Abstract
We present Keck/NIRC2
K
p
L
p
high-contrast imaging observations of a J0337 protoplanetary disk. The data discover the spatially-resolved large cavity, which is the second report among ...protoplanetary disks in the Perseus star-forming region after the LkH
α
330 system. Our data and forward modeling using RADMC-3D suggests ∼80 au for the cavity radius. There is discrepancy between J0337's spectral energy distribution (SED) and the modeled SED at ∼10
μ
m and this suggests an unseen inner disk. We also searched for companions around J0337 but did not detect any companion candidates at separations between 0.″1 and 2.″5. The
L
p
-band detection limit corresponds to ∼20
M
Jup
at 60 au, ∼9–10
M
Jup
at 90 au, and ∼3
M
Jup
at >120 au. Compared with other young systems with large cavities such as PDS 70 and RX J1604, multiple Jovian planets, a single eccentric Jovian planet, or a massive brown dwarf at an inner separation could exist within the cavity.
We explore opportunities afforded by an extremely large telescope design comprised of ill-figured randomly varying subapertures. The veracity of this approach is demonstrated with a laboratory scaled ...system whereby we reconstruct a white light binary point source separated by 2.5 times the diffraction limit. With an inherently unknown varying random point spread function, the measured speckle images require a restoration framework that combine support vector machine based lucky imaging and non-negative matrix factorization based multiframe blind deconvolution. To further validate the approach, we model the experimental system to explore sub-diffraction-limited performance, and an object comprised of multiple point sources.
High-contrast imaging is the primary path to the direct detection and characterization of Earth-like planets around solar-type stars; a cleverly designed internal coronagraph suppresses the light ...from the star, revealing the elusive circumstellar companions. However, future large-aperture telescopes (>4 m in diameter) will likely have segmented primary mirrors, which cause additional diffraction of unwanted stellar light. Here we present the first high-contrast laboratory demonstration of an apodized vortex coronagraph, in which an apodizer is placed upstream of a vortex focal plane mask to improve its performance with a segmented aperture. The gray-scale apodization is numerically optimized to yield a better sensitivity to faint companions assuming an aperture shape similar to the LUVOIR-B concept. Using wavefront sensing and control over a one-sided dark hole, we achieve a raw contrast of 2 × 10−8 in monochromatic light at 775 nm, and a raw contrast of 4 × 10−8 in a 10% bandwidth. These results open the path to a new family of coronagraph designs, optimally suited for next-generation segmented space telescopes.
Abstract
The detection of satellites around extrasolar planets, so called exomoons, remains a largely unexplored territory. In this work, we study the potential of detecting these elusive objects ...from radial velocity monitoring of self-luminous, directly imaged planets. This technique is now possible thanks to the development of dedicated instruments combining the power of high-resolution spectroscopy and high-contrast imaging. First, we demonstrate a sensitivity to satellites with a mass ratio of 1%–4% at separations similar to the Galilean moons from observations of a brown-dwarf companion (HR 7672 B;
K
mag
= 13; 0.″7 separation) with the Keck Planet Imager and Characterizer (
R
∼ 35,000 in the
K
band) at the W. M. Keck Observatory. Current instrumentation is therefore already sensitive to large unresolved satellites that could be forming from gravitational instability akin to binary star formation. Using end-to-end simulations, we then estimate that future instruments such as the Multi-Object Diffraction-limited High-resolution Infrared Spectrograph, planned for the Thirty Meter Telescope, should be sensitive to satellites with mass ratios of ∼10
−4
. Such small moons would likely form in a circumplanetary disk similar to the Jovian satellites in the solar system. Looking for the Rossiter–McLaughlin effect could also be an interesting pathway to detecting the smallest moons on short orbital periods. Future exomoon discoveries will allow precise mass measurements of the substellar companions that they orbit and provide key insight into the formation of exoplanets. They would also help constrain the population of habitable Earth-sized moons orbiting gas giants in the habitable zone of their stars.
Abstract
We present the discovery of a white dwarf companion to the G1 V star 12 Psc found as part of a Keck adaptive optics imaging survey of long-term accelerating stars from the McDonald ...Observatory Planet Search Program. Twenty years of precise radial-velocity monitoring of 12 Psc with the Tull Spectrograph at the Harlan J. Smith telescope reveals a moderate radial acceleration (≈10 m s
−1
yr
−1
), which together with relative astrometry from Keck/NIRC2 and the astrometric acceleration between Hipparcos and Gaia DR2 yields a dynamical mass of
M
B
=
M
⊙
for 12 Psc B, a semimajor axis of
au, and an eccentricity of 0.84 ± 0.08. We also report an updated orbital fit of the white dwarf companion to the metal-poor (but barium-rich) G9 V dwarf HD 159062 based on new radial-velocity observations from the High-Resolution Spectrograph at the Hobby–Eberly Telescope and astrometry from Keck/NIRC2. A joint fit of the available relative astrometry, radial velocities, and tangential astrometric acceleration yields a dynamical mass of
M
B
=
M
⊙
for HD 159062 B, a semimajor axis of
au, and preference for circular orbits (
e
< 0.42 at 95% confidence). 12 Psc B and HD 159062 B join a small list of resolved Sirius-like benchmark white dwarfs with precise dynamical mass measurements which serve as valuable tests of white dwarf mass–radius cooling models and probes of AGB wind accretion onto their main-sequence companions.
Abstract
The formation and evolution pathway for the directly imaged multiplanetary system HR 8799 remains mysterious. Accurate constraints on the chemical composition of the planetary atmosphere(s) ...are key to solving the mystery. We perform a detailed atmospheric retrieval on HR 8799 c to infer the chemical abundances and abundance ratios using a combination of photometric data along with low- and high-resolution spectroscopic data (
R
∼ 20–35,000). We specifically retrieve C/H, O/H, and C/O and find them to be
0.55
−
0.39
+
0.36
,
0.47
−
0.32
+
0.31
, and
0.67
−
0.15
+
0.12
at 68% confidence. The superstellar C and O abundances, yet a stellar C/O ratio, reveal a potential formation pathway for HR 8799 c. Planet c, and likely the other gas giant planets in the system, formed early on (likely within ∼1 Myr), followed by further atmospheric enrichment in C and O through the accretion of solids beyond the CO ice line. The enrichment either preceded or took place during the early phase of the inward migration to the current planet locations.
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