A5072019035- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Planetary Science and Exploration
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Geomagnetism and Paleomagnetism Studies
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Space Satellite Systems and Control
- Astronomical and nuclear sciences
- Astrophysical Phenomena and Observations
- Isotope Analysis in Ecology
- Calibration and Measurement Techniques
- Molecular Spectroscopy and Structure
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Marine and environmental studies
- CCD and CMOS Imaging Sensors
- earthquake and tectonic studies
- Distributed systems and fault tolerance
- Quantum chaos and dynamical systems
- Photocathodes and Microchannel Plates
- Scientific Research and Discoveries
Pennsylvania State University
2016-2023
NASA Exoplanet Science Institute
2020
University of California, Berkeley
2014-2016
Center for Astrophysics Harvard & Smithsonian
2010-2014
Hearst (United States)
2014
CFA Institute
2013
Harvard University
2011
Abstract We present a statistical analysis of the first 300 stars observed by Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections our contrast curves we infer underlying distributions substellar companions with respect to their mass, semimajor axis, host stellar mass. uncover strong correlation between planet occurrence rate star M * > 1.5 ⊙ more likely masses 2 13 Jup axes 3–100 au at 99.92% confidence. fit...
An exoplanet extracted from the bright Direct imaging of Jupiter-like exoplanets around young stars provides a glimpse into how our solar system formed. The brightness requires use next-generation devices such as Gemini Planet Imager (GPI). Using GPI, Macintosh et al. discovered planet orbiting star, 51 Eridani (see Perspective by Mawet). planet, Eri b, has methane signature and is probably smallest that been directly imaged. These findings open door to understanding origins herald dawn new...
Radial velocity measurements of stellar reflex motion have revealed many extrasolar planets, but gaps in the observations produce aliases, spurious frequencies that are frequently confused with planets' orbital frequencies. In case Gl 581 d, distinction between an alias and true frequency was a frozen, dead planet possibly hospitable to life (Udry et al. 2007; Mayor 2009). To improve characterization planetary systems, we describe how aliases originate present new approach for distinguishing...
The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of art Doppler precision and identified critical path challenges for reaching 10 cm s−1 measurement precision. presentations discussion key issues instrumentation data analysis workshop recommendations achieving this bold are summarized here. Beginning with High Accuracy Velocity Planet Searcher spectrograph, technological advances radial velocity (RV) measurements have focused building extremely stable...
Abstract The rotation of a star and the revolutions its planets are not necessarily aligned. This article reviews measurement techniques, key findings, theoretical interpretations related to obliquities (spin–orbit angles) planet-hosting stars. best measurements for stars with short-period giant planets, which have been found on prograde, polar, retrograde orbits. It seems likely that dynamical processes such as planet–planet scattering secular perturbations responsible tilting orbits...
We have detected transits of the innermost planet "e" orbiting 55 Cnc (V=6.0), based on two weeks nearly continuous photometric monitoring with MOST space telescope. The occur period (0.74 d) and phase that had been predicted by Dawson & Fabrycky, expected duration depth for crossing a Sun-like star hot super-Earth. Assuming star's mass radius to be 0.963_{-0.029}^{+0.051} M_sun 0.943 +/- 0.010 R_sun, planet's mass, radius, mean density are 8.63 0.35 Mearth, 2.00 0.14 Rearth,...
Gas giants orbiting interior to the ice line are thought have been displaced from their formation locations by processes that remain debated. Here we uncover several new metallicity trends, which together may indicate two competing mechanisms deliver close-in giant planets: gentle disk migration, operating in environments with a range of metallicities, and violent planet-planet gravitational interactions, primarily triggered metal-rich systems multiple planets can form. First, show 99.1%...
Hot Jupiters were the first exoplanets to be discovered around main sequence stars and astonished us with their close-in orbits. They are a prime example of how have challenged our textbook, solar-system inspired story planetary systems form evolve. More than twenty years after discovery hot Jupiter, there is no consensus on predominant origin channel. Three classes Jupiter creation hypotheses been proposed: in situ formation, disk migration, high eccentricity tidal migration. Although...
Exoplanet orbital eccentricities offer valuable clues about the history of planetary systems. Eccentric, Jupiter-sized planets are particularly interesting: they may link "cold" Jupiters beyond ice line to close-in hot Jupiters, which unlikely have formed in situ. To date, individual transiting primarily come from radial-velocity measurements. Kepler has discovered hundreds spanning a range periods, but faintness host stars precludes follow-up most. Here, we demonstrate Bayesian method...
Abstract The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program in 2013–2017 with the Canada–France–Hawaii Telescope, surveyed 155 deg 2 of sky to depths m r = 24.1–25.2. We present 838 outer solar system discoveries that are entirely free ephemeris bias. This increases inventory trans-Neptunian objects (TNOs) accurately known orbits by nearly 50%. Each minor planet has 20–60 Gaia /Pan-STARRS-calibrated astrometric measurements made over 2–5 oppositions, which allows...
The giant impact phase of terrestrial planet formation establishes connections between super-Earths' orbital properties (semimajor axis spacings, eccentricities, mutual inclinations) and interior compositions (the presence or absence gaseous envelopes). Using N-body simulations analytic arguments, we show that spacings derive not only from but also inclinations. Flatter systems attain tighter a consequence an eccentricity equilibrium gravitational scatterings, which increase mergers, damp...
