Search Publications
A New Dark Vortex on Neptune
de Pater, Imke; Wong, Michael H.; Baranec, Christoph +12 more
An outburst of cloud activity on Neptune in 2015 led to speculation about whether the clouds were convective in nature, a wave phenomenon, or bright companions to an unseen dark vortex (similar to the Great Dark Spot studied in detail by Voyager 2). The Hubble Space Telescope (HST) finally answered this question by discovering a new dark vortex at…
A Tale of “Two” Comets: The Primary Volatile Composition of Comet 2P/Encke Across Apparitions and Implications for Cometary Science
Vervack, Ronald J., Jr.; Kawakita, Hideyo; DiSanti, Michael A. +5 more
The highly favorable 2017 apparition of 2P/Encke allowed the first comprehensive comparison of primary volatile abundances in a given comet across multiple apparitions. This apparition offered opportunities to address pressing questions in cometary science, including investigating evolutionary and/or heliocentric distance (R h) effects …
Improving Gaia Parallax Precision with a Data-driven Model of Stars
Bovy, Jo; Leistedt, Boris; Hogg, David W. +2 more
Converting a noisy parallax measurement into a posterior belief over distance requires inference with a prior. Usually, this prior represents beliefs about the stellar density distribution of the Milky Way. However, multiband photometry exists for a large fraction of the Gaia-TGAS Catalog and is incredibly informative about stellar distances. Here…
The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1 m Telescope
Kulkarni, S. R.; Baranec, Christoph; Duev, Dmitry A. +5 more
Robo-AO is an autonomous laser guide star adaptive optics (AO) system recently commissioned at the Kitt Peak 2.1 m telescope. With the ability to observe every clear night, Robo-AO at the 2.1 m telescope is the first dedicated AO observatory. This paper presents the imaging performance of the AO system in its first 18 months of operations. For a m…
Transformation of HST WFC3/UVIS Filters to the Standard BVI System
Harris, William E.
Empirical transformations of selected broadband filters in the Hubble Space Telescope Wide Field Camera 3 (WFC3)/UVIS camera into the BVI system are derived. These conversions employ photometry of stars in a standard field in the globular cluster 47 Tucanae that has repeatedly been imaged with both the WFC3 and Advanced Camera for Surveys (ACS) ca…
Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B
Schneider, Glenn; Metchev, Stanimir; Apai, Dániel +11 more
Time-resolved observations of brown dwarfs’ rotational modulations provide powerful insights into the properties of condensate clouds in ultra-cool atmospheres. Multi-wavelength light curves reveal cloud vertical structures, condensate particle sizes, and cloud morphology, which directly constrain condensate cloud and atmospheric circulation model…
Starspot Occultations in Infrared Transit Spectroscopy: The Case of WASP-52b
Deming, Drake; Stevenson, Kevin B.; López-Morales, Mercedes +7 more
Stellar activity is one of the main obstacles to high-precision exoplanet observations and has motivated extensive studies in detection and characterization problems. Most efforts focused on unocculted starspots in optical transit spectrophotometry, while the impact of starspot crossings is assumed to be negligible in the near-infrared. Here, we p…
High-time-resolution Photometry of AR Scorpii: Confirmation of the White Dwarf’s Spin-down
Garnavich, Peter; Littlefield, Colin; Myers, Gordon +3 more
The unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly coherent pulsation every 1.97 minutes. Over the course of two years, we obtained 39 hours of time-resolved, optical photometry of AR Sco at a typical cadence of 5 s to stu…
Improved Main-sequence Turnoff Ages of Young Open Clusters: Multicolor UBV Techniques and the Challenges of Rotation
Cummings, Jeffrey D.; Kalirai, Jason S.
Main-sequence turnoff ages in young open clusters are complicated by turnoffs that are sparse, have high binarity fractions, can be affected by differential reddening, and typically include a number of peculiar stars. Furthermore, stellar rotation can have a significant effect on a star’s photometry and evolutionary timescale. In this paper we ana…
The Rotational Evolution of Young, Binary M Dwarfs
Pinsonneault, Marc; Cody, Ann Marie; Hillenbrand, Lynne A. +5 more
We have analyzed K2 light curves for more than 3000 low-mass stars in the ∼8 Myr old Upper Sco association, the ∼125 Myr age Pleiades open cluster, and the ∼700 Myr old Hyades and Praesepe open clusters to determine stellar rotation rates. Many of these K2 targets show two distinct periods, and for the lowest-mass stars in these clusters, virtuall…