Search Publications
Photometric and Spectroscopic Studies of Superoutbursts of Three Dwarf Novae Independently Identified by the SVOM/GWAC System in 2018
Zheng, W.; Filippenko, A. V.; Xu, Y. +27 more
We report our photometric and spectroscopic follow-up observations of the superoutbursts of three dwarf novae (DNe; GWAC 180415A, GWAC 181017A, and GWAC 181211A) identified independently by the Ground Wide-angle Cameras system, one of the ground-based instruments of the China-France SVOM mission. Based on a combination of our photometry and that t…
Identifying Multiple Populations in M71 Using CN
Vesperini, Enrico; Gerber, Jeffrey M.; Friel, Eileen D.
We have observed the CN features at ∼3800 and 4120 Å as well as the CH band at ∼4300 Å for 145 evolved stars in the Galactic globular cluster M71 using the multi-object spectrograph, Hydra, on the Wisconsin-Indiana-Yale-NOAO-3.5 m telescope. We use these measurements to create two δCN indices finding that both distributions are best fit by two pop…
Study of Star Clusters in the M83 Galaxy with a Convolutional Neural Network
Bialopetravičius, Jonas; Narbutis, Donatas
We present a study of evolutionary and structural parameters of star cluster candidates in the spiral galaxy M83. For this we use a convolutional neural network trained on mock clusters and capable of fast identification and localization of star clusters, as well as inference of their parameters from multiband images. We use this pipeline to detec…
Optical Linear Polarization toward the Open Star Cluster Casado Alessi 1
Yadav, R. K. S.; Medhi, Biman J.; Pandey, Jeewan C. +1 more
We present B-, V-, R-, and I-band linear polarimetric observations of 73 stars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi 1). We aim to use polarimetry as a tool to investigate the properties and distribution of dust grains toward the direction of the cluster. The polarimetric observations were carried out using the AR…
Spectroscopic Studies of 30 Short-period Cataclysmic Variable Stars and Remarks on the Evolution and Population of Similar Objects
Thorstensen, John R.
We present spectroscopy and orbital periods Porb for 30 apparently nonmagnetic cataclysmic binaries with periods below ∼3 hr, nearly all of which are dwarf novae, mostly of the SU Ursae Majoris subclass. We then turn to the evidence supporting the prediction that short-period dwarf novae evolve toward longer periods after passing throug…
A Random Forest Approach to Identifying Young Stellar Object Candidates in the Lupus Star-forming Region
Melton, Elizabeth
The identification and characterization of stellar members within a star-forming region are critical to many aspects of star formation, including formalization of the initial mass function, circumstellar disk evolution, and star formation history. Previous surveys of the Lupus star-forming region have identified members through infrared excess and…
Probing UV-sensitive Pathways for CN and HCN Formation in Protoplanetary Disks with the Hubble Space Telescope
France, Kevin; Hoadley, Keri; Manara, Carlo F. +6 more
The UV radiation field is a critical regulator of gas-phase chemistry in surface layers of disks around young stars. In an effort to understand the relationship between photocatalyzing UV radiation fields and gas emission observed at infrared and submillimeter wavelengths, we present an analysis of new and archival Hubble Space Telescope (HST), Sp…
Mathematical Underpinnings of the Multiwavelength Structure of the Tip of the Red Giant Branch
Madore, Barry F.; Freedman, Wendy L.
We consider the application of the tip of the red giant branch (TRGB) in the optical and in the near-infrared for the determination of distances to nearby galaxies. We analyze ACS VI (F555W and F814W) data and self-consistently cross-calibrate WFC3-IR JH (F110W and F120W) data using an absolute magnitude calibration of MI = -4.05 mag as…
New Candidates for Planetary-mass Brown Dwarfs in IC 348
Luhman, K. L.; Hapich, C. J.
We have used infrared images obtained with the Wide Field Camera 3 on board the Hubble Space Telescope to search for planetary-mass brown dwarfs in the star-forming cluster IC 348. In those images, we have identified 12 objects that have colors indicative of spectral types later than M8, corresponding to masses of ≲30 MJup at the age of…
Proper-motion Membership Tests for Four Planetary Nebulae in Galactic Globular Clusters
Bond, Howard E.; Sahu, Kailash C.; Bellini, Andrea
Four planetary nebulae (PNe) are considered to be probable or possible members of Galactic globular clusters (GCs). These are Ps 1 = K648 in M15, GJJC 1 = IRAS 18333-2357 in M22, JaFu 1 in Palomar 6, and JaFu 2 in NGC 6441. In addition to lying close to the host GCs on the sky, these PNe have radial velocities that are consistent, within the error…