Search Publications
X-Ray Unveiling Events in a z ≈ 1.6 Active Galactic Nucleus in the 7 Ms Chandra Deep Field-South
Trump, Jonathan R.; Brandt, W. N.; Vignali, C. +14 more
We investigate the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening events. In the first event, XID 403 brightened by a factor of >2.5 in ≲6.1 rest-frame days in the observed-frame 0.5-5 keV band. The event lasted for ≈5.0-7.3 days, an…
Gravitational Redshift Detection from the Magnetic White Dwarf Harbored in RX J1712.6-2414
Ishida, Manabu; Hayashi, Takayuki; Mori, Hideyuki +2 more
Gravitational redshift is a fundamental parameter that allows us to determine the mass-to-radius ratio of compact stellar objects, such as black holes, neutron stars, and white dwarfs (WDs). In the X-ray spectra of the close binary system, RX J1712.6-2414, obtained from the Chandra High Energy Transmission Grating observation, we detected signific…
Physical characterization of late-type contact binary systems observed by LAMOST: a comprehensive statistical analysis
Abdel Rahman, H. I.; Darwish, Mohamed
This paper presents a catalog of approximately 1800 Eclipsing W UMa systems (EWs) using parameters from LAMOST, VSX, ZTF and Gaia. Our detailed statistical analysis includes frequency distributions of parameters, confidence intervals, and hypothesis testing to provide deeper insights into the physical properties of this important eclipsing binary …
Inferring the Solar Meridional Circulation Flow Profile by Applying Bayesian Methods to Time-Distance Helioseismology
Jackiewicz, Jason; Herczeg, Aleczander
Mapping the large-scale subsurface plasma flow profile within the Sun has been attempted using various methods for several decades. One such flow in particular is the meridional circulation, for which numerous studies have been published. However, such studies often show disagreement in structure. In an effort to constrain the flow profile from th…
GAIA Arguments for and against a Hypothetical Sun Companion
Malkov, O. Yu.
The hypothesis that the Sun is a component of a binary star system has been around for about a hundred years. Assumptions about the nature of the companion continue to be published as new observational data become available. The paper shows that the results of the work of the Gaia space observatory impose certain restrictions on the nature and loc…
Two Warm Super-Earths Transiting the Nearby M Dwarf TOI-2095
Kostov, Veselin B.; Powell, Brian P.; Barclay, Thomas +56 more
We report the detection and validation of two planets orbiting TOI-2095 (TIC 235678745). The host star is a 3700 K M1V dwarf with a high proper motion. The star lies at a distance of 42 pc in a sparsely populated portion of the sky and is bright in the infrared (K = 9). With data from 24 sectors of observation during Cycles 2 and 4 of the Transiti…
An X-rays-to-radio investigation of the nuclear polarization from the radio-galaxy Centaurus A
Wu, Kinwah; Lopez-Rodriguez, Enrique; Marin, Frédéric +5 more
Centaurus A is one of the closest radio galaxies to Earth. Its proximity allowed us to extensively study its active galactic nucleus but the core emission mechanism remains elusive because of local strong dust and gas obscuration. The capability of polarimetry to shave-off contaminating emission has been exploited without success in the near-infra…
Resolving Ambiguities in SHARAD Data Analysis Using High-Resolution Digital Terrain Models
Kofman, Wlodek; Herique, Alain; Zine, Sonia +2 more
The SHAllow RADar (SHARAD) onboard Mars Reconnaissance Orbiter (MRO) is a 20 MHz Synthetic Aperture Radar (SAR) that probes the first hundreds of meters of the Martian subsurface. In order to interpret the detection of subsurface interfaces with ground penetrating radars, simulations using Digital Terrain Models (DTM) are necessary. This methodolo…
Geocoronal Solar Wind Charge Exchange Process Associated With the 2006-December-13 Coronal Mass Ejection Event
Toriumi, Shin; Mitsuda, Kazuhisa; Yamasaki, Noriko Y. +1 more
We report the discovery of a geocoronal solar wind charge exchange (SWCX) event corresponding to the well-known 2006 December 13th coronal mass ejection (CME) event. Strong evidence for the charge exchange origin of this transient diffuse emission is provided by prominent non-thermal emission lines at energies of O7+, Ne9+, M…
First detection of deuterated methylidyne (CD) in the interstellar medium
Wyrowski, Friedrich; Menten, Karl M.; Jacob, Arshia M. +1 more
While the abundance of elemental deuterium is relatively low (D/H ~ a few ×10−5), orders of magnitude higher D/H abundance ratios have been found for many interstellar molecules, enhanced by deuterium fractionation. In cold molecular clouds (T < 20 K), deuterium fractionation is driven by the H2D+ ion, whereas a…