Search

We present JWST/MIRI low-resolution spectroscopy ($4.75-14~\mu$m) of the first known substellar companion, Gliese 229 Bab, which was recently resolved into a tight binary brown dwarf. Previous atmospheric retrieval studies modeling Gliese 229 B as a single brown dwarf have reported anomalously high carbon-to-oxygen ratios (C/O) of $\approx 1.1$ using $1-5~\mu$m ground-based spectra. Here, we fit the MIRI spectrum of Gliese 229 Bab with a two-component binary model using the Sonora Elf Owl grid and additionally account for the observed $K$ band flux ratio of the binary brown dwarf. Assuming the two brown dwarfs share the same abundances, we obtain $\rm C/O=0.65\pm0.05$ and $\rm [M/H]=0.00^{+0.04}_{-0.03}$ as their abundances ($2\sigma$ statistical errors), which are fully consistent with the host star abundances. We also recover the same abundances if we fit the MIRI spectrum with a single brown dwarf model, indicating that binarity does not strongly affect inferred abundances from mid-infrared data when the $T_\rm{eff}$ are similar between components of the binary. We measure $T_\rm{eff}=900^{+78}_{-29}~$K and $T_\rm{eff}=775^{+20}_{-33}~$K for the two brown dwarfs. We find that the vertical diffusion coefficients of $\log{K_\rm{zz}} \approx4.0$ are identical between the two brown dwarfs and in line with $\log{K_\rm{zz}}$ values inferred for isolated brown dwarfs with similar $T_\rm{eff}$. Our results demonstrate the power of mid-infrared spectroscopy in providing robust atmospheric abundance measurements for brown dwarf companions and by extension, giant planets., Comment: Accepted to ApJL

We present the first broadband near- to mid-infrared (3-12 microns) transmission spectrum of the highly-irradiated (T_eq = 981 K) M dwarf rocky planet L 168-9 b (TOI-134 b) observed with the NIRSpec and MIRI instruments aboard JWST. We measure the near-infrared transit depths to a combined median precision of 20 ppm across the three visits in 54 spectroscopic channels with uniform widths of 60 pixels (~0.2 microns wide; R~100), and the mid-infrared transit depths to 61 ppm median precision in 48 wavelength bins (~0.15 microns wide; R~50). We compare the transmission spectrum of L 168-9 b to a grid of 1D thermochemical equilibrium forward models, and rule out atmospheric metallicities of less than 100x solar (mean molecular weights <4 g mol$^{-1}$) to 3-sigma confidence assuming high surface pressure (>1 bar), cloudless atmospheres. Based on photoevaporation models for L 168-9 b with initial atmospheric mass fractions ranging from 2-100%, we find that this planet could not have retained a primordial H/He atmosphere beyond the first 200 Myr of its lifetime. Follow-up MIRI eclipse observations at 15 microns could make it possible to confidently identify a CO2-dominated atmosphere on this planet if one exists., Comment: 19 pages, 11 figures, accepted for publication in The Astronomical Journal

We present a JWST NIRSpec transmission spectrum of the super-Earth exoplanet L 98-59 c. This small (R$_p=1.385\pm0.085$R$_\oplus$, M$_p=2.22\pm0.26$R$_\oplus$), warm (T$_\textrm{eq}=553$K) planet resides in a multi-planet system around a nearby, bright (J = 7.933) M3V star. We find that the transmission spectrum of L 98-59 c is featureless at the precision of our data. We achieve precisions of 22ppm in NIRSpec G395H's NRS1 detector and 36ppm in the NRS2 detector at a resolution R$\sim$200 (30 pixel wide bins). At this level of precision, we are able rule out primordial H$_2$-He atmospheres across a range of cloud pressure levels up to at least $\sim$0.1mbar. By comparison to atmospheric forward models, we also rule out atmospheric metallicities below $\sim$300$\times$ solar at 3$\sigma$ (or equivalently, atmospheric mean molecular weights below $\sim$10~g/mol). We also rule out pure methane atmospheres. The remaining scenarios that are compatible with our data include a planet with no atmosphere at all, or higher mean-molecular weight atmospheres, such as CO$_2$- or H$_2$O-rich atmospheres. This study adds to a growing body of evidence suggesting that planets $\lesssim1.5$R$_\oplus$ lack extended atmospheres., Comment: 21 Pages, 13 Figures; Accepted to AJ

