Abstract
The detection of emission lines associated with accretion processes is a direct method for studying how and where gas giant planets form, how young planets interact with their natal ...protoplanetary disk, and how volatile delivery to their atmosphere takes place. H
α
(
λ
= 0.656
μ
m) is expected to be the strongest accretion line observable from the ground with adaptive optics systems, and is therefore the target of specific high-contrast imaging campaigns. We present MagAO-X and Hubble Space Telescope (HST) data obtained to search for H
α
emission from the previously detected protoplanet candidate orbiting AS209, identified through Atacama Large Millimeter/submillimeter Array observations. No signal was detected at the location of the candidate, and we provide limits on its accretion. Our data would have detected an H
α
emission with
F
H
α
> 2.5 ± 0.3 × 10
−16
erg s
−1
cm
−2
, a factor 6.5 lower than the HST flux measured for PDS70 b. The flux limit indicates that if the protoplanet is currently accreting it is likely that local extinction from circumstellar and circumplanetary material strongly attenuates its emission at optical wavelengths. In addition, the data reveal the first image of the jet north of the star as expected from previous detections of forbidden lines. Finally, this work demonstrates that current ground-based observations with extreme adaptive optics systems can be more sensitive than space-based observations, paving the way to the hunt for small planets in reflected light with extremely large telescopes.
ABSTRACT
Objective: To investigate the effects of moxifloxacin on the cornea of normal human eyes using confocal microscopy and slit-lamp biomicroscopy.
Methods: This study enrolled adult volunteers ...who had a normal baseline ophthalmic examination. The dose regimen, similar to that of patients undergoing cataract extraction, was one drop of moxifloxacin in one eye four times a day for 3 days. The untreated fellow eye served as the control. Subjects had a baseline examination (Visit 1), started moxifloxacin the next day, and were examined 24 h (Visit 2) and 72 h (Visit 3) after starting medication. At each visit, visual acuity and adverse effects were recorded, slit-lamp examination with fluorescein was used to measure tear break-up time, and endothelial and epithelial cell counts were determined using confocal microscopy.
Results: Fifteen volunteers (mean age 37 ± 7 years) enrolled. No significant difference in visual acuity, tear break-up time, endothelial or epithelial cell counts was noted between the treated and fellow eye. Subjects experienced no significant decrease in visual acuity, tear break-up time, or endothelial cell counts during the 3‐day treatment period in either eye. Epithelial cell counts were stable at Visits 1 and 2, and decreased similarly in the treated and control eye at Visit 3.
Conclusions: Moxifloxacin was safe for use during the 3‐day treatment period. Moxifloxacin causes no significant epithelial or endothelial toxicity, and has no effect on visual acuity or ocular surface integrity in healthy subjects treated using a dosing regimen that simulated prophylactic use following cataract surgery.
ABSTRACT
We report the confirmation of HIP 67506 C, a new stellar companion to HIP 67506 A. We previously reported a candidate signal at 2λ/D (240 mas) in L′ in MagAO/Clio imaging using the binary ...differential imaging technique. Several additional indirect signals showed that the candidate signal merited follow-up: significant astrometric acceleration in Gaia DR3, Hipparcos–Gaia proper motion anomaly, and overluminosity compared to single main-sequence stars. We confirmed the companion, HIP 67506 C, at 0.1 arcsec with MagAO-X in 2022 April. We characterized HIP 67506 C MagAO-X photometry and astrometry, and estimated spectral-type K7-M2; we also re-evaluated HIP 67506 A in light of the close companion. Additionally, we show that a previously identified 9 arcsec companion, HIP 67506 B, is a much further distant unassociated background star. We also discuss the utility of indirect signposts in identifying small inner working angle candidate companions.
Known exoplanets are 10 thousand to 10 billion times fainter than their host stars. These high contrast ratios present significant challenges for the design of instruments to image exoplanets ...directly. Ground-based observatories face the additional challenge of atmospheric turbulence degrading the image quality. Astronomers have developed extreme adaptive optics (ExAO) instruments that are optimized for correcting atmospheric turbulence and suppressing starlight. Within the next decade, the world will see a new generation of telescopes with diameters up to 39 meters, called the Giant Segmented Mirror Telescopes (GSMT). The GSMTs have the angular resolution and light-collecting power to detect and characterize potentially habitable terrestrial exoplanets for the first time. This will only be achievable if the performance of GSMT-ExAO systems is optimized. Alternative architectures of wavefront sensors are under consideration for GSMT-ExAO instruments considering the trade-offs between detector size, speed, and noise that determine the performance of GSMT-ExAO wavefront control. This dissertation aims to develop the three-sided pyramid wavefront sensor(3PWFS) as an alternative GSMT-ExAO wavefront sensor. The 3PWFS uses fewer detector pixels so it is less sensitive to read noise than the 4PWFS. In this work, I develop a mathematical formalism based on the diffraction theory description of the Foucault knife-edge test that predicts the intensity pattern after the pyramid wavefront sensors (PWFS). I use these results to motivate methods for processing the signals from a 3PWFS and implement this methodology in an end-to-end adaptive optics simulation to compare the performance of the 3PWFS to the 4PWFS. I will describe the design and alignment of the Comprehensive Adaptive Optics and Coronagraph Test Instrument (CACTI), a new ExAO testbed designed with the flexibility to support visiting instruments and to be easily re-configurable to perform multiple experiments. Both a 3PWFS and 4PWFS were integrated into CACTI to demonstrate the operation of a 3PWFS and compare it to the 4PWFS.
Linking meteorites to source regions in the main asteroid belt is important for understanding the conditions under which their parent bodies formed. Ordinary chondrites are the most abundant class of ...meteorites on Earth, totaling 86% of all collected samples. Some S-type asteroids/families have been proposed as sources for the three different (H, L, and LL) types of ordinary chondrites with Hebe, Agnia, Merxia, and Koronis families being the source for H chondrites, Gefion for H/L chondrites, and Flora family for LL chondrites. However, the composition and meteorite affinity of several large S-type main belt asteroids remains unconstrained leaving the possibility of additional source regions for ordinary chondrite meteorites. Here we investigate the surface composition of three large S-type asteroids, (3) Juno, (7) Iris, and (25) Phocaea, using their near-infrared spectra (0.7-2.55 m) to identify the parent body of the H chondrites. We use a Bayesian inference model to confirm the meteorite analogs of the three asteroids. Based on our Bayes classifier we find the following analogs and probabilities: Juno is likely H chondrite (89%), Iris is likely LL chondrite (97.5%), and Phocaea is likely H chondrite (98.6%). While Phocaea has the highest probability of being an H chondrite, it is dynamically unlikely to deliver material to near-Earth space. While Juno has spectral properties similar to H chondrites, its family is unlikely to produce sizeable H-chondrite-type near-Earth objects (NEOs). If Juno is the primary source of H chondrite meteorites, it suggests that an additional source is needed to explain the H-chondrite-type NEOs.
PDF
