Search Publications
Discovery of a long-lived, high-amplitude dusty infrared transient
Maccarone, T. J.; Torres, M. A. P.; Nelemans, G. +15 more
We report the detection of an infrared-selected transient which has lasted at least five years, first identified by a large mid-infrared and optical outburst from a faint X-ray source detected with the Chandra X-ray Observatory. In this paper we rule out several scenarios for the cause of this outburst, including a classical nova, a luminous red n…
The 26 December 2001 Solar Event Responsible for GLE63. I. Observations of a Major Long-Duration Flare with the Siberian Solar Radio Telescope
Grechnev, V. V.; Kochanov, A. A.
Ground level enhancements (GLEs) of cosmic-ray intensity occur, on average, once a year. Because they are rare, studying the solar sources of GLEs is especially important to approach understanding their origin. The SOL2001-12-26 eruptive-flare event responsible for GLE63 seems to be challenging in some aspects. Deficient observations limited our u…
An intermediate-mass black hole candidate in M51?
Earnshaw, H. M.
We present the current results of an investigation into M51 ULX-7, using archival data from XMM-Newton, Chandra and NuSTAR, and optical and radio data from HST and VLA. The source has a consistently hard power-law X-ray spectrum and high short-term variability. This is unusual variability behaviour for a ULX, as we would expect highly variable ULX…
Near-Infrared Polarization Source Catalog of the Northeastern Regions of the Large Magellanic Cloud
Tamura, Motohide; Jeong, Woong-Seob; Pak, Soojong +2 more
We present a near-infrared band-merged photometric and polarimetric catalog for the 39‧ × 69‧ fields in the northeastern part of the Large Magellanic Cloud (LMC), which were observed using SIRPOL, an imaging polarimeter of the InfraRed Survey Facility. This catalog lists 1858 sources brighter than 14 mag in the H band with a polarization signal-to…
Polar cap magnetic field reversals during solar grand minima: could pores play a role?
Švanda, Michal; Brun, Allan Sacha; Roudier, Thierry +1 more
We study the magnetic flux carried by pores located outside active regions with sunspots and investigate their possible contribution to the reversal of the global magnetic field of the Sun. We find that they contain a total flux of comparable amplitude to the total magnetic flux contained in polar caps. The pores located at distances of 40-100 Mm …
The peculiar megamaser AGN NGC 1194: Comparison with the warped disk candidates NGC 1068 and NGC 4258
Vasylenko, A.; Fedorova , E.; Hnatyk, B. I. +1 more
We analyze the X-ray properties of the Compton-thick Seyfert 1.9 radio quiet AGN in NGC 1194 using INTEGRAL (ISGRI), XMM-Newton (EPIC), Swift (BAT and XRT), and Suzaku (XIS) observations. There is a set of Fe-K lines in the NGC 1194 spectrum with complex relativistic profiles that can be considered as a sign of either a warped Bardeen-Petterson ac…
On More Sensitive Periodogram Statistics
Bélanger, G.
Period searches in event data have traditionally used the Rayleigh statistic, R 2. For X-ray pulsars, the standard has been the Z 2 statistic, which sums over more than one harmonic. For γ-rays, the H-test, which optimizes the number of harmonics to sum, is often used. These periodograms all suffer from the same problem, name…
Effects of disc asymmetries on astrometric measurements. Can they mimic planets?
Schneider, J.; Souami, D.; Kral, Q. +1 more
Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement…
Prediction of Forbidden Ultraviolet and Visible Emissions in Comet 67P/Churyumov-Gerasimenko
Galand, Marina; Bhardwaj, Anil; Raghuram, Susarla
Remote observation of spectroscopic emissions is a potential tool for the identification and quantification of various species in comets. The CO Cameron band (to trace CO2) and atomic oxygen emissions (to trace H2O and/or CO2, CO) have been used to probe neutral composition in the cometary coma. Using a coupled-che…
Deriving Potential Coronal Magnetic Fields from Vector Magnetograms
Welsch, Brian T.; Fisher, George H.
The minimum-energy configuration for the magnetic field above the solar photosphere is curl-free (hence, by Ampère's law, also current-free), so can be represented as the gradient of a scalar potential. Since magnetic fields are divergence free, this scalar potential obeys Laplace's equation, given an appropriate boundary condition (BC). With meas…