GQ Lup B is one of the few substellar companions with a detected cicumplanetary disk, or CPD. Observations of the CPD suggest the presence of a cavity, possibly formed by an exo-satellite. Using the Keck Planet Imager and Characterizer (KPIC), a high contrast imaging suite that feeds a high resolution spectrograph (1.9-2.5 microns, R$\sim$35,000), we present the first dedicated radial velocity (RV) observations around a high-contrast, directly imaged substellar companion, GQ Lup B, to search for exo-satellites. Over 11 epochs, we find a best and median RV error of 400-1000 m/s, most likely limited by systematic fringing in the spectra due to transmissive optics within KPIC. With this RV precision, KPIC is sensitive to exomoons 0.6-2.8% the mass of GQ Lup B ($\sim 30 M_{\text{Jup}}$) at separations between the Roche limit and $65 R_{\text{Jup}}$, or the extent of the cavity inferred within the CPD detected around GQ Lup B. Using simulations of HISPEC, a high resolution infrared spectrograph planned to debut at W.M. Keck Observatory in 2026, we estimate future exomoon sensitivity to increase by over an order of magnitude, providing sensitivity to less massive satellites potentially formed within the CPD itself. Additionally, we run simulations to estimate the amount of material that different masses of satellites could clear in a CPD to create the observed cavity. We find satellite-to-planet mass ratios of $q > 2 \times 10^{-4}$ can create observable cavities and report a maximum cavity size of $\sim 51 \, R_{\text{Jup}}$ carved from a satellite., Comment: 15 pages, 5 figures

Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations of protoplanetary disks in the millimeter continuum have shown a variety of radial gaps, cavities, and spiral features. These substructures may be signposts for ongoing planet formation, and therefore these systems are promising targets for direct imaging planet searches in the near-infrared. To this end, we present results from a deep imaging survey in the $L'$-band (3.8 $\mu$m) with the Keck/NIRC2 vortex coronagraph to search for young planets in 43 disks with resolved features in the millimeter continuum or evidence for gaps/central cavities from their spectral energy distributions. Although we do not detect any new point sources, using the vortex coronagraph allows for high sensitivity to faint sources at small angular separations (down to ${\sim}$0$^{\prime\prime}$.1), allowing us to place strong upper limits on the masses of potential gas giant planets. We compare our mass sensitivities to the masses of planets derived using ALMA observations, and while we are sensitive to $\sim$1 M$_{Jup}$ planets in the gaps in some of our systems, we are generally not sensitive to planets of the masses expected from the ALMA observations. In addition to placing upper limits on the masses of gas giant planets that could be interacting with the dust in the disks to form the observed millimeter substructures, we are also able to map the micron-sized dust as seen in scattered light for 8 of these systems. Our large sample of systems also allows us to investigate limits on planetary accretion rates and disk viscosities., Comment: 23 pages, 14 figures, 3 tables, accepted for publication in AJ

Using Keck Planet Imager and Characterizer (KPIC) high-resolution ($R$~35000) spectroscopy from 2.29-2.49 $\mu$m, we present uniform atmospheric retrievals for eight young substellar companions with masses of ~10-30 $M_\textrm{Jup}$, orbital separations spanning ~50-360 au, and $T_\textrm{eff}$ between ~1500-2600 K. We find that all companions have solar C/O ratios, and metallicities, to within the 1-2$\sigma$ level, with the measurements clustered around solar composition. Stars in the same stellar associations as our systems have near-solar abundances, so these results indicate that this population of companions is consistent with formation via direct gravitational collapse. Alternatively, core accretion outside the CO snowline would be compatible with our measurements, though the high mass ratios of most systems would require rapid core assembly and gas accretion in massive disks. On a population level, our findings can be contrasted with abundance measurements for directly imaged planets with m<10 $M_\textrm{Jup}$, which show tentative atmospheric metal enrichment. In addition, the atmospheric compositions of our sample of companions are distinct from those of hot Jupiters, which most likely form via core accretion. For two companions with $T_\textrm{eff}$~1700-2000 K (kap And b and GSC 6214-210 b), our best-fit models prefer a non-gray cloud model with >3$\sigma$ significance. The cloudy models yield 2-3$\sigma$ lower $T_\textrm{eff}$ for these companions, though the C/O and [C/H] still agree between cloudy and clear models at the $1\sigma$ level. Finally, we constrain 12CO/13CO for three companions with the highest S/N data (GQ Lup b, HIP 79098 b, and DH Tau b), and report $v$sin($i$) and radial velocities for all companions., Comment: Accepted to ApJ, 52 pages, 20 figures

