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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…
The 3D Galactocentric Velocities of Kepler Stars: Marginalizing Over Missing Radial Velocities
Angus, Ruth; Foreman-Mackey, Daniel; Bedell, Megan +3 more
Precise Gaia measurements of positions, parallaxes, and proper motions provide an opportunity to calculate 3D positions and 2D velocities (i.e., 5D phase-space) of Milky Way stars. Where available, spectroscopic radial velocity (RV) measurements provide full 6D phase-space information, however there are now and will remain many stars without RV me…
Coronal and Chromospheric Emission in A-type Stars
Robrade, J.; Schneider, P. C.; Wolk, Scott J. +3 more
Cool stars on the main sequence generate X-rays from coronal activity, powered by a convective dynamo. With increasing temperature, the convective envelope becomes smaller and X-ray emission fainter. We present Chandra/HRC-I observations of four single stars with early A spectral types. Only the coolest star of this sample, τ 3 Eri (T <…
WASP-35 and HAT-P-30/WASP-51: Reanalysis using TESS and Ground-based Transit Photometry
Wang, Xiaobin; Gu, Shenghong; Sun, Leilei +3 more
High-precision transit observations provide excellent opportunities for characterizing the physical properties of exoplanetary systems. These physical properties supply many pieces of information for unvealing the internal structure, external atmosphere, and dynamical history of the planets. We present revised properties of the transiting systems …