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First Report of a Solar Energetic Particle Event Observed by China's Tianwen-1 Mission in Transit to Mars
Zhao, Lingling; Sun, Zhiyu; Yu, Yuhong +15 more
Solar energetic particles (SEPs) associated with flares and/or coronal mass ejection (CME)-driven shocks can impose acute radiation hazards on space explorations. To measure energetic particles in near-Mars space, the Mars Energetic Particle Analyzer (MEPA) instrument on board China's Tianwen-1 (TW-1) mission was designed. Here, we report the firs…
Relationship between Total Solar Irradiance and Magnetic Flux during Solar Minima
Lean, Judith L.; Marchenko, Sergey V.; DeLand, Matthew T.
What drives the small total solar irradiance (TSI) changes of ~50-100 parts per million (compared with >1000 ppm solar-cycle amplitudes) during a deep solar minimum, i.e., in the practical absence of detectable sunspots and long-lasting active regions? We consider the epoch 2008 June-October and investigate multiple data sets (TSI; various Mg I…
A Very Long Baseline Array Trigonometric Parallax for RR Aql and the Mira Period-Luminosity Relation
Sun, Yan; Reid, Mark J.; Zhang, Bo +4 more
We report Very Long Baseline Array observations of 22 GHz H2O and 43 GHz SiO masers toward the Mira variable RR Aql. By fitting the SiO maser emission to a circular ring, we estimate the absolute stellar position of RR Aql and find agreement with Gaia astrometry to within the joint uncertainty of ≈1 mas. Using the maser astrometry we me…
On the Evolution of Rotational Modulation Amplitude in Solar-mass Main-sequence Stars
Masuda, Kento
We investigate the relation between rotation periods P rot and photometric modulation amplitudes R per for ≈4000 Sun-like main-sequence stars observed by Kepler, using P rot and R per from McQuillan et al., effective temperature T eff from LAMOST DR6, and parallax data from Gaia EDR3. As has b…
Radio Emission from Binary Ultracool Dwarf Systems
Kao, Melodie M.; Pineda, J. Sebastian
Well-characterized binary systems will provide valuable opportunities to study the conditions that are necessary for the onset of both auroral and nonauroral magnetospheric radio emission in the ultracool dwarf regime. We present new detections of nonauroral "quiescent" radio emission at 4-8 GHz of the three ultracool dwarf binary systems GJ 564 B…
Discovery of Nine Super Li-rich Unevolved Stars from the LAMOST Survey
Wang, L.; Shi, J. -R.; Zhou, Y. -T. +7 more
Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars with A(Li) > 3.8 dex. These objects show unusually high levels of lithium abundances, up to three times higher than the meteoritic value of 3.3 dex, which ind…
Spectral Evolution of Dark Asteroid Surfaces Induced by Space Weathering over a Decade
Hasegawa, Sunao; Marsset, Michaël; Im, Myungshin +20 more
The surfaces of airless bodies like asteroids in the solar system are known to be affected by space weathering. Experiments simulating space weathering are essential for studying the effects of this process on meteorite samples, but the problem is that the time spent to reproduce space weathering in these experiments is billions of times shorter t…
Isolated Massive Star Formation in G28.20-0.05
Law, Chi-Yan; Garay, Guido; Mardones, Diego +9 more
We report high-resolution 1.3 mm continuum and molecular line observations of the massive protostar G28.20-0.05 with Atacama Large Millimeter/submillimeter Array. The continuum image reveals a ring-like structure with 2000 au radius, similar to morphology seen in archival 1.3 cm Very Large Array observations. Based on its spectral index and associ…
KIC 2857323: A Double-mode High-amplitude δ Scuti Star with Amplitude Decline of the First Overtone Mode
Esamdin, Ali; Yang, Tao-Zhi; Zuo, Zhao-Yu +2 more
We investigate the pulsating behavior of KIC 2857323 using high-precision observations from the Kepler mission. Fourier analysis of 4 yr time-series data reveals five independent frequencies for the light variation. Among them, two strong frequencies f 1 and f 3 with a period ratio of 0.774 identify this star as a double-mode…
Gamma-Ray Diagnostics of r-process Nucleosynthesis in the Remnants of Galactic Binary Neutron-star Mergers
Katsuda, Satoru; Terada, Yukikatsu; Bamba, Aya +4 more
We perform a full nuclear-network numerical calculation of the r-process nuclei in binary neutron-star mergers (NSMs), with the aim of estimating gamma-ray emissions from the remnants of Galactic NSMs up to 106 yr old. The nucleosynthesis calculation of 4070 nuclei is adopted to provide the elemental composition ratios of nuclei with an…