While load balancing in distributed-memory computing has been well-studied, we present an innovative approach to this problem: a unified, reduced-order model that combines three key components to describe "work" in a distributed system: computation, communication, and memory. Our model enables an optimizer to explore complex tradeoffs in task placement, such as increased parallelism at the expense of data replication, which increases memory usage. We propose a fully distributed, heuristic-based load balancing optimization algorithm, and demonstrate that it quickly finds close-to-optimal solutions. We formalize the complex optimization problem as a mixed-integer linear program, and compare it to our strategy. Finally, we show that when applied to an electromagnetics code, our approach obtains up to 2.3x speedups for the imbalanced execution.

Planets between the sizes of Earth and Neptune are the most common in the Galaxy, bridging the gap between the terrestrial and giant planets in our Solar System. Now that we are firmly in the era of JWST, we can begin to measure, in more detail, the atmospheres of these ubiquitous planets to better understand their evolutionary trajectories. The two planets in the TOI-836 system are ideal candidates for such a study, as they fall on either side of the radius valley, allowing for direct comparisons of the present-day atmospheres of planets that formed in the same environment but had different ultimate end states. We present results from the JWST NIRSpec G395H transit observation of the larger and outer of the planets in this system, TOI-836c (2.587 R$_{\oplus}$, 9.6 M$_{\oplus}$, T$_{\rm eq}$$\sim$665 K). While we measure average 30-pixel binned precisions of $\sim$24ppm for NRS1 and $\sim$43ppm for NRS2 per spectral bin, we do find residual correlated noise in the data, which we attempt to correct using the JWST Engineering Database. We find a featureless transmission spectrum for this sub-Neptune planet, and are able to rule out atmospheric metallicities $<$175$\times$ Solar in the absence of aerosols at $\lesssim$1 millibar. We leverage microphysical models to determine that aerosols at such low pressures are physically plausible. The results presented herein represent the first observation from the COMPASS (Compositions of Mini-Planet Atmospheres for Statistical Study) JWST program, which also includes TOI-836b and will ultimately compare the presence and compositions of atmospheres for 12 super-Earths/sub-Neptunes., Comment: 23 pages, 14 figures, 3 tables, accepted for publication in AJ

We present two transit observations of the ~870K, 1.7R$_E$ super-Earth TOI-836b with JWST NIRSpec/G395H, resulting in a 2.8-5.2$\mu$m transmission spectrum. Using two different reduction pipelines, we obtain a median transit depth precision of 34ppm for Visit 1 and 36ppm for Visit 2, leading to a combined precision of 25ppm in spectroscopic channels 30 pixels wide (~0.02$\mu$m). We find that the transmission spectrum from both visits is well fit by a zero-sloped line by fitting zero-sloped and sloped lines, as well as step functions to our data. Combining both visits, we are able to rule out atmospheres with metallicities <250xSolar for an opaque pressure level of 0.1 bar, corresponding to mean molecular weights to <6gmol$^{-1}$. We therefore conclude that TOI-836b does not have an H$_2$-dominated atmosphere, in possible contrast with its larger, exterior sibling planet, TOI-836c. We recommend that future proposals to observe small planets exercise caution when requiring specific numbers of transits to rule out physical scenarios, particularly for high metallicities and planets around bright host stars, as PandExo predictions appear to be more optimistic than that suggested by the gains from additional transits implied by our data., Comment: 18 pages, 7 figures, 3 tables. Accepted in the Astronomical Journal

