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A study of the Czernik 2 and NGC 7654 open clusters using CCD UBV photometric and Gaia EDR3 data
Paunzen, E.; Bilir, S.; Ak, T. +5 more
We analysed the open clusters Czernik 2 and NGC 7654 using CCD UBV photometric and Gaia Early Data Release 3 (EDR3) photometric and astrometric data. Structural parameters of the two clusters were derived, including the physical sizes of Czernik 2 being
Deciphering the Deep Origin of Active Regions via Analysis of Magnetograms
McIntosh, Scott W.; Chatterjee, Subhamoy; Dikpati, Mausumi +5 more
In this work, we derive magnetic toroids from surface magnetograms by employing a novel optimization method, based on the trust region reflective algorithm. The toroids obtained in this way are combinations of Fourier modes (amplitudes and phases) with low longitudinal wavenumbers. The optimization also estimates the latitudinal width of the toroi…
Investigating the delay between dust radiation and star-formation in local and distant quenching galaxies
Elbaz, D.; Ciesla, L.; Buat, V. +3 more
We investigate the timescale over which the infrared (IR) luminosity decreases after a complete and rapid quenching of star formation using observations of local and high-redshift galaxies. From spectral energy distribution modelling, we derive the time since quenching of a subsample of 14 galaxies from the Herschel Reference Survey that suffer fr…
Probing the Atmospheric Cl Isotopic Ratio on Mars: Implications for Planetary Evolution and Atmospheric Chemistry
Vandaele, Ann Carine; Aoki, Shohei; Liuzzi, Giuliano +22 more
Following the recent detection of HCl in the atmosphere of Mars by ExoMars/Trace Gas Orbiter, we present here the first measurement of the 37Cl/35Cl isotopic ratio in the Martian atmosphere using a set of Nadir Occultation for MArs Discovery (NOMAD) observations. We determine an isotopic anomaly of −6 ± 78‰ compared to Earth …
Precise Masses, Ages, and Orbital Parameters of the Binary Systems HIP 11352, HIP 70973, and HIP 72479
Al-Wardat, M. A.; Al-Tawalbeh, Y. M.; Hussein, A. M. +7 more
In this work, the orbital elements are improved and the total masses of the three close visual binary systems CVBSs: HIP 11352, HIP 70973, and HIP 72479 are precisely calculated. The calculations were performed based on an assessment of the latest Gaia DR2 and Hipparcos trigonometric parallax measurements. The morphology and kinematics of orbits a…
Speckle Imaging Characterization of Radial Velocity Exoplanet Systems
Henry, Gregory W.; Kane, Stephen R.; Howell, Steve B. +10 more
We conducted speckle imaging observations of 53 stellar systems that were members of long-term radial velocity (RV) monitoring campaigns and exhibited substantial accelerations indicative of planetary or stellar companions in wide orbits. Our observations were made with blue and red filters using the Differential Speckle Survey Instrument at Gemin…
Modes of a stellar system I: Ergodic systems
Binney, James; Lau, Jun Yan
The excursions of star clusters and galaxies around statistical equilibria are studied. For a stable ergodic model Antonov's Hermitian operator on six-dimensional phase space has the normal modes as its eigenfunctions. The excitation energy of the system is just the sum of the (positive) energies associated with each normal mode. Formulae are give…
GECKO Optical Follow-up Observation of Three Binary Black Hole Merger Events: GW190408_181802, GW190412, and GW190503_185404
Lee, Chung-Uk; Kim, Seung-Lee; Im, Myungshin +12 more
We present optical follow-up observation results of three binary black hole merger (BBH) events, GW190408_181802, GW190412, and GW190503_185404, which were detected by the Advanced LIGO and Virgo gravitational wave (GW) detectors. Electromagnetic (EM) counterparts are generally not expected for BBH merger events. However, some theoretical models s…
From Formation to Disruption: Observing the Multiphase Evolution of a Solar Flare Current Sheet
Chitta, L. P.; Cheng, X.; Priest, E. R.
A current sheet, where magnetic energy is liberated through reconnection and converted to other forms, is thought to play the central role in solar flares, the most intense explosions in the heliosphere. However, the evolution of a current sheet and its subsequent role in flare-related phenomena such as particle acceleration is poorly understood. …
Extreme Variability of the V488 Persei Debris Disk
Rieke, G. H.; Gáspár, András; Melis, Carl +1 more
V488 Persei is the most extreme debris disk known in terms of the fraction of the stellar luminosity it intercepts and reradiates. The infrared output of its disk is extremely variable, similar in this respect to the most variable disk known previously, that around ID8 in NGC 2547. We show that the variations are likely to be due to collisions of …