Hakala, P.; Liakos, A. +7 more
Ultra-short orbital period contact binaries (Porb < 0.26 d) host some of the smallest and least massive stars. These systems are faint and rare, and it is believed that they have reached a contact configuration after several Gyrs of evolution via angular momentum loss, mass transfer, and mass loss through stellar wind processes. This…
UOCS -VIII. UV study of the open cluster NGC 2506 using ASTROSAT★
Subramaniam, Annapurni; Panthi, Anju; Vaidya, Kaushar +4 more
We study an intermediate-age open cluster (OC) NGC 2506 using the ASTROSAT/UVIT data and other archival data. We identified 2175 cluster members using a machine learning-based algorithm, ML-MOC, on Gaia EDR3 data. Among the cluster members detected in UVIT filters, F148W, F154W, and F169M, we detect nine blue straggler stars (BSS), three yellow st…
Hard-X-ray-selected active galactic nuclei - II. Spectral energy distributions in the 5-45 GHz domain
Laor, Ari; Behar, Ehud; Baldi, Ranieri D. +7 more
A wide-frequency radio study of active galactic nuclei (AGN) is crucial to evaluate the intervening radiative mechanisms responsible for the observed emission and relate them with the underlying accretion physics. We present wide-frequency (5-45 GHz), high-sensitivity (few $\mathrm{{\mu }Jy\, beam^{-1}}$), (sub)-kpc Jansky Very Large Array (JVLA) …
The white dwarf binary pathways survey - VII. Evidence for a bi-modal distribution of post-mass transfer systems?
Gänsicke, B. T.; Parsons, S. G.; Hernandez, M. S. +5 more
Binary systems consisting of a white dwarf (WD) and a main-sequence companion with orbital periods up to ≈100 d are often thought to be formed through common envelope evolution which is still poorly understood. To provide new observational constraints on the physical processes involved in the formation of these objects, we are conducting a large-s…