Search Publications
The exceptional X-ray evolution of SN 1996cr in high resolution
Bauer, F. E.; Brandt, W. N.; Quirola-Vásquez, J. +4 more
We present X-ray spectra spanning 18 yr of evolution for SN 1996cr, one of the five nearest SNe detected in the modern era. Chandra HETG exposures in 2000, 2004, and 2009 allow us to resolve spectrally the velocity profiles of Ne, Mg, Si, S, and Fe emission lines and monitor their evolution as tracers of the ejecta-circumstellar medium interaction…
Towards observing reverberating and superefficient pulsar wind nebulae
Coti Zelati, Francesco; Torres, Diego F.; Lin, Tingting
In a recent work, we numerically studied the radiative properties of the reverberation phase of pulsar wind nebulae (PWNe), i.e. when the reverse shock created by the supernova explosion travels back towards the pulsar, compressing the wind bubble. We focused on several well-characterized PWNe and used them as examples for introducing the concept …
Gamma-Ray Polarimetry: A New Window for the Nonthermal Universe
Ilie, Cosmin
Over the past few decades, impressive progress has been made in the field of photon polarimetry, especially in the hard X-ray and soft gamma-ray energy regime. Measurements of the linear degree of polarization for some of the most energetic astrophysical sources, such as gamma-ray bursts (GRBs) or blazars, are now possible, at energies below the p…
Search for water outgassing of (1) Ceres near perihelion
Russell, C. T.; Mousis, O.; Vernazza, P. +13 more
Context. (1) Ceres is the largest body in the main asteroid belt and one of the most intriguing objects in the solar system, in part because of the discovery of water outgassing by the Herschel Space Observatory (HSO) and its still-debated origin. Ceres was the target of NASA's Dawn spacecraft for 3.5 yr, which achieved a detailed characterization…
Nonequilibrium Ionization Effects on Coronal Plasma Diagnostics and Elemental Abundance Measurements
Landi, Enrico; Shi, Tong; Manchester, Ward, IV
Plasma diagnostics and elemental abundance measurements are crucial to help us understand the formation and dynamics of the solar wind. Here we use a theoretical solar wind model to study the effect of nonequilibrium ionization (NEI) on plasma diagnostic techniques applied to line intensities emitted by the fast solar wind. We find that NEI almost…
A Sparkler in the Fireworks Galaxy: Discovery of an Ultraluminous X-Ray Transient with a Strong Oxygen Line in NGC 6946
Soria, Roberto; Wang, Junfeng; Wang, Chen
We discovered and studied an ultraluminous X-ray source (CXOU J203451.1+601043) that appeared in the spiral galaxy NGC 6946 at some point between 2008 February and 2012 May and has remained at luminosities ≈2-4 × 1039 erg s-1 in all observations since then. Our spectral modeling shows that the source is generally soft but wit…
Multiwavelength Modeling of the SED of Nova V339 Del: Stopping the Wind and Long-lasting Super-Eddington Luminosity with Dust Emission
Skopal, Augustin
During the classical nova outburst, the radiation generated by the nuclear burning of hydrogen in the surface layer of a white dwarf (WD) is reprocessed by the outer material into different forms at softer energies, whose distribution in the spectrum depends on the nova age. Using the method of multiwavelength modeling the spectral energy distribu…
Retrieval of Chemical Abundances in Titan's Upper Atmosphere From Cassini UVIS Observations With Pointing Motion
Gao, Peter; Fan, Siteng; Li, Cheng +3 more
Cassini/Ultraviolet Imaging Spectrograph (UVIS) Far-UV observations of stellar occultations at Titan are well suited for probing its atmospheric composition and structure. However, due to instrument pointing motion, only 5 out of tens of observations have been analyzed. We present an innovative retrieval method that corrects for the effect of poin…
ATLASGAL-selected massive clumps in the inner Galaxy. VII. Characterisation of mid-J CO emission
König, C.; Menten, K. M.; Csengeri, T. +7 more
Context. High-mass stars are formed within massive molecular clumps, where a large number of stars form close together. The evolution of the clumps with different masses and luminosities is mainly regulated by their high-mass stellar content and the formation of such objects is still not well understood.
Aims: In this work, we characterise th…
Parameters of the Link between the Optical and Radio Frames from Gaia DR2 Data and VLBI Measurements
Bobylev, V. V.
Based on published data, we have assembled a sample of 88 radio stars for which there are both trigonometric parallax and proper motion measurements in the Gaia DR2 catalogue and VLBI measurements. A new estimate of the systematic offset between the optical and radio frames has been obtained by analyzing the Gaia-VLBI trigonometric parallax differ…