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The Fengyun-3E/Joint Total Solar Irradiance Absolute Radiometer: Instrument Design, Characterization, and Calibration
Zhao, Yan; Fang, Wei; Finsterle, Wolfgang +6 more
The Joint Total Solar Irradiance Monitor (JTSIM) is due to fly onboard the Fengyun-3E spacecraft and aims to measure the Total Solar Irradiance (TSI) in orbit. The instruments on the Fengyun-3E/JTSIM include the Digital Absolute Radiometer (DARA) from the Physikalisch Meteorologisches Observatorium, Davos and World Radiation Center (PMOD/WRC) and …
Pre-explosion Properties of Helium Star Donors to Thermonuclear Supernovae
Schwab, Josiah; Götberg, Ylva; Wong, Tin Long Sunny
Helium star-carbon-oxygen white dwarf (CO WD) binaries are potential single-degenerate progenitor systems of thermonuclear supernovae. Revisiting a set of binary evolution calculations using the stellar evolution code MESA, we refine our previous predictions about which systems can lead to a thermonuclear supernova and then characterize the proper…
Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs
Li, Chengyuan
The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of "simple stellar populations" into the so-called "multiple stellar populations" (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence …
A new search for star forming regions in the southern outer Galaxy
König, C.; Menten, K. M.; Wyrowski, F. +2 more
Context. Star formation in the outer Galaxy is thought to be different from that in the inner Galaxy, as it is subject to different environmental parameters such as metallicity, interstellar radiation field, or mass surface density, which all change with galactocentric radius. Extending our star formation knowledge, from the inner to the outer Gal…
X-ray spectral evolution in an X-ray changing-look AGN NGC 1365 with variable column density
Liu, Hao; Yang, Jun; Wang, Ting-Gui +4 more
X-ray changing-look active galactic nuclei (CL AGNs) are a subpopulation of AGNs, whose line-of-sight column densities increase/decrease within several years. The physical mechanism for the variation of column density is unclear. We reduce the X-ray data from XMM-Newton and NuSTAR observations for a CL AGN NGC 1365 with strong variation of column …
Detecting the intrinsic X-ray emission from the O-type donor star and the residual accretion in a supergiant fast X-ray transient in its faintest state
Salvaterra, R.; Marelli, M.; Sidoli, L. +4 more
We report on the results of an XMM-Newton observation of the supergiant fast X-ray transient (SFXT) IGR J08408-4503 performed in June 2020. The source is composed of a compact object (likely a neutron star) orbiting around an O8.5Ib-II(f)p star, LM Vel. The X-ray light curve shows a very low level of emission, punctuated by a single, faint flare. …
Midsummer Atmospheric Changes in Saturn's Northern Hemisphere from the Hubble OPAL Program
Wong, Michael H.; Hueso, Ricardo; Sánchez-Lavega, Agustín +1 more
Using the Hubble Space Telescope, Saturn was observed in 2018, 2019, and 2020, just after the northern hemisphere summer solstice. Analysis of multispectral imaging data reveals three years of cloud changes associated with a 70° N storm that began in 2018. Additionally, there is an increase in equatorial brightness and perhaps haze optical depth a…
Terahertz Water Masers. II. Further SOFIA/GREAT Detections Toward Circumstellar Outflows, and a Multitransition Analysis
Wyrowski, Friedrich; Menten, Karl M.; Wiesemeyer, Helmut +8 more
Following up on our discovery of terahertz water masers, reported in 2017, we report two further detections of water maser emission at frequencies above 1 THz. Using the GREAT instrument on SOFIA, we have detected emission in the 1.296411 THz 827 - 734 transition of water toward two additional oxygen-rich evolved stars, omicr…
Ground Vibrational State SiO Emission in the VLA BAaDE Survey
Rich, R. M.; Morris, M. R.; Claussen, M. J. +5 more
Using a subsample of the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey of stellar SiO masers, we explore the prevalence and characteristics of 28SiO J = 1 - 0, v = 0 emission. We identify 90 detections of maser, thermal, or composite 28SiO J = 1 - 0, v = 0 emission out of approximately 13,000 candidate spectra from…
X-ray study of Abell 3365 with XMM-Newton
Urdampilleta, I.; Simionescu, A.; Kaastra, J. S. +5 more
We present an X-ray spectral analysis using XMM-Newton/EPIC observations (∼100 ks) of the merging galaxy cluster Abell 3365 (z = 0.093). Previous radio observations suggested the presence of a peripheral elongated radio relic to the east and a smaller radio relic candidate to the west of the cluster center. We find evidence of temperature disconti…