Search Publications
Ground-based observation of ZZ Ceti stars and the discovery of four new variables
Kepler, S. O.; Romero, Alejandra D.; Koester, D. +7 more
We perform ground-based photometric observations of 22 DA white dwarf stars, 10 already known ZZ Cetis and 12 candidates with atmospheric parameters inside the classical instability strip. We report on the discovery of four new variable DA white dwarf stars. Two objects are near the middle of the instability strip, SDSS J082804.63+094956.6 and SDS…
Origin of hydrogen fluoride emission in the Orion Bar. An excellent tracer for CO-dark H2 gas clouds
Shipman, R. F.; van der Tak, F. F. S.; Tielens, A. G. G. M. +1 more
Context. The hydrogen fluoride (HF) molecule is seen in absorption in the interstellar medium (ISM) along many lines of sight. Surprisingly, it is observed in emission toward the Orion Bar, which is an interface between the ionized region around the Orion Trapezium stars and the Orion molecular cloud.
Aims: We aim to understand the origin of …
Collisions of acoustic solitons and their electric fields in plasmas at critical compositions
Verheest, Frank; Hereman, Willy A.
Acoustic solitons obtained through a reductive perturbation scheme are normally governed by a Korteweg-de Vries (KdV) equation. In multispecies plasmas at critical compositions the coefficient of the quadratic nonlinearity vanishes. Extending the analytic treatment then leads to a modified KdV (mKdV) equation, which is characterized by a cubic non…
Observationally inferred dark matter phase-space distribution and direct detection experiments
Mandal, Sayan; Majumdar, Subhabrata; Rentala, Vikram +1 more
We present a detailed analysis of the effect of an observationally determined dark matter (DM) velocity distribution function (VDF) of the Milky Way (MW) on DM direct detection rates. We go beyond local kinematic tracers and use rotation curve data up to 200 kpc to construct a MW mass model and self-consistently determine the local phase-space dis…
Identification of AGN in the XMM-Newton X-ray survey of the SMC
Maitra, Chandreyee; Haberl, Frank; Cioni, Maria-Rosa L. +2 more
Context. Finding active galactic nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recently that the number of AGN known behind the SMC has increased by several orders of magnitude. <…
A hyper-runaway white dwarf in Gaia DR2 as a Type Iax supernova primary remnant candidate
Ruffini, Nicholas J.; Casey, Andrew R.
Observations of stellar remnants linked to Type Ia and Type Iax supernovae are necessary to fully understand their progenitors. Multiple progenitor scenarios predict a population of kicked donor remnants and partially burnt primary remnants, both moving with relatively high velocity. But only a handful of examples consistent with these two predict…
DW Cancri in X-rays
Conversi, L.; Nucita, A. A.; Licchelli, D.
We report on the XMM-Newton observation of DW Cnc, a candidate intermediate polar candidate whose historical optical light curve shows the existence of periods at ≃38, ≃86, and ≃69 min, which were interpreted as the white dwarf spin, the orbital and the spin-orbit beat periodicities. By studying the 0.3-10 keV light curves, we confirm the existenc…
The Giant Herbig-Haro Flow HH 212 and Associated Star Formation
Bally, John; Raga, A. C.; Geballe, T. R. +5 more
The bipolar jet HH 212 is one of the finest collimated jets known. It has up to now been detected only in near-infrared H2 emission, but here we present deep optical images that show that two of the major bow shocks are weakly detected in optical [S II] emission, as expected for a bona fide Herbig-Haro jet. We also present widefield H
ISPY - NaCo Imaging Survey for Planets around Young stars. Discovery of an M dwarf in the gap between HD 193571 and its debris ring
Reffert, Sabine; Metchev, Stanimir; Rickman, Emily L. +19 more
Context. The interaction between low-mass companions and the debris discs they reside in is still not fully understood. A debris disc can evolve due to self-stirring, a process in which planetesimals can excite their neighbours to the point of destructive collisions. In addition, the presence of a companion could further stir the disc (companion-s…
Dwarf Galaxy Discoveries from the KMTNet Supernova Program. II. The NGC 3585 Group and Its Dynamical State
Cha, Sang-Mok; Lee, Yongseok; Moon, Dae-Sik +4 more
We present our discovery and analysis of dwarf galaxies in the NGC 3585 galaxy group by the Korea Microlensing Telescope Network (KMTNet) Supernova Program. Using deep stack images reaching ≃28 mag arcsec-2 in BVI, we discovered 46 dwarf galaxy candidates distributed in a field of 7 square degrees. The dwarf galaxy candidates exhibit a …