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Discovery of an X-Ray Photoionized Optical Nebula and a Radio Nebula Associated with the ULX NGC 4861 X-1
Liu, Jifeng; Gong, Hang; Urquhart, Ryan +5 more
We have conducted long-slit spectroscopic observations and analyzed archival radio data for the ultraluminous X-ray source (ULX) NGC 4861 X-1. Our spectral line analysis unveils NGC 4861 X-1 as the fourth ULX situated within an X-ray photoionized nebula, following three previous findings made approximately two decades ago. Remarkably, we discover …
X-Ray and Optical Observations of the Young M Dwarf Dipper Star TIC 234284556
Montet, Benjamin T.; Feinstein, Adina D.; Poppenhaeger, Katja +2 more
We observed TIC 234284556 in X-rays and in the optical with XMM-Newton to study the recurring dip previously seen in TESS observations. The dip did not appear during our observation. We detect X-ray flares and anti-correlated rotational modulation in X-rays and in the optical.
Estimation of the Electron Density in the Near 3-4 RE Magnetosphere Based on the Measurement of the Interball-2 Satellite Potential
Smirnova, N. F.; Stanev, G.
A new method is proposed for determining the electron density in rarefied plasma, based on simultaneous measurements of the Interball-2 satellite potential using IESP-2 (electric field instrument) and KM-7 (electron temperature sensor) probe devices. This makes it possible to estimate the photoelectron current density based on a procedure proposed…
Observational evidence of instability phenomena related to open star clusters based on Gaia data
Kovaleva, D. A.
The vast amount of high-quality astrometric and photometric data from Gaia space mission opened new prospects in the investigation of the population of galactic star clusters. In particular, a number of observational evidence have emerged in relation to the phenomena of instability that previously were mainly predicted by dynamical simulations. Th…
Observations of Gaia Microlensing Events in Abastumani
Kvernadze, T.; Kvaratskhelia, O.; Kozlov, V.
Gaia is now one of the most successful and leading transient space mission. It discovers nearly 2000 objects annually from all over the sky, down to about 20 mag, covering all possible classes of transients from supernovae and cataclismic variables to rare phenomena like microlensing events or pair-instability supernovae. The long time baseline of…
A multiwavelength study of the IRAS 23139+5939 (G111.256-0.770) star-forming site and its relation to Sh2-157
Tapia, Mauricio; Persi, Paolo
The far-infrared source IRAS 23139+5939 (G111.25-0.77) is a well-studied massive star-forming region at the centre of a dense molecular clump. It is associated with a low-luminosity and variable methanol maser, a number of water maser clusters, and several compact H II regions. We present new sub-arcsec-resolution broad- and narrow-band near- and …
Keck near-infrared detections of Mab and Perdita
de Pater, Imke; Molter, Edward M.; Moeckel, Chris
We report the first near-infrared detection of Uranus's tiny moon Mab, the presumed source of the blue and diffuse µ ring, using the NIRC2 instrument at Keck Observatory. The detection was permitted by an updated shift-and-stack procedure allowing us to integrate on Mab as it moved across the detector in 23 separate exposures taken over ∼2 h…
Planetary Nebulae catalogue with Gaia EDR3
Dafonte, C.; González-Santamaría, I.; Manteiga, M. +2 more
We have created a new Planetary Nebulae (PNe) catalogue by using astrometric and photometric data from Gaia EDR3. Firstly, we have developed an algorithm that selects the most reliable source from EDR3 to be the Central Star (CS) of each PN, among all sources in the neighbourhood of them. This algorithm considers both the angular distance to PN co…
Possible optical counterparts of ULXs in NGC 1672
Sonbas, Eda; Allak, Sinan; Akyuz, Aysun +1 more
In this study, we use archival data from Hubble Space Telescope (HST), Chandra, XMM‑Newton, and Swift‑XRT, to probe the nature of 9 (X1‑X9) candidate ultraluminous X‑ray sources (ULXs) in NGC 1672. Our study focuses on using the precise source positions obtained via improved astrometry based on Chandra and HST observations to search for and identi…
The Force-freeness of the Solar Photosphere: Revisit with New Approach and Large Data Sets
Zhang, Mei; Zhang, Haocheng
Although it is generally believed that the solar photosphere is not magnetically force-free owing to its high plasma β, the estimations of force-freeness using observed magnetograms have produced disputable results. Some studies confirmed that the photosphere is largely not force-free whereas some authors argued that the photosphere is not far awa…