Search Publications
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…
Detailed Abundances of Planet-hosting Open Clusters. The Praesepe (Beehive) Cluster
Stassun, Keivan G.; Schuler, Simon C.; Vejar, George
It is not yet fully understood how planet formation affects the properties of host stars, in or out of a cluster; however, abundance trends can help us understand this process. We present a detailed chemical abundance analysis of six stars in Praesepe, a planet-hosting open cluster. Pr0201 is known to host a close-in (period of 4.4 days) giant pla…
Absolute parameters of the three totally-eclipsing WUMa stars NSVS 2443858, NSVS 780649 and V1098 Her
Popov, Velimir; Acerbi, Francesco; Barani, Carlo
We present the first photometric analysis of three totally-eclipsing W UMa binaries, NSVS 2443858, NSVS 780649 and V1098 Her. The absolute astrophysical parameters of the stellar components were determined by means of Gaia distances and light curve solutions. The results show that: (i) Two of the systems, NSVS 2443858 and V1098 Her, are of A subty…
A Gaia-based Photometric and Kinematic Analysis of the Old Open Cluster King 11
Bisht, D.; Yadav, R. K. S.; Vereshchagin, S. V. +5 more
This paper presents an investigation of an old age open cluster King 11 using Gaia's Early Data Release 3 data. Considering the stars with membership probability (Pµ) > 90%, we identified 676 most probable cluster members within the cluster's limiting radius. The mean proper motion for King 11 is determined as: µx
Evidence for Fe Kα line and soft X-ray lag in NGC 7456 ultraluminous X-ray source-1
Markowitz, Alex; Mondal, Samaresh; De Marco, Barbara +1 more
We report the first detection of an Fe Kα line and soft X-ray lag in the ultraluminous X-ray (ULX) source NGC 7456 ULX-1. The XMM-Newton spectra show the presence of the 6.4 keV Fe line at 2.6σ confidence and an upper limit on the FWHM of 32900 km s-1. Assuming that the line arises by reflection from a Keplerian disk, it must…