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A Silent Revolution in Fundamental Astrophysics
Bakış, Volkan; Bilir, Selçuk; Soydugan, Faruk +2 more
Arbitrariness in the zeropoint of bolometric corrections is a paradigm that is nearly a century old and leads to two more paradigms. "Bolometric corrections must always be negative," and "the bolometric magnitude of a star ought to be brighter than its V magnitude". Both were considered valid before the IAU 2015 General Assembly Resolution B2, a r…
An Imaging Search for Post-main-sequence Planets of Sirius B
Lucas, Miles; Ruane, Garreth; Bottom, Michael +1 more
We present deep imaging of Sirius B, the closest and brightest white dwarf, to constrain post-main-sequence planetary evolution in the Sirius system. We use Keck/NIRC2 in L' band (3.776 µm) across three epochs in 2020 using the technique of angular differential imaging. Our observations are speckle-limited out to 1 au and background-limited …
The First High-contrast Images of X-Ray Binaries: Detection of Candidate Companions in the γ Cas Analog RX J1744.7-2713
Fabian, A. C.; Gandhi, P.; Mawet, D. +17 more
X-ray binaries provide exceptional laboratories for understanding the physics of matter under the most extreme conditions. Until recently, there were few, if any, observational constraints on the circumbinary environments of X-ray binaries at ~100-5000 au scales. It remains unclear how the accretion onto the compact objects or the explosions givin…
An Infrared View of the Obscured AGN Environment in NGC 4945
Schirmer, M.; Díaz, R. J.; Agüero, M. P. +4 more
NGC 4945 harbors one of the nearest active galactic nuclei (AGNs), which allows us to reach high spatial resolution with current observational facilities. The Seyfert 2 nucleus is deeply obscured by an edge-on disk with A V ~ 14, requiring infrared observations to study circumnuclear structures and the interstellar medium. In this wor…
Precise Positions of Five Major Uranian Satellites During 2008-2014 Based on Gaia EDR3
Cheng, X.; Zhang, H. Y.; Yan, D. +4 more
The five major Uranian satellites (Ariel, Umbriel, Titania, Oberon, and Miranda) were observed by a 1.56 m telescope at Sheshan Station of Shanghai Astronomical Observatory during 2008-2014 and a total of 1915 positions of these five satellites were presented in this paper. Since all five satellites are close to Uranus, their positions are affecte…
Revisiting Kepler Transiting Systems: Unvetting Planets and Constraining Relationships among Harmonics in Phase Curves
Shporer, Avi; de Wit, Julien; Wong, Ian +1 more
Space-based photometric missions widely use statistical validation tools for vetting transiting planetary candidates, particularly when other traditional methods of planet confirmation are unviable. In this paper, we refute the planetary nature of three previously validated planets-Kepler-854 b, Kepler-840 b, and Kepler-699 b-and possibly a fourth…
Apsidal Motion and Physical Parameters in the Eclipsing System V490 Sct
Volkov, Igor M.; Kravtsova, Alexandra S.
We report long-term UBVRIR c I c photometry of the highly eccentric 12.04 day detached eclipsing binary V490 Sct (V = 13.1, B9.5+A0, e = 0.40), which we use to determine its relative and absolute parameters. The absolute masses, radii, and temperatures are M A = 2.33 ± 0.07 M⊙, R A = 1…
The Open Cluster Chemical Abundances and Mapping Survey. V. Chemical Abundances of CTIO/Hydra Clusters Using The Cannon
Donor, John; Frinchaboy, Peter M.; Chojnowski, S. D. +2 more
Open clusters are key chemical and age tracers of Milky Way evolution. While open clusters provide significant constraints on galaxy evolution, their use has been limited due to discrepancies in measuring abundances from different studies. We analyze medium-resolution (R ~ 19,000) Cerro Tololo Inter-American Observatory/Hydra spectra of giant star…
On the Unusual Variability of 2MASS J06195260-2903592: A Long-lived Disk around a Young Ultracool Dwarf
Magnier, Eugene A.; Gaidos, Eric; Shappee, Benjamin J. +11 more
We present the characterization of the low-gravity M6 dwarf 2MASS J06195260-2903592, previously identified as an unusual field object based on its strong IR excess and variable near-IR spectrum. Multiple epochs of low-resolution (R ≈ 150) near-IR spectra show large-amplitude (≈0.1-0.5 mag) continuum variations on timescales of days to 12 yr, unlik…
Mass-Velocity Dispersion Relation by Using the Gaia Data and Its Effect on Interpreting Short-duration and Degenerate Microlensing Events
Sajadian, Sedighe; Rahvar, Sohrab; Kazemian, Fatemeh
Gravitational microlensing, the lensing of stars in the Milky Way with other stars, has been used for exploring compact dark matter objects, exoplanets, and black holes. The duration of microlensing events, the so-called Einstein crossing time, is a function of distance, mass, and velocities of lens objects. Lenses with different ages and masses m…