Context.Spatially-resoved cicrumstellar disk spectrum and composition can provide valuable insights into the bulk composition of forming planets, as well as the mineralogical signatures that emerge during and after planet formation. Aims. We aim to systemically extract the RX~J1604.3-213010 (J1604 hereafter) protoplanetary disk in high-contrast imaging observations, and obtain its multi-band reflectance in visible to near-infrared wavelengths. Methods. We obtained coronagraphic observations of J1604 from the Keck Observatory's NIRC2 instrument, and archival data from the Very Large Telescope's SPHERE instrument. Using archival images to remove star light and speckles, we recovered the J1604 disk and obtained its surface brightness using forward modeling. Together with polarization data, we obtained the relative reflectance of the disk in $R$, $J$, $H$ ($H2$ and $H3$), $K$ ($K1$ and $K2$), and $L'$ bands spanning two years. Results. Relative to the J1604 star, the resolved disk has a reflectance of ${\sim}10^{-1}$~arcsec$^{-2}$ in $R$ through $H$ bands and ${\sim}10^{-2}$~arcsec$^{-2}$ in $K$ and $L'$ bands, showing a blue color. Together with other systems, we summarized the multi-band reflectance for 9 systems. We also identified varying disk geometry structure, and a shadow that vanished between June and August in 2015. Conclusions. Motivated by broad-band observations, the deployment of cutting-edge technologies could yield higher-resolution reflection spectra, thereby informing the dust composition of disks in scattered light in the future. With multi-epoch observations, variable shadows have the potential to deepen insights into the dynamic characteristics of inner disk regions., Comment: 13 pages, 6 figures

Previous attempts have been made to characterize the atmospheres of directly imaged planets at low-resolution (R$\sim$10s-100s), but the presence of clouds has often led to degeneracies in the retrieved atmospheric abundances with cloud opacity and temperature structure that bias retrieved compositions. In this study, we perform retrievals on the ultra-young ($\lesssim$ 5 Myr) directly imaged planet ROXs 42B b with both a downsampled low-resolution $JHK$-band spectrum from Gemini/NIFS and Keck/OSIRIS, and a high-resolution $K$-band spectrum from pre-upgrade Keck/NIRSPAO. Using the atmospheric retrieval framework of petitRADTRANS, we analyze both data sets individually and combined. We additionally fit for the stellar abundances and other physical properties of the host stars, a young M spectral type binary, using the SPHINX model grid. We find that the measured C/O, $0.50\pm0.05$, and metallicity, [Fe/H] = $-0.67\pm0.35$, for ROXs 42B b from our high-resolution spectrum agree with that of its host stars within 1$\sigma$. The retrieved parameters from the high-resolution spectrum are also independent of our choice of cloud model. In contrast, the retrieved parameters from the low-resolution spectrum show strong degeneracies between the clouds and the retrieved metallicity and temperature structure. When we retrieve on both data sets together, we find that these degeneracies are reduced but not eliminated, and the final results remain highly sensitive to cloud modeling choices. We conclude that high-resolution spectroscopy offers the most promising path for reliably determining atmospheric compositions of directly imaged companions independent of their cloud properties., Comment: Accepted to the Astronomical Journal, 25 pages, 12 figures, 3 tables

M dwarfs are common host stars to exoplanets but often lack atmospheric abundance measurements. Late-M dwarfs are also good analogs to the youngest substellar companions, which share similar $T_{\rm eff}\sim2300-2800~K$. We present atmospheric analyses for the M7.5 companion HIP 55507 B and its K6V primary star with Keck/KPIC high-resolution ($R\sim35,000$) $K$ band spectroscopy. First, by including KPIC relative radial velocities between the primary and secondary in the orbit fit, we improve the dynamical mass precision by 60% and find $M_B=88.0_{-3.2}^{+3.4}$ $M_{\rm Jup}$, putting HIP 55507 B above the stellar-substellar boundary. We also find that HIP 55507 B orbits its K6V primary star with $a=38^{+4}_{-3}$ AU and $e=0.40\pm0.04$. From atmospheric retrievals of HIP 55507 B, we measure $\rm [C/H]=0.24\pm0.13$, $\rm [O/H]=0.15\pm0.13$, and $\rm C/O=0.67\pm0.04$. Moreover, we strongly detect $\rm ^{13}CO$ ($7.8\sigma$ significance) and tentatively detect $\rm H_2^{18}O$ ($3.7\sigma$ significance) in companion's atmosphere, and measure $\rm ^{12}CO/^{13}CO=98_{-22}^{+28}$ and $\rm H_2^{16}O/H_2^{18}O=240_{-80}^{+145}$ after accounting for systematic errors. From a simplified retrieval analysis of HIP 55507 A, we measure $\rm ^{12}CO/^{13}CO=79_{-16}^{+21}$ and $\rm C^{16}O/C^{18}O=288_{-70}^{+125}$ for the primary star. These results demonstrate that HIP 55507 A and B have consistent $\rm ^{12} C/^{13}C$ and $\rm ^{16}O/^{18}O$ to the $<1\sigma$ level, as expected for a chemically homogeneous binary system. Given the similar flux ratios and separations between HIP 55507 AB and systems with young, substellar companions, our results open the door to systematically measuring $\rm ^{13}CO$ and $\rm H_2^{18}O$ abundances in the atmospheres of substellar or even planetary-mass companions with similar spectral types., Comment: Accepted to ApJ, 28 pages, 14 figures

