Search Publications
Resonant capture in quadruple stellar systems
Tremaine, Scott
Some quadruple star systems in the hierarchical 2 + 2 configuration exhibit orbit-orbit resonances between the two compact binaries. We show that the most important resonances occur at period ratios of 1:1, 3:2, and 2:1. We describe the conditions required for capture and show that they can be satisfied at the 3:2 and 2:1 resonances in binaries th…
Predictions of Gaia's prize microlensing events are flawed
McGill, Peter; Everall, Andrew; Boubert, Douglas +1 more
Precision astrometry from the second Gaia data release has allowed astronomers to predict 5787 microlensing events, with 528 of these having maximums within the extended Gaia mission (J2014.5-J2026.5). Future analysis of the Gaiatime-series astrometry of these events will, in some cases, lead to precise gravitational mass measurements of the lens.…
The small inner satellites of Saturn: Shapes, structures and some implications
Thomas, P.; Helfenstein, P.
Properties of the small inner satellites of Saturn are updated using final Cassini image data. The equatorial ridges on Pan and Atlas are morphologically, structurally, and gravitationally distinct from their cores and represent distinct additions to, rather than modifications of, the precursor bodies. Exposures of lineated substrates on Pandora a…
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. VI. Wide, Energetic Outflows in SDSS J0755+2306
Xu, Xinfeng; Kriss, Gerard A.; Arav, Nahum +2 more
We present the analysis of two outflows (S1 at -5500 km s-1 and S2 at -9700 km s-1) seen in recent Hubble Space Telescope/Cosmic Origins Spectrograph observations of quasar SDSS J0755+2306 (z = 0.854). The outflows are detected as absorption troughs from both high-ionization species, including N III, O III, and S IV, and very…
Properties of Streamer Wave Events Observed during the STEREO Era
Van Doorsselaere, Tom; Zhukov, Andrei N.; Decraemer, Bieke
Transverse waves are sometimes observed in solar helmet streamers, typically after the passage of a coronal mass ejection (CME). The CME-driven shock wave moves the streamer sideways, and a decaying oscillation of the streamer is observed after the CME passage. Previous works generally reported observations of streamer oscillations taken from a si…
Periodic Eruptive Variability of the Isolated Pre-main-sequence Star V347 Aurigae
Hillenbrand, L. A.; Dahm, S. E.
V347 Aurigae is associated with the small dark cloud L1438 and appears to be an isolated pre-main-sequence star located at distance d ≈ 200 pc. Multi-epoch, archival photometry reveals periodic brightness variations with amplitude V ≈ 2.0 mag occurring on timescales of ∼160 days that have persisted for decades. Regular-cadence, optical imaging of …
Planetary nebulae with Wolf-Rayet-type central stars - I. The case of the high-excitation NGC 2371
Guerrero, M. A.; Toalá, J. A.; Todt, H. +4 more
We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf-Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morp…
Planetary candidates transiting cool dwarf stars from campaigns 12 to 15 of K2
Bonavera, L.; Schlieder, Joshua E.; Howell, Steve B. +15 more
We analysed the photometry of 20 038 cool stars from campaigns 12, 13, 14, and 15 of the K2 mission in order to detect, characterize, and validate new planetary candidates transiting low-mass stars. We present a catalogue of 25 new periodic transit-like signals in 22 stars, of which we computed the parameters of the stellar host for 19 stars and t…
Kinematic study of the association Cyg OB3 with Gaia DR2
Boubert, Douglas; Gandhi, Poshak; Rao, Anjali +3 more
We study the stellar kinematic properties and spatial distribution of the association Cyg OB3 using precise astrometric data from Gaia DR2. All known O- and B-type stars in Cyg OB3 region with positions, parallaxes, and proper motions available are included, comprising a total of 41 stars. The majority of stars are found to be concentrated at a he…
Fifth force induced by a chameleon field on nested cylinders
Bergé, Joel; Pernot-Borràs, Martin; Uzan, Jean-Philippe +1 more
This article investigates the properties of a scalar fifth force that arises in a scalar tensor-theory with a chameleon screening mechanism in the context of gravity space missions like the MICROSCOPE experiment. In such an experiment, the propagation of the chameleon field inside the nested cylinders of the experiment causes a fifth force when th…