Search Publications
X-ray variability of cool stars: Magnetic activity and accretion
Stelzer, B.
This article provides a review of X-ray variability from late-type stars with particular focus on the achievements of XMM-Newton and its potential for future studies in this field.
Statistical imprints of CMB B-type polarization leakage in an incomplete sky survey analysis
Wang, Kai; Santos, Larissa; Zhao, Wen +2 more
One of the main goals of modern cosmology is to search for primordial gravitational waves by looking on their imprints in the B-type polarization in the cosmic microwave background radiation. However, this signal is contaminated by various sources, including cosmic weak lensing, foreground radiations, instrumental noises, as well as the E-to-B lea…
New Horizons Upper Limits on O2 in Pluto’s Present Day Atmosphere
Stern, S. A.; Olkin, C. B.; Weaver, H. A. +7 more
The surprising discovery by the Rosetta spacecraft of molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko challenged our understanding of the inventory of this volatile species on and inside bodies from the Kuiper Belt. That discovery motivated our search for oxygen in the atmosphere of Kuiper Belt planet Pluto, because…
High-resolution spectroscopy and abundance analysis of δ Scuti stars near the γ Doradus instability strip
Kambe, E.; Niemczura, E.; Molenda-Żakowicz, J. +5 more
δ Scuti stars are remarkable objects for asteroseismology. In spite of decades of investigations, there are still important questions about these pulsating stars to be answered, such as their positions in log Teff-log g diagram, or the dependence of the pulsation modes on atmospheric parameters and rotation. Therefore, we performed a de…
JVLA Observations of IC 342: Probing Star Formation in the Nucleus
Goss, W. M.; Johnson, K. E.; Kepley, Amanda A. +2 more
IC 342 is a nearby, late-type spiral galaxy with a young nuclear star cluster surrounded by several giant molecular clouds. The IC 342 nuclear region is similar to the Milky Way and therefore provides an interesting comparison. We explore star formation in the nucleus using radio recombination line (RRL) and continuum emission at 5, 6.7, 33, and 3…
New eruptive variable in the massive star-forming region associated with IRAS 18507+0121
Nikoghosyan, E. H.; Azatyan, N. M.; Khachatryan, K. G.
Aims: We report the discovery of a strong outburst of the embedded young stellar object (YSO) UKIDSS-J185318.36+012454.5, located in the star-forming region associated with IRAS 18507+0121 and the ultra-compact H II region GAL 034.4+00.23.
Methods: Using archival photometric data and images, we determined the amplitude and the epoch of t…
Joint fit of Warm Absorbers in COS and HETG spectra of NGC 3783
Sun, Wei; Ji, Li; Fu, Xiao-Dan +2 more
Warm Absorbers (WAs), as an important form of AGN outflows, show absorption in both the UV and X-ray bands. Using XSTAR generated photoionization models, for the first time we present a joint fit to the simultaneous observations of HST/COS and Chandra/HETG on NGC 3783. A total of five WAs explain well all absorption features from the AGN outflows,…
Sharp spectral features from light dark matter decay via gravity portals
Ibarra, Alejandro; Catà, Oscar; Ingenhütt, Sebastian
We investigate the phenomenology of dark matter decay assuming that it is induced by non-minimal coupling to gravity, when the dark matter mass is in the sub-GeV range, i.e. below the QCD confinement scale. We show that the decay of the singlet scalar dark matter candidate produces sharp features in the photon spectrum, in the form of lines, boxes…
A SOFIA FORCAST Grism Study of the Mineralogy of Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables
Gehrz, R. D.; Lebzelter, T.; Hinkle, K. H. +10 more
We present a SOFIA FORCAST grism spectroscopic survey to examine the mineralogy of the circumstellar dust in a sample of post-asymptotic giant branch (post-AGB) yellow supergiants that are believed to be the precursors of planetary nebulae. Our mineralogical model of each star indicates the presence of both carbon-rich and oxygen-rich dust species…
Investigating the nature of the INTEGRAL gamma-ray bursts and sub-threshold triggers with Swift follow-up
Götz, D.; Mereghetti, S.; Gehrels, N. +9 more
We explore the potential of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) to improve our understanding of the low-fluence regime for explosive transients, such as Gamma-ray Bursts (GRBs). We probe the nature of the so-called 'WEAK' INTEGRAL triggers, when the gamma-ray instruments record intensity spikes that are below the usual S…