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Investigation of Rocket Effect in BRC 18 using Gaia EDR3
Ojha, D. K.; Saha, Piyali; Neha, Sharma +1 more
Bright-rimmed clouds (BRCs) are ideal candidates to study radiation-driven implosion mode of star formation as they are potential sites of triggered star formation, located at the edges of HII regions, showing evidence of ongoing star formation processes. BRC 18 is located towards the eastern edge of relatively closer (~400 pc) H II region excited…
Selecting a complete sample of blazars in sub-millimetre catalogues
Bonavera, L.; González-Nuevo, J.; López-Caniego, M. +6 more
The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), which has covered about 642 sq. deg. in five bands from 100 to 500 $\mu \rm m$, allows a blind flux-limited selection of blazars at sub-mm wavelengths. However, blazars constitute a tiny fraction of H-ATLAS sources and therefore identifying them is not a trivial task. Using the data…
Investigating the nature and properties of MAXI J1810-222 with radio and X-ray observations
Pinto, C.; Motta, S. E.; Segreto, A. +10 more
We present results from radio and X-ray observations of the X-ray transient MAXI J1810-222. The nature of the accretor in this source has not been identified. In this paper, we show results from a quasi-simultaneous radio and X-ray monitoring campaign taken with the Australia Telescope Compact Array, the Neil Gehrels Swift Observatory X-ray Telesc…
Spectroscopic analysis of BPS CS 22940-0009: connecting evolved helium stars
Jeffery, C. S.; Woolf, V. M.; Snowdon, E. J. +1 more
BPS CS 22940-0009 is a helium-rich B-star that shares characteristics with both helium-rich B subdwarfs and extreme helium stars. The optical spectrum of BPS CS 22940-0009 has been analysed from SALT observations. The atmospheric parameters were found to be $T_{\rm eff} = 34\, 970 \pm 370$ K, $\log g/{\rm cm\, s^{-2}} = 4.79 \pm 0.17$, nH
Improved binary solution for the gamma-ray binary 1FGL J1018.6-5856
Monageng, I. M.; van Soelen, B.; Chernyakova, M. +4 more
The gamma-ray binary 1FGL J1018.6-5856 consists of an O6V((f)) type star and an unknown compact object, and shows orbitally modulated emission from radio to very high energy gamma rays. The X-ray light curve shows a maximum around the same phase as the GeV emission, but also a secondary maximum between phases ϕ = 0.2 and 0.6. A clear solution to t…
Tracing Milky Way substructure with an RR Lyrae hierarchical clustering forest
Mahabal, Ashish A.; Rebbapragada, Umaa; Cook, Brian T. +6 more
RR Lyrae variable stars have long been reliable standard candles used to discern structure in the Local Group. With this in mind, we present a routine to identify groupings containing a statistically significant number of RR Lyrae variables in the Milky Way environment. RR Lyrae variable groupings, or substructures, with potential Galactic archaeo…
Orbital solution and dynamical masses for the nearby binary system GJ 67 AB
Torres, Guillermo
We report spectroscopic observations of the nearby, 19.5-yr binary system GJ 67AB spanning more than 35 yr. We carry out a global orbital solution combining our radial-velocity measurements with others from the literature going back more than a century, and with all other available astrometric observations. The latter include measurements of the r…
Mass assembly history of dark matter haloes in the light of H0 tension
Kameli, Hamed; Baghram, Shant
The Hubble tension may introduce a new course of action to revise the standard Lambda cold dark matter (ΛCDM) model to unravel dark energy and dark matter physics. The Hubble parameter can be reconstructed by late-time observations of the background evolution model independently. We relate the reconstructed Hubble parameter to the structure format…
Understanding the physical state of hot plasma formed through stellar wind collision in WR140 using high-resolution X-ray spectroscopy
Hamaguchi, Kenji; Miyamoto, Asca; Sugawara, Yasuharu +5 more
We analyse a series of XMM-Newton RGS data of the binary Wolf-Rayet star WR140 that encompasses one entire orbit. We find that the RGS detects X-rays from optically thin thermal plasma only during orbital phases when the companion O star is on the near side of the WR star. Although such X-rays are believed to be emitted from the shock cone formed …
Searching for giant planets in the outer Solar system with far-infrared all-sky surveys
Serjeant, Stephen; Sedgwick, Chris
We have explored a method for finding giant planets in the outer Solar system by detecting their thermal emission and proper motion between two far-infrared all-sky surveys separated by 23.4 yr, taken with the InfraRed Astronomical Satellite (IRAS) and the AKARI Space Telescope. An upper distance limit of about 8000 AU is given by both the sensiti…