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What can be learnt from a highly informative X-ray occultation event in NGC 6814? A marvellous absorber
Kang, Jia-Lai; Wang, Jun-Xian; Fu, Shu-Qi
A unique X-ray occultation event in NGC 6814 during an XMM-Newton observation in 2016 has been reported, providing useful information of the absorber and the corona. We revisit the event with the aid of the hardness ratio (HR)-count rate (CR) plot and comparison with two other absorption-free XMM exposures in 2009 and 2021. NGC 6814 exhibits a cle…
Torque reversal and cyclotron absorption feature in HMXB 4U 1538-522
Jain, Chetana; Dutta, Anjan; Sharma, Prince
We present a comprehensive timing and spectral analysis of the HMXB 4U 1538-522 by using the Nuclear Spectroscopic Telescope Array (NuSTAR) observatory data. Using three archived observations made between 2019 and 2021, we have detected ~ 526 s coherent pulsations up to 60 keV. We have found an instantaneous spin-down rate of $\dot{P} = 6.6_{-6.0}…
To Be or Not to Be: Alicante-8, a Cluster or Not?
Rejkuba, M.; Negueruela, I.; Ivanov, V. D. +3 more
Recent surveys have uncovered new young massive clusters that host dozens of red supergiants (RSGs) near the inner Galaxy. However, many of them have still not been fully studied. Using Very Large Telescope/X-shooter near-infrared spectra, we present the first radial velocity analysis for the putative members of the candidate RSG cluster Alicante-…
Statistical distribution of mirror-mode-like structures in the magnetosheaths of unmagnetized planets - Part 2: Venus as observed by the Venus Express spacecraft
Stenberg Wieser, Gabriella; Futaana, Yoshifumi; Mazelle, Christian +7 more
In this series of papers, we present statistical maps of mirror-mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on extreme ultraviolet (EUV) s…
Systematics of planetary ephemeris reference frames inferred from pulsar timing astrometry
Liu, N.; Zhu, Z.; Liu, J. -C. +2 more
Aims: This study aims to investigate the systematic errors in planetary ephemeris reference frames through pulsar timing observations.
Methods: We used the published data sets from several pulsar timing arrays and performed timing analyses for each pulsar using different planetary ephemerides retrieved from the Jet Propulsion Laboratory'…
Weighing the Darkness. III. How Gaia Could, but Probably Will Not, Astrometrically Detect Free-floating Black Holes
Andrews, Jeff J.
The gravitational pull of an unseen companion to a luminous star is well known to cause deviations to the parallax and proper motion of a star. In a previous paper in this series, we argue that the astrometric mission Gaia can identify long-period binaries by precisely measuring these arcs. An arc in a star's path can also be caused by a flyby: a …
The Potential of Detecting Nearby Terrestrial Planets in the HZ with Different Methods
Hui-Gen, Liu; Qiao-Yang, Hao; Shen-Wei, Zhou
Terrestrial planets in the habitable zone (hereafter HZ) around nearby stars are of great interest and provide a good sample to characterize their habitability. In this paper, we collect a nearby star catalog within 20 pc according to the Gaia Catalog of Nearby Stars, complete the physical parameters of the stars, and select stars that are not bro…
Kinematical and ellipsoidal properties of K dwarfs in the solar neighborhood of the Gaia era
Elsanhoury, W. H.; Al-Johani, Amnah S.
The study reports velocity ellipsoid parameters including the kinematical properties of K dwarf stars. Herein, two samples of K dwarf stars are presented with the solar neighborhood ( pc) for high (; 106 points) and low galactic latitudes (; 199 points). We calculated spatial velocities (, , and ; km s) along the galactic coordinates and the veloc…
A race against the clock: Constraining the timing of cometary bombardment relative to Earth's growth
Nesvorný, David; Avice, Guillaume; Raymond, Sean N. +3 more
Comets are considered a potential source of inner solar system volatiles, but the timing of this delivery relative to that of Earth's accretion is still poorly understood. Measurements of xenon isotopes in comet 67P/Churyumov-Gerasimenko revealed that comets partly contributed to the Earth's atmosphere. However, there is no conclusive evidence of …
Investigating the Impact of Metallicity on Star Formation in the Outer Galaxy. I. VLT/KMOS Survey of Young Stellar Objects in Canis Major
Herczeg, Gregory J.; Tabone, Benoît; Fischer, William J. +9 more
The effects of metallicity on the evolution of protoplanetary disks may be studied in the outer Galaxy where the metallicity is lower than in the solar neighborhood. We present the VLT/KMOS integral field spectroscopy in the near-infrared of ~120 candidate young stellar objects (YSOs) in the CMa-ℓ224 star-forming region located at a Galactocentric…