Niña Zambale Simon, Miguel Revilla, Nathaniel Hermosa
We propose a method to detect exoplanets based on their host star's intensity centroid after it passes thru a vortex filter. Based on our calculations with planets in face-on orbits, exoplanets with relative proximity to their host stars and with low mass ratios ($m_p/m_s$) can have discernible signals that can be amplified by the topological charge $\ell$ of the vortex filter. For exoplanets that have higher mass ratios and are far from their host stars, a clear signal can also be obtained but these are not affected by the value of $\ell$ and other planet detection methods may be more suitable. We present a simple table-top optical experiment to support our calculations. Our proposed method adds to the arsenal of techniques for astrometric exoplanet detection.
We present new Chandra X-ray observations of TAP 26, a ~17 Myr old magnetically-active weak-lined T Tauri star that has been reported to host a massive planet in a 10.8 day orbit. At a separation of a = 0.097 AU the planet will be exposed to intense X-ray and UV radiation from the star. The first observation caught the star in a state of elevated X-ray emission with variability on a timescale of a few hours and an X-ray temperature kTx ~ 2 - 4 keV. Two subsequent observations 5-10 days later showed slow variability and a lower X-ray flux and temperature (kTx ~ 1 keV). We characterize the X-ray emission and estimate the X-ray ionization and heating rates that will need to be incorporated into realistic models of the planet's atmosphere.
Based on radial velocities, EXORAP photometry, and activity indicators, the HADES team reported a 16.3-day rotation period for the M dwarf GJ 3942. However, an RV--H$α$ magnitude-squared coherence estimate has significant peaks at frequencies 1/16 cycles/day and 1/32 cycles/day. We re-analyze HADES data plus Hipparcos, SuperWASP, and TESS photometry to see whether the rotation period could be 32 days with 16-day harmonic. SuperWASP shows no significant periodicities, while the Hipparcos observing cadence is suboptimal for detecting 16- and 32-day periodicities. Although the average TESS periodogram