We present high-resolution $K$-band emission spectra of the quintessential hot Jupiter HD 189733 b from the Keck Planet Imager and Characterizer (KPIC). Using a Bayesian retrieval framework, we fit the dayside pressure-temperature profile, orbital kinematics, mass-mixing ratios of H$_2$O, CO, CH$_4$, NH$_3$, HCN, and H$_2$S, and the $\rm ^{13}CO/^{12}CO$ ratio. We measure mass fractions of $\rm \log H_2O = -2.0^{+0.4}_{-0.4}$ and $\rm \log CO = -2.2^{+0.5}_{-0.5}$, and place upper limits on the remaining species. Notably, we find $\rm \log CH_4 < -4.5$ at 99\% confidence, despite its anticipated presence at the equilibrium temperature of HD 189733 b assuming local thermal equilibrium. We make a tentative ($\sim3\sigma$) detection of $\rm ^{13}CO$, and the retrieved posteriors suggest a $\rm ^{12}C/^{13}C$ ratio similar to or substantially less than the local interstellar value. The possible $\rm ^{13}C$ enrichment would be consistent with accretion of fractionated material in ices or in the protoplanetary disk midplane. The retrieved abundances correspond to a substantially sub-stellar atmospheric $\rm C/O = 0.3\pm0.1$, while the carbon and oxygen abundances are stellar to slightly super-stellar, consistent with core-accretion models which predict an inverse correlation between C/O and metallicity. The specific combination of low C/O and high metallicity suggests significant accretion of solid material may have occurred late in the formation process of HD 189733 b., Comment: 17 pages, 7 figures, 2 tables, accepted in AJ

Diverse protoplanetary disk morphology can result from planet-disk interaction, suggesting planetary presence. To date, most scattered light imaging campaigns have probed polarized light, which is only a fraction of the total light and not very sensitive to planets. To observe and characterize protoplanetary disk systems in the near-infrared in both polarized and total intensity light, we carried out an unprecedented study of scattering properties of disks, as well as of any planetary companions. Using SPHERE with star-hopping at the Very Large Telescope, we observed 29 disk hosts and their reference stars in $K_s$-band polarized light. We extracted disks in total intensity by adopting the data imputation concept with sequential non-negative matrix factorization (DI-sNMF). We obtained high-quality disk images in total intensity for 15 systems and in polarized light for 23. For well-recovered disks in polarized light and total intensity, we parameterized the polarization fraction phase functions using scaled beta distribution: the peak of polarization fraction tentatively correlates with the peak scattering angle, which could be reproduced using certain compact dust, yet more detailed modeling studies are needed. We investigated the empirical DI-sNMF detectability of disks using logistic regression: total intensity detectability of disks primarily depends on host star brightness. For disks with SPHERE data in $Y$-/$J$-/$H$-band, we summarized their polarized color at ~90 deg scattering angle: most of disks are blue in polarized $J-K_s$ color, and they are relatively redder as stellar luminosity increases, indicating larger scatterers. High-quality disk imagery in both total intensity and polarized light thus allows for disk characterization in polarization fraction, and reduces the confusion between disk and planetary signals., Comment: 25 pages, 16 figures, 3 tables, A&A accepted. Data files in FITS format will be publicly available

In the rapid evolution of next-generation brain-inspired artificial intelligence and increasingly sophisticated electromagnetic environment, the most bionic characteristics and anti-interference performance of spiking neural networks show great potential in terms of computational speed, real-time information processing, and spatio-temporal information processing. Data processing. Spiking neural network is one of the cores of brain-like artificial intelligence, which realizes brain-like computing by simulating the structure and information transfer mode of biological neural networks. This paper summarizes the strengths, weaknesses and applicability of five neuronal models and analyzes the characteristics of five network topologies; then reviews the spiking neural network algorithms and summarizes the unsupervised learning algorithms based on synaptic plasticity rules and four types of supervised learning algorithms from the perspectives of unsupervised learning and supervised learning; finally focuses on the review of brain-like neuromorphic chips under research at home and abroad. This paper is intended to provide learning concepts and research orientations for the peers who are new to the research field of spiking neural networks through systematic summaries.

