929 research outputs found
Benchmarking Individual Tree Mapping with Sub-meter Imagery
There is a rising interest in mapping trees using satellite or aerial
imagery, but there is no standardized evaluation protocol for comparing and
enhancing methods. In dense canopy areas, the high variability of tree sizes
and their spatial proximity makes it arduous to define the quality of the
predictions. Concurrently, object-centric approaches such as bounding box
detection usuallyperform poorly on small and dense objects. It thus remains
unclear what is the ideal framework for individual tree mapping, in regards to
detection and segmentation approaches, convolutional neural networks and
transformers. In this paper, we introduce an evaluation framework suited for
individual tree mapping in any physical environment, with annotation costs and
applicative goals in mind. We review and compare different approaches and deep
architectures, and introduce a new method that we experimentally prove to be a
good compromise between segmentation and detection
A Direct Imaging Survey of Spitzer detected debris disks: Occurrence of giant planets in dusty systems
We describe a joint high contrast imaging survey for planets at Keck and VLT
of the last large sample of debris disks identified by the Spitzer Space
Telescope. No new substellar companions were discovered in our survey of 30
Spitzer-selected targets. We combine our observations with data from four
published surveys to place constraints on the frequency of planets around 130
debris disk single stars, the largest sample to date. For a control sample, we
assembled contrast curves from several published surveys targeting 277 stars
which do not show infrared excesses. We assumed a double power law distribution
in mass and semi-major axis of the form f(m,a) = , where
we adopted power law values and logarithmically flat values for the mass and
semi-major axis of planets. We find that the frequency of giant planets with
masses 5-20 and separations 10-1000 AU around stars with debris
disks is 6.27% (68% confidence interval 3.68 - 9.76%), compared to 0.73% (68%
confidence interval 0.20 - 1.80%) for the control sample of stars without
disks. These distributions differ at the 88% confidence level, tentatively
suggesting distinctness of these samples.Comment: Accepted to A
The Demographics and Atmospheres of Giant Planets with the ELTs
Gas giants are the most readily detectable exoplanets but fundamental
questions about their system architectures, formation, migration, and
atmospheres have been unanswerable with the current generation of ground- and
space-based facilities. The dominant techniques to detect and characterize
giant planets radial velocities, transits, direct imaging, microlensing,
and astrometry are each isolated to a limited range of planet masses,
separations, ages, and temperatures. These windows into the arrangement and
physical properties of giant planets have spawned new questions about the
timescale and location of their assembly; the distributions of planet mass and
orbital separation at young and old ages; the composition and structure of
their atmospheres; and their orbital and rotational angular momentum
architectures. The ELTs will address these questions by building bridges
between these islands of mass, orbital distance, and age. The angular
resolution, collecting area, all-sky coverage, and novel instrumentation suite
of these facilities are needed to provide a complete map of the orbits and
atmospheric evolution of gas giant planets (0.310 ) across
space (0.1100 AU) and time (1 Myr to 10 Gyr). This white paper highlights
the scientific potential of the GMT and TMT to address these outstanding
questions, with a particular focus on the role of direct imaging and
spectroscopy of large samples of giant planets that will soon be made available
with .Comment: White paper for the Astro2020 decadal surve
The McDonald Accelerating Stars Survey (MASS): White Dwarf Companions Accelerating the Sun-like Stars 12 Psc and HD 159062
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 yr ), which together with relative
astrometry from Keck/NIRC2 and the astrometric acceleration between
and DR2 yields a dynamical mass of = 0.605
for 12 Psc B, a semi-major axis of 40 AU, and an
eccentricity of 0.840.08. We also report an updated orbit 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 = 0.609
for HD 159062 B, a semi-major axis of 60 AU, and
preference for circular orbits (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.Comment: Accepted to A
The McDonald Accelerating Stars Survey (MASS): White Dwarf Companions Accelerating the Sun-like Stars 12 Psc and HD 159062
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 = 0.605^(+0.021)_(−0.022) M ⊙ for 12 Psc B, a semimajor axis of 40⁺²₋₄ 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 = 0.609^(+0.010)_(−0.011) M⊙ for HD 159062 B, a semimajor axis of 60⁺⁵₋₇ 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
The Planetary Systems Imager: 2-5 Micron Channel
We summarize the red channel (2-5 micron) of the Planetary Systems Imager
(PSI), a proposed second-generation instrument for the TMT. Cold exoplanets
emit the majority of their light in the thermal infrared, which means these
exoplanets can be detected at a more modest contrast than at other wavelengths.
PSI-Red will be able to detect and characterize a wide variety of exoplanets,
including radial-velocity planets on wide orbits, accreting protoplanets in
nearby star-forming regions, and reflected-light planets around the nearest
stars. PSI-Red will feature an imager, a low-resolution lenslet integral field
spectrograph, a medium-resolution lenslet+slicer integral field spectrograph,
and a fiber-fed high-resolution spectrograph.Comment: 7 pages, 5 figure
Update on the Preliminary Design of SCALES: the Santa Cruz Array of Lenslets for Exoplanet Spectroscopy
SCALES (Santa Cruz Array of Lenslets for Exoplanet Spectroscopy) is a 2-5
micron high-contrast lenslet integral-field spectrograph (IFS) driven by
exoplanet characterization science requirements and will operate at W. M. Keck
Observatory. Its fully cryogenic optical train uses a custom silicon lenslet
array, selectable coronagraphs, and dispersive prisms to carry out integral
field spectroscopy over a 2.2 arcsec field of view at Keck with low ()
spectral resolution. A small, dedicated section of the lenslet array feeds an
image slicer module that allows for medium spectral resolution (),
which has not been available at the diffraction limit with a coronagraphic
instrument before. Unlike previous IFS exoplanet instruments, SCALES is capable
of characterizing cold exoplanet and brown dwarf atmospheres ( K) at
bandpasses where these bodies emit most of their radiation while capturing
relevant molecular spectral features.Comment: 24 pages, 13 figures, SPIE Astronomical Instruments and Telescopes
2020 conferenc
Recovering simulated planet and disk signals using SCALES aperture masking
The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy
(SCALES) instrument is a lenslet-based integral field spectrograph that will
operate at 2 to 5 microns, imaging and characterizing colder (and thus older)
planets than current high-contrast instruments. Its spatial resolution for
distant science targets and/or close-in disks and companions could be improved
via interferometric techniques such as sparse aperture masking. We introduce a
nascent Python package, NRM-artist, that we use to design several SCALES masks
to be non-redundant and to have uniform coverage in Fourier space. We generate
high-fidelity mock SCALES data using the scalessim package for SCALES' low
spectral resolution modes across its 2 to 5 micron bandpass. We include
realistic noise from astrophysical and instrument sources, including Keck
adaptive optics and Poisson noise. We inject planet and disk signals into the
mock datasets and subsequently recover them to test the performance of SCALES
sparse aperture masking and to determine the sensitivity of various mask
designs to different science signals
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