Search Publications
Observational clues to the magnetic evolution of magnetars
Enoto, Teruaki; Makishima, Kazuo; Uchida, Nagomi
Utilizing four archival X-ray data sets taken with the Hard X-ray Detector onboard Suzaku, timing studies were performed on three magnetars, 1E 1841-045 (observed in 2006), SGR 0501+4516 (2008), and 1RXS J170849.0-400910 (2009 and 2010). Their pulsations were reconfirmed, typically in an energy range of 12-50 keV. The 11.783 s pulses of 1E 1841-04…
Wide binaries and modified gravity (MOG)
Moffat, J. W.
Wide binary stars are used to test the modified gravity called Scalar-Tensor-Vector Gravity or MOG. This theory is based on the additional gravitational degrees of freedom, the scalar field G = GN (1+α), where GN is Newton's constant, and the massive (spin-1 graviton) vector field ϕµ . The wide binaries have …
Multi-Spacecraft Magnetic Field Reconstructions: A Cross-Scale Comparison of Methods
Klein, K. G.; Broeren, T.; TenBarge, J. M.
Space plasma studies frequently use in situ magnetic field measurements taken from many spacecraft simultaneously. A useful data product of these measurements is the reconstructed magnetic field in a volume near the spacecraft observatory. We compare a standard Linear method of computing the magnetic field at arbitrary spatial points to two novel …
Identification of a single plasma parcel during a radial alignment of the Parker Solar Probe and Solar Orbiter
Alexandrova, Olga; Maksimovic, Milan; Démoulin, Pascal +2 more
Configurations in which two spacecraft, such as the Parker Solar Probe (PSP) and Solar Orbiter, are radially aligned provide opportunities for studying the evolution of a single solar wind parcel during so-called plasma line-ups. The most critical part of these studies arguably is the identification of what can be considered the same plasma crossi…
Asteroseismic Inversions for Internal Sound Speed Profiles of Main-sequence Stars with Radiative Cores
Basu, Sarbani; Hekker, Saskia; Christensen-Dalsgaard, Jørgen +3 more
The theoretical oscillation frequencies of even the best asteroseismic models of solar-like oscillators show significant differences from observed oscillation frequencies. Structure inversions seek to use these frequency differences to infer the underlying differences in stellar structure. While used extensively to study the Sun, structure inversi…
Chandra X-Ray Observatory Observations of 13 Fermi LAT Sources
Kargaltsev, Oleg; Yang, Hui; Hare, Jeremy +3 more
In the latest data release from the Fermi Gamma-ray Space Telescope (the 4th Fermi LAT 14 yr Catalog, or 4FGL), more than 50% of the Galactic sources are yet to be identified. We observed 13 unidentified Fermi LAT sources with the Chandra X-Ray Observatory to explore their nature. We report the results of the classification of X-ray sources in the…
PLATO on the shoulders of TESS: analysing mono-transit planet candidates in TESS data as a prior knowledge for PLATO observations
Vines, Jose I.; Piotto, Giampaolo; Kostov, Veselin +9 more
The Transiting Exoplanet Survey Satellite (TESS) and the upcoming mission PLAnetary Transits and Oscillations of stars (PLATO) represent two space-based missions with complementary objectives in the field of exoplanet science. While TESS aims at detecting and characterizing exoplanets around bright and nearby stars on a relative short-period orbit…
Co-moving groups around massive stars in the nuclear stellar disk
Najarro, F.; Nogueras-Lara, F.; Schödel, R. +2 more
Context. Over the last ∼30 Myr, the nuclear stellar disk in the Galactic center has been the most prolific star-forming region of the Milky Way when averaged by volume. Remarkably, the combined mass of the only three clusters present today in the nuclear stellar disk adds up to only ∼10% of the total expected mass of young stars formed in this per…
Cloud-cloud collision in S235: triggered the formation of high-mass stars and young star clusters
Fang, Min; Gao, Yu; Zhang, Shiyu +7 more
We present the analysis of cloud-cloud collision (CCC) process in the Galactic molecular complex S235. Our new CO observations performed with the PMO-13.7 m telescope reveal two molecular clouds, namely the S235-Main and the S235-ABC, with ~4 km s-1 velocity separation. The bridge feature, the possible colliding interface and the comple…
Fast and Robust Noise Background Modeling and Quasiperiodic Oscillation Detection for Astronomical Time Series
Xu, Chang
Spectrum with confidence levels is a commonly used method for quasiperiodic oscillation (QPO) detection, but it is prone to yield false positives for two reasons: poor choice and/or biased modeling of the null hypothesis (or noise background). Motivated by this, we propose a new time-domain maximum-likelihood estimation method, which can quickly a…