It is debated whether the two hot Jupiter populations --- those on orbits misaligned from their host star's spin axis and well-aligned result migration channels or tidal realignment regimes. Here I demonstrate that equilibrium tides raised by a planet its star can account for three observed spin-orbit alignment trends: aligned of Jupiters orbiting cool stars, planetary mass cut-off retrograde planets, stratification stars' rotation frequencies. The first trend be caused strong versus weak...
Neptune's dynamical history shaped the current orbits of Kuiper belt objects (KBOs), leaving clues to planet's orbital evolution. In "classical" region, a population dynamically "hot" high-inclination KBOs overlies flat "cold" with distinct physical properties. Simulations qualitatively different histories for Neptune -including smooth migration on circular orbit or scattering by other planets high eccentricity - have not simultaneously produced both populations. We explore general assembly...
We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, precision measurements. While Pic b's near-IR colors mimic those a standard, cloudy early-to-mid L dwarf, it is overluminous mid-infrared compared field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And 1RXJ 1609B—match JHKsL' photometry its...
Planets with sizes between those of Earth and Neptune divide into two populations: purely rocky bodies whose atmospheres contribute negligibly to their sizes, larger gas-enveloped planets possessing voluminous optically thick atmospheres. We show that whether a planet forms or depends on the solid surface density its parent disk. Assembly times for cores are sensitive disk density. Lower densities spawn smaller planetary embryos; assemble core given mass, embryos require more mergers farther...
Observing the Rossiter-McLaughlin effect during a planetary transit allows determination of angle $\lambda$ between sky projections star's spin axis and planet's orbital axis. Such observations have revealed large population well-aligned systems smaller misaligned systems, with values ranging up to 180$^\circ$. For subset 57 we can now go beyond projection determine 3-d obliquity $\psi$ by combining data constraints on line-of-sight inclination Here show that do not span full range...
We present the discovery and characterization of a giant planet orbiting young Sun-like star Kepler-63 (KOI-63, mKp = 11.6, Teff 5576 K, M⋆ 0.98 M☉). The transits every 9.43 days, with apparent depth variations brightening anomalies caused by large starspots. planet's radius is 6.1 ± 0.2 R⊕, based on transit light curve estimated stellar parameters. mass could not be measured existing radial-velocity data, due to high level activity, but if we assume circular orbit, then can place rough...
The orbits of giant extrasolar planets often have surprisingly small semi-major axes, large eccentricities, or severe misalignments between their normals and host stars' spin axes. In some formation scenarios invoking Kozai-Lidov oscillations, an external planetary companion drives a planet onto orbit having these properties. mutual inclinations for oscillations can be not been confirmed observationally. Here we deduce that observed eccentric warm Jupiters with companions oscillate 35-65...
We determine the orbital eccentricities of individual small Kepler planets, through a combination asteroseismology and transit light-curve analysis. are able to constrain 51 systems with single transiting planet, which supplement our previous measurements 66 planets in multi-planet systems. Through Bayesian hierarchical analysis, we find evidence that only one detected planet have different eccentricity distribution than multiple planets. The single-transiting is well described by positive...
We present the discovery of a brown dwarf companion to debris disk host star HR 2562. This object, discovered with Gemini Planet Imager (GPI), has projected separation 20.3$\pm$0.3 au (0.618$\pm$0.004") from star. With high astrometric precision afforded by GPI, we have confirmed common proper motion 2562B only month time baseline between observations more than $5\sigma$. Spectral data in $J$, $H$, and $K$ bands show morphological similarity L/T transition objects. assign spectral type...
We present H-band observations of β Pic with the Gemini Planet Imager's (GPI's) polarimetry mode that reveal debris disk between ∼03 (6 AU) and ∼17 (33 AU), while simultaneously detecting b. The polarized image was fit a dust density model combined Henyey–Greenstein scattering phase function. best-fit indicates inclined to line sight () position angle (PA) (slightly offset from main outer disk, ), extends an inner radius well outside GPI's field view. In addition, we updated orbit for b...
The HR 8799 system uniquely harbors four young super-Jupiters whose orbits can provide insights into the system's dynamical history and constrain masses of planets themselves. Using Gemini Planet Imager (GPI), we obtained down to one milliarcsecond precision on astrometry these planets. We assessed four-planet orbit models with different levels constraints found that assuming are near 1:2:4:8 period commensurabilities, or coplanar, does not worsen fit. added prior must have been stable for...
Significance The Sun’s equator lines up with the orbits of planets. This fact supports theory that stars and their planets inherit angular momentum from same source: gravitational collapse a molecular cloud. Most astronomers expected spin-orbit alignment to be universal feature planetary systems. proved false: many drastic misalignments are known, possible reasons have been offered. In one theory, distant companion star upsets at an early stage, while is still surrounded by protoplanetary...
The vertical warp in the debris disk β Pictoris—an inclined inner extending into a flat outer disk—has long been interpreted as signpost of planet on an orbit. Direct images spanning 2004–2010 have revealed Pictoris b, with mass and orbital distance consistent this picture. However, it was recently reported that orbit b is aligned disk, not thus lacks inclination to disk. We explore three scenarios for reconciling apparent misalignment directly imaged warped Pictoris: observational...