Search Publications
Optical Night Sky Brightness Measurements from the Stratosphere
Jauzac, Mathilde; Sivanandam, Suresh; Tam, Sut-Ieng +27 more
This paper presents optical night sky brightness measurements from the stratosphere using CCD images taken with the Super-pressure Balloon-borne Imaging Telescope (SuperBIT). The data used for estimating the backgrounds were obtained during three commissioning flights in 2016, 2018, and 2019 at altitudes ranging from 28 to 34 km above sea level. F…
A Multiwavelength Study of the Cool Core Cluster MACS J1447.4+0827
von der Linden, A.; Hlavacek-Larrondo, J.; Allen, S. W. +8 more
Clusters of galaxies are outstanding laboratories for understanding the physics of supermassive black hole (SMBH) feedback. Here we present the first Chandra, Karl G. Jansky Very Large Array, and Hubble Space Telescope analysis of MACS J1447.4+0827 (z = 0.3755), one of the strongest cool core clusters known, in which extreme feedback from its cent…
Spectroscopic Determination of Stellar Parameters and Oxygen Abundances for Hyades/Field G-K Dwarfs
Honda, Satoshi; Takeda, Yoichi
It has been suggested that Fe abundances of K dwarfs derived from Fe I and Fe II lines show considerable discrepancies, and oxygen abundances determined from high-excitation O I 7771-5 triplet lines are appreciably overestimated (the problem becoming more serious toward lower Teff), which, however, has not yet been widely confirmed. Wit…
Intrinsic Color Indices of Early-type Dwarf Stars
Jiang, Biwei; Yuan, Haibo; Deng, Dingshan +2 more
Early-type stars are short lived and scarce in comparison with other types. Based on the recently released catalogs of early-type stars from the largest Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectroscopic survey, the intrinsic colors of the stars with effective temperature up to 32,000 K are determined for the bands from ultrav…
π Earth: A 3.14 day Earth-sized Planet from K2's Kitchen Served Warm by the SPECULOOS Team
Triaud, Amaury H. M. J.; Fulton, Benjamin J.; Howard, Andrew W. +25 more
We report on the discovery of a transiting Earth-sized (0.95R⊕) planet around an M3.5 dwarf star at 57 pc, EPIC 249631677. The planet has a period of ∼3.14 days, i.e., ∼π, with an installation of 7.45 S⊕. The detection was made using publicly available data from K2's Campaign 15. We observed three additional transits with SPE…
Atmospheric Characterization and Further Orbital Modeling of κ Andromeda b
Currie, Thayne; De Rosa, Robert J.; Kwon, Jungmi +19 more
We present κ Andromeda b’s photometry and astrometry taken with Subaru/SCExAO+HiCIAO and Keck/NIRC2, combined with recently published SCExAO/CHARIS low-resolution spectroscopy and published thermal infrared photometry to further constrain the companion’s atmospheric properties and orbit. The Y/Y-K colors of κ And b are redder than field dwarfs, co…
Lithium in T Coronae Borealis
Strassmeier, K. G.; Munari, U.; Evans, A. +5 more
T Coronae Borealis is a recurrent, symbiotic nova system currently in quiescence between its periodic ≈80 yr cycle of eruptions. Observations during inter-outburst epochs provide an opportunity to study properties of the accretion disk and the M red giant. Here we present new irradiated (blackbody veiling) models, incorporating modern molecular op…
High-resolution Optical Spectroscopic Observations of Comet 21P/Giacobini-Zinner in Its 2018 Apparition
Shinnaka, Yoshiharu; Kawakita, Hideyo; Tajitsu, Akito
Comet 21P/Giacobini-Zinner is a peculiar comet from the viewpoints of the chemical and physical properties of its dust grains. We conduct optical high-resolution spectroscopic observations of the comet. The intensity ratios of forbidden oxygen lines (at 557.7, 630.0, and 636.4 nm) and ortho-to-para abundance ratios (OPRs) of water cations (H2…
Broadband Linear Polarization in the Region of the Open Star Cluster NGC 1817
Pandey, Jeewan C.; Singh, Sadhana
Multiband linear polarimetric observations of 125 stars in the region of the cluster NGC 1817 have been carried out intending to study properties of interstellar dust and grains in that direction. The polarization is found to be wavelength-dependent, being maximum in the V band with an average value of 0.95%. The foreground interstellar dust grain…
Dynamical Mass Estimates of the β Pictoris Planetary System through Gaussian Process Stellar Activity Modeling
Vandal, Thomas; Doyon, René; Rameau, Julien
Nearly 15 yr of radial velocity (RV) monitoring and direct imaging enabled the detection of two giant planets orbiting the young, nearby star β Pictoris. The δ Scuti pulsations of the star, which overwhelm planetary signals, need to be carefully suppressed. In this work, we independently revisit the analysis of the RV data following a different ap…