Search Publications
Dependence of Stellar Differential Rotation on Effective Temperature and Rotation: An Analysis from Starspot Transit Mapping
Valio, Adriana; Araújo, Alexandre
Stellar rotation is crucial for studying stellar evolution, since it provides information about age, angular momentum transfer, and magnetic fields of stars. In the case of the Sun, due to its proximity, detailed observation of sunspots at various latitudes and longitudes allows a precise estimation of the solar rotation period and its differentia…
Asteroseismology Sheds Light on the Origin of Carbon-deficient Red Giants: Likely Merger Products and Linked to the Li-rich Giants
Zhao, Gang; Campbell, Simon W.; Reddy, Bacham E. +2 more
Carbon-deficient red giants (CDGs) are a peculiar class of stars that have eluded explanation for decades. We aim to better characterize CDGs by using asteroseismology (Kepler, TESS) combined with spectroscopy (APOGEE, LAMOST), and astrometry (Gaia). We discovered 15 new CDGs in the Kepler field, and confirm that CDGs are rare, as they are only 0.…
Properties of Star Formation of the Large Magellanic Cloud As Probed by Young Stellar Objects
Tachihara, Kengo; Kaneda, Hidehiro; Fukui, Yasuo +2 more
We perform a systematic study of the evolutionary stages and stellar masses of young stellar objects (YSOs) in the Large Magellanic Cloud (LMC) to investigate the properties of star formation in the galaxy. There are 4825 sources in our YSO sample, which are constructed by combining the previous studies identifying YSOs in the LMC. Spectral energy…
Optical and Near-infrared Observations of the Distant but Bright "New Year's Burst" GRB 220101A
Fynbo, Johan P. U.; Gao, Xing; Xu, Dong +26 more
High-redshift gamma-ray bursts (GRBs) are useful to probe the early Universe, but only a few candidates have been detected so far. Here, we report the optical and near-infrared observations of the afterglow of a relatively high-redshift event GRB 220101A, which was triggered on New Year's Day of 2022, and therefore referred to as the "New Year's b…
Andromeda's Parachute: Time Delays and Hubble Constant
Dahle, Håkon; Goicoechea, Luis J.; Shalyapin, Vyacheslav N. +1 more
The gravitational lens system PS J0147+4630 (Andromeda's Parachute) consists of four quasar images ABCD and a lensing galaxy. We obtained r-band light curves of ABCD in the 2017-2022 period from monitoring with two 2 m class telescopes. Applying state-of-the-art curve-shifting algorithms to these light curves led to measurements of time delays bet…
Dynamical Response of Solar Wind Charge Exchange Soft X-Ray Emission in Earth's Magnetosphere to the Solar Wind Proton Flux
Ji, Li; Wang, Chi; Liu, Wenhao +5 more
This work studies the dynamic response of solar wind charge exchange (SWCX) soft X-ray emission in the Earth's magnetosphere to the solar wind proton flux. Unlike previous studies that attempted to use complex magnetohydrodynamic models to match the details of observed SWCX of a necessarily limited number of cases, this work focuses on determining…
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): The Warm-envelope Origin of Hot Corinos
Sanhueza, Patricio; Kwon, Woojin; Chen, Huei-Ru Vivien +24 more
Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequent potential prebiotic connection to solar-like planetary systems. Recent surveys have reported an increasing number of detected hot corinos in Class 0/I protostars; however, the relationships between their physical properties a…
Influence of Intermittency on the Energy Transfer Rate of Solar Wind Turbulence
Wang, Xin; Yuan, Zhigang; Huang, Shiyong +2 more
The intermittency in the solar wind turbulence manifests itself in the anisotropic scaling due to the anisotropic spectral index and the intermittent level based on the extended P model. However, the influence of intermittency on the energy transfer rate remains unclear. Here we apply the partial variance of increments method to identify the inter…
Third Epoch HST Imaging of a Nonradiative Shock in the Cygnus Loop Supernova Remnant
Blair, William P.; Raymond, John C.; Sankrit, Ravi
We present new HST/WFC3 optical images of a region in the northeastern part of the Cygnus Loop supernova remnant, which includes a well-studied Balmer-line filament. These data represent the third epoch of HST Hα imaging and a second epoch of [O III] λ5007 imaging of that particular filament. The Hα images were used to measure the proper motions a…
Interpretation of Flat Energy Spectra Upstream of Fast Interplanetary Shocks
Zimbardo, Gaetano; Servidio, Sergio; Wilson, Lynn B., III +6 more
Interplanetary shocks are large-scale heliospheric structures often caused by eruptive phenomena at the Sun, and represent one of the main sources of energetic particles. Several interplanetary (IP) shock crossings by spacecraft at 1 au have revealed enhanced energetic-ion fluxes that extend far upstream of the shock. Surprisingly, in some shock e…