Search Publications
An Investigation of the Pleiades Cluster Using Machine Learning
Gao, Xin-hua
This paper presents an investigation on fundamental astrophysical properties of the Pleiades cluster (M 45) using high-precision astrometric and photometric data from the Gaia Data Release 2 (Gaia-DR2). To obtain reliable cluster members, a machine-learning (ML) method is used to compute membership probabilities for 31462 sample stars within a rad…
First Radial Velocity Results From the MINiature Exoplanet Radial Velocity Array (MINERVA)
Swift, Jonathan J.; Berlind, Perry; Calkins, Michael L. +52 more
The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA’s unique combination of high precision and high cadence over long tim…
An Optical and X-Ray Study of the Contact Binary, BH Cassiopeia
Zheng, Jie; Zhang, Yu; Esamdin, Ali +10 more
We present the revised and high-quality CCD time series observations in 2017 and 2018 of the W UMa-type contact binary BH Cas. The combination of our new determinations of minimum times and those collected from the literatures reveal a long-term period increase with a rate of dP/dt = +3.27 × 10-7 day yr-1, which can be accoun…
Gamma-Ray Polarimetry: A New Window for the Nonthermal Universe
Ilie, Cosmin
Over the past few decades, impressive progress has been made in the field of photon polarimetry, especially in the hard X-ray and soft gamma-ray energy regime. Measurements of the linear degree of polarization for some of the most energetic astrophysical sources, such as gamma-ray bursts (GRBs) or blazars, are now possible, at energies below the p…
Ultraviolet Activity as Indicators of Small-scale Magnetic Fields in γ Cassiopeiae
Smith, Myron A.
The recorded activity of γ Cas (B0.5 IVe) in the ultraviolet is important to an understanding of the mechanism behind this prototypical Be star’s high-energy activity, especially its hard X-ray emissions. The analysis here focuses first on the phasing of ultraviolet and optical light curves from different epochs. The rotational interpretation of t…
A GALEX Far-ultraviolet Study of Dwarf Stars in Moving Groups
Smith, Graeme H.; Cochrane, Kevin M.
Far-ultraviolet (FUV) GALEX photometry of main-sequence stars in moving groups is used to verify that there is a relationship between age and FUV broadband magnitude among such stars. Samples of dwarf stars were compiled for twelve moving groups and a search made for both GALEX FUV magnitudes on the AB system and Johnson BV photometry. These data …
Multivariate Time-series Analysis of Variable Objects in the Gaia Mission
Bouchy, Francois; Holl, Berry; Rimoldini, Lorenzo +5 more
In astronomy, we are witnessing an enormous increase in the number of source detections, precision, and diversity of measurements. Additionally, multi-epoch data is becoming the norm, making time-series analyses an important aspect of current astronomy. The Gaia mission is an outstanding example of a multi-epoch survey that provides measurements i…
Variables in the Southern Polar Region Evryscope 2016 Data Set
Trifonov, Trifon; Law, Nicholas M.; Fors, Octavi +6 more
The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (≈5% or greater) variable objects among 160,000 bright stars (mv < 14.5) near the South Celestial Pole. We developed a machine-learning-b…
Imaging and Analysis of Neon Nova V382 Vel Shell
Takeda, Larissa; Diaz, Marcos
We present the detection and imaging of the spatially resolved shell of nova V382 Vel with SOAR adaptive optics module (SAM). The shell was observed in narrow-band filters Hα and [O III] 5007 Å revealing different structures in each filter. The shell’s angular diameter obtained was 9.9 arcsec, equivalent to 2.8 × 1017 cm, using the dist…
A Six-year Image-subtraction Light Curve of SN2010jl
Sollerman, J.; Gal-Yam, A.; Kulkarni, S. R. +9 more
SN 2010jl was a luminous Type IIn supernova (SN), detected in radio, optical, X-ray and hard X-rays. Here we report on its six-year R- and g-band light curves obtained using the Palomar Transient Factory. The light curve was generated using a pipeline based on the proper image-subtraction method and we discuss the algorithm performances. As noted …