The Vera C. Rubin Observatory will undertake the Legacy Survey of Space and Time, providing an unprecedented, volume-limited catalog of star clusters in the Southern Sky, including Galactic and extragalactic star clusters. The Star Clusters subgroup of the Stars, Milky Way and Local Volume Working Group has identified key areas where Rubin Observatory will enable significant progress in star cluster research. This roadmap represents our science cases and preparation for studies of all kinds of star clusters from the Milky Way out to distances of tens of megaparsecs., Comment: accepted to PASP

We present Keck/KPIC high-resolution ($R\sim35,000$) $K$-band thermal emission spectroscopy of the ultra-hot Jupiter WASP-33b. The use of KPIC's single-mode fibers greatly improves both blaze and line-spread stabilities relative to slit spectrographs, enhancing the cross-correlation detection strength. We retrieve the dayside emission spectrum with a nested sampling pipeline which fits for orbital parameters, the atmospheric pressure-temperature profile, and molecular abundances.We strongly detect the thermally-inverted dayside and measure mass-mixing ratios for CO ($\log\rm CO_{MMR} = -1.1^{+0.4}_{-0.6}$), H$_2$O ($\log\rm H_2O_{MMR} = -4.1^{+0.7}_{-0.9}$) and OH ($\log\rm OH_{MMR} = -2.1^{+0.5}_{-1.1}$), suggesting near-complete dayside photodissociation of H$_2$O. The retrieved abundances suggest a carbon- and possibly metal-enriched atmosphere, with a gas-phase C/O ratio of $0.8^{+0.1}_{-0.2}$, consistent with the accretion of high-metallicity gas near the CO$_2$ snow line and post-disk migration or with accretion between the soot and H$_2$O snow lines. We also find tentative evidence for $\rm ^{12}CO/^{13}CO \sim 50$, consistent with values expected in protoplanetary disks, as well as tentative evidence for a metal-enriched atmosphere (2--15$\times$ solar). These observations demonstrate KPIC's ability to characterize close-in planets and the utility of KPIC's improved instrumental stability for cross-correlation techniques., Comment: Accepted in AJ, 26 pages, 12 figures

Carbon monoxide (CO) is predicted to be the dominant carbon-bearing molecule in giant planet atmospheres, and, along with water, is important for discerning the oxygen and therefore carbon-to-oxygen ratio of these planets. The fundamental absorption mode of CO has a broad double-branched structure composed of many individual absorption lines from 4.3 to 5.1 $\mathrm{\mu}$m, which can now be spectroscopically measured with JWST. Here we present a technique for detecting the rotational sub-band structure of CO at medium resolution with the NIRSpec G395H instrument. We use a single transit observation of the hot Jupiter WASP-39b from the JWST Transiting Exoplanet Community Early Release Science (JTEC ERS) program at the native resolution of the instrument ($R \,{\sim} 2700$) to resolve the CO absorption structure. We robustly detect absorption by CO, with an increase in transit depth of 264 $\pm$ 68 ppm, in agreement with the predicted CO contribution from the best-fit model at low resolution. This detection confirms our theoretical expectations that CO is the dominant carbon-bearing molecule in WASP-39b's atmosphere, and further supports the conclusions of low C/O and super-solar metallicities presented in the JTEC ERS papers for WASP-39b., Comment: 11 pages, 5 figures, accepted for publication in ApJL

Planet formation imprints signatures on the physical structures of disks. In this paper, we present high-resolution ($\sim$50 mas, 8 au) Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.3 mm dust continuum and CO line emission toward the disk around the M3.5 star 2MASS J04124068+2438157. The dust disk consists only of two narrow rings at radial distances of 0.47 and 0.78 arcsec ($\sim$70 and 116 au), with Gaussian $\sigma$ widths of 5.6 and 8.5 au, respectively. The width of the outer ring is smaller than the estimated pressure scale height by $\sim25\%$, suggesting dust trapping in a radial pressure bump. The dust disk size, set by the location of the outermost ring, is significantly larger (by $3\sigma$) than other disks with similar millimeter luminosity, which can be explained by an early formation of local pressure bump to stop radial drift of millimeter dust grains. After considering the disk's physical structure and accretion properties, we prefer planet--disk interaction over dead zone or photoevaporation models to explain the observed dust disk morphology. We carry out high-contrast imaging at $L'$ band using Keck/NIRC2 to search for potential young planets, but do not identify any source above $5\sigma$. Within the dust gap between the two rings, we reach a contrast level of $\sim$7 mag, constraining the possible planet below $\sim$2--4 $M_{\rm Jup}$. Analyses of the gap/ring properties suggest a $\sim$Saturn mass planet at $\sim$90 au is likely responsible for the formation of the outer ring, which can be potentially revealed with JWST., Comment: 15 pages, 5 figures. Accepted for publication in ApJ

Gaps in circumstellar disks can signal the existence of planetary perturbers, making such systems preferred targets for direct imaging observations of exoplanets. Being one of the brightest and closest stars to the Sun, the photometric standard star Vega hosts a two-belt debris disk structure. Together with the fact that its planetary system is being viewed nearly face-on, Vega has been one of the prime targets for planet imaging efforts. Using the vector vortex coronagraph on Keck/NIRC2 in Ms-band at 4.67 $\mu$m, we report the planet detection limits from 1 au to 22 au for Vega with an on-target time of 1.8 h. We reach a 3 Jupiter mass limit exterior to 12 au, which is nearly an order of magnitude deeper than existing studies. Combining with existing radial velocity studies, we can confidently rule out the existence of companions more than ~8 Jupiter mass from 22 au down to 0.1 au for Vega. Interior and exterior to ~4 au, this combined approach reaches planet detection limits down to ~2-3 Jupiter mass using radial velocity and direct imaging, respectively. By reaching multi-Jupiter mass detection limits, our results are expected to be complemented by the planet imaging of Vega in the upcoming observations using the James Webb Space Telescope to obtain a more holistic understanding of the planetary system configuration around Vega., Comment: 6 pages, 3 figures, 1 table, A&A accepted. Contrast curve for 2018 observation available in anc folder. Happy Rabbit Year!

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; Kmag=13; 0.7" separation) with the Keck Planet Imager and Characterizer (KPIC; R~35,000 in 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 MODHIS, planned for the Thirty Meter Telescope, should be sensitive to satellites with mass ratios of ~1e-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., Comment: Accepted to AJ (Jan 10, 2023)

We study the emergent spectral fluxes of transiting hot Jupiters, using secondary eclipses from Spitzer. To achieve a large and uniform sample, we have re-analyzed all secondary eclipses for all hot Jupiters observed by Spitzer at 3.6- and/or 4.5 microns. Our sample comprises 457 eclipses of 122 planets, including eclipses of 13 planets not previously published. We use these eclipse depths to calculate the spectral fluxes emergent from the exoplanetary atmospheres, and thereby infer temperature and spectral properties of hot Jupiters. We find that an abrupt rise in brightness temperature, similar to a phase change, occurs on the day side atmospheres of the population at an equilibrium temperature between 1714K and 1818K (99-percent confidence limits). The amplitude of the rise is 291 +/-49 Kelvins, and two viable causes are the onset of magnetic drag that inhibits longitudinal heat redistribution, and/or the rapid dissipation of day side clouds. We also study hot Jupiter spectral properties with respect to metallicity and temperature inversions. Models exhibiting 4.5 micron emission from temperature inversions reproduce our fluxes statistically for the hottest planets, but the transition to emission is gradual, not abrupt. The Spitzer fluxes are sensitive to metallicity for planets cooler than approximately 1200 Kelvins, and most of the hot Jupiter population falls between model tracks having solar to 30X-solar metallicity., Comment: 29 pages, 12 figures, 4 tables (3 are MR), accepted for the Astronomical Journal

Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability. However, no unambiguous photochemical products have been detected in exoplanet atmospheres to date. Recent observations from the JWST Transiting Exoplanet Early Release Science Program found a spectral absorption feature at 4.05 $\mu$m arising from SO$_2$ in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M$_J$) gas giant exoplanet orbiting a Sun-like star with an equilibrium temperature of $\sim$1100 K. The most plausible way of generating SO$_2$ in such an atmosphere is through photochemical processes. Here we show that the SO$_2$ distribution computed by a suite of photochemical models robustly explains the 4.05 $\mu$m spectral feature identified by JWST transmission observations with NIRSpec PRISM (2.7$\sigma$) and G395H (4.5$\sigma$). SO$_2$ is produced by successive oxidation of sulphur radicals freed when hydrogen sulphide (H$_2$S) is destroyed. The sensitivity of the SO$_2$ feature to the enrichment of the atmosphere by heavy elements (metallicity) suggests that it can be used as a tracer of atmospheric properties, with WASP-39b exhibiting an inferred metallicity of $\sim$10$\times$ solar. We further point out that SO$_2$ also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations., Comment: 39 pages, 14 figures, accepted to be published in Nature

Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking the formation and evolution of exoplanetary systems. Access to an exoplanet's chemical inventory requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based and high-resolution ground-based facilities. Here we report the medium-resolution (R$\sim$600) transmission spectrum of an exoplanet atmosphere between 3-5 $\mu$m covering multiple absorption features for the Saturn-mass exoplanet WASP-39b, obtained with JWST NIRSpec G395H. Our observations achieve 1.46x photon precision, providing an average transit depth uncertainty of 221 ppm per spectroscopic bin, and present minimal impacts from systematic effects. We detect significant absorption from CO$_2$ (28.5$\sigma$) and H$_2$O (21.5$\sigma$), and identify SO$_2$ as the source of absorption at 4.1 $\mu$m (4.8$\sigma$). Best-fit atmospheric models range between 3 and 10x solar metallicity, with sub-solar to solar C/O ratios. These results, including the detection of SO$_2$, underscore the importance of characterising the chemistry in exoplanet atmospheres, and showcase NIRSpec G395H as an excellent mode for time series observations over this critical wavelength range., Comment: 44 pages, 11 figures, 3 tables. Resubmitted after revision to Nature

Abnormalities in motor-control behavior, which have been with concussion and head acceleration events (HAE), can be quantified using virtual reality (VR) technologies. Motor-control behavior has been consistently mapped to the brain's somatomotor network (SM) using both structural (sMRI) and functional MRI (fMRI). However, no studies habe integrated HAE, motor-control behavior, sMRI and fMRI measures. Here, brain networks important for motor-control were hypothesized to show changes in tractography-based diffusion weighted imaging [difference in fractional anisotropy (dFA)] and resting-state fMRI (rs-fMRI) measures in collegiate American football players across the season, and that these measures would relate to VR-based motor-control. We firther tested if nine inflammation-related miRNAs were associated with behavior-structure-function variables. Using permutation-based mediation and moderation methods, we found that across-season dFA from the SM structural connectome (SM-dFA) mediated the relationship between across-season VR-based Sensory-motor Reactivity (dSR) and rs-fMRI SM fingerprint similarity (p = 0.007 and Teff = 47%). The interaction between dSR and SM-dFA also predicted (pF = 0.036, pbeta3 = 0.058) across-season levels of dmiRNA-30d through permutation-based moderation analysis. These results suggest (1) that motor-control is in a feedback relationship with brain structure and function, (2) behavior-structure-function can be connected to HAE, and (3) behavior-structure might predict molecular biology measures., Comment: 62 pages, 4 figures, 2 tables

The formation and evolution pathway for the directly-imaged multi-planetary 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$\sim$20-35,000). We specifically retrieve [C/H], [O/H], and C/O and find them to be 0.55$^{+0.36}_{-0.39}$, 0.47$^{+0.31}_{-0.32}$, and 0.67$^{+0.12}_{-0.15}$ at 68\% confidence. The super-stellar 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 $\sim$1 Myr), followed by further atmospheric enrichment in C and O through the accretion of solids beyond the CO iceline. The enrichment either preceded or took place during the early phase of the inward migration to the planet current locations., Comment: 19 pages, 6 figures, 3 tables, accepted to AAS journals

Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (i.e., elements heavier than helium, also called "metallicity"), and thus formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2 but have not yielded definitive detections due to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science Program (ERS). The data used in this study span 3.0 to 5.5 {\mu}m in wavelength and show a prominent CO2 absorption feature at 4.3 {\mu}m (26{\sigma} significance). The overall spectrum is well matched by one-dimensional, 10x solar metallicity models that assume radiative-convective-thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide, and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 {\mu}m that is not reproduced by these models., Comment: 27 pages, 6 figures, Accepted for publication in Nature, data and models available at https://doi.10.5281/zenodo.6959427