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Investigating Ionization in the Intergalactic Medium
Borthakur, Sanchayeeta; Koplitz, Brad; Ramesh, Anjali
The intergalactic medium (IGM) contains >50% of the baryonic mass of the Universe, yet the mechanisms responsible for keeping the IGM ionized have not been fully explained. Hence, we investigate ion abundances from the largest blind QSO absorption catalog for clouds that show C IV, N V, and O VI simultaneously. The wavelength range of present U…
A robust automated machine-learning method for the identification of star clusters in the central region of the Small Magellanic Cloud
Hatzidimitriou, D.; Zezas, A.; Antoniou, V. +3 more
Aims: We developed a cluster-detection method based on the code DBSCAN to identify star clusters in the central region of the Small Magellanic Cloud (SMC).
Methods: Two approaches were used to determine the values of the free parameters of DBSCAN. They agree well with each other and can be used in the fields that are studied without any …
A photometric study of a total-eclipse contact binary V458 Mon
Zhu, Liying; Matekov, Azizbek; Zubairi, Ahmed Waqas +3 more
We present light curve solution of V458 Mon firstly by using the Wilson-Devinney code. The total eclipse and deep minima of the light curves of V458 Monenable us to determine reliable orbital parameters of the binary system. The solution suggests that V458 Monis a low mass ratio binary system with about 0.2 possessing a moderate degree of contact.…
Lyman Limit System with O VI in the Circumgalactic Environment of a Pair of Galaxies
Wendt, Martin; Muzahid, Sowgat; Narayanan, Anand +3 more
We report on the analysis of a multiphase Lyman limit system (LLS) at z = 0.39047 identified toward the background quasar FBQS J0209–0438. The O VI doublet lines associated with this absorber have a different profile from the low-ionization metals and H I. Ly α has a very broad H I (b ≈ 150 km s‑1) component well-aligned with one of the…
Pixel-level Terrain Processing of the Martian Surface from Moderate Resolution Images of Tianwen-1
Liu, Dingxin; Yan, Wei; Liu, Jianjun +3 more
The moderate-resolution camera (MoRIC) of the Tianwen-1 orbiter, China's first Mars exploration mission, is a frame-imaging scheme color camera. However, generating a precise digital elevation model (DEM) from these images faces challenges due to the presence of featureless and repetitive regions on the Martian surface. Traditional photogrammetric…
A Low Albedo, Thin, Resistant Unit in Oxia Planum, Mars: Evidence for an Airfall Deposit and Late-Stage Groundwater Activity at the ExoMars Rover Landing Site
Fawdon, P.; Grindrod, P. M.; Davis, J. M. +2 more
Oxia Planum, Mars, is the future landing site of the ExoMars Rosalind Franklin rover mission, which will search for preserved biosignatures in a phyllosilicate-bearing unit. Overlying the mission-important phyllosilicate-bearing rocks is a dark, capping unit—known here as the Low albedo, Thin, Resistant (LTR) unit—which may have protected the phyl…
Flare-accelerated Electrons in the Kappa Distribution from X-Ray Spectra with the Warm-target Model
Kontar, Eduard P.; Luo, Yingjie; Bhattacharjee, Debesh
X-ray observations provide important and valuable insights into the acceleration and propagation of nonthermal electrons during solar flares. Improved X-ray spectral analysis requires a deeper understanding of the dynamics of energetic electrons. Previous studies have demonstrated that the dynamics of accelerated electrons with a few thermal speed…
Amplitude and phase changes in TESS photometry of five short period weak-lined T Tauri stars
Koen, C.
The statistical technique 'Complex Demodulation' (CDM) is used to track the amplitude and phase changes of periodicities in five naked T Tauri stars. The periodicities are most likely caused by dark spots on the stellar surfaces, which are rotated into and out of view. Two of the stars (CD-56 1438, CD-72 248) show two independent periodicities, pr…
Magnetic Fields in a Sample of Planet-hosting M Dwarf Stars from Kepler, K2, and TESS Observed by APOGEE
Wanderley, Fábio; Cunha, Katia; Smith, Verne V. +8 more
Stellar magnetic fields have a major impact on space weather around exoplanets orbiting low-mass stars. From an analysis of Zeeman-broadened Fe I lines measured in near-infrared SDSS/APOGEE spectra, mean magnetic fields are determined for a sample of 29 M dwarf stars that host closely orbiting small exoplanets. The calculations employed the radiat…
Possible influence of Martian surface mineralogy on the detectability of atmospheric trace gases - mid-infrared simulation results
Błęcka, Maria I.
The paper focuses on the influence of the optical properties of Martian surface minerals on remotely detected gaseous components of the Martian atmosphere, when the spectrometer receives a combined signal from the Martian soil and atmosphere. Our considerations are primarily concerned with the detectability of methane, but the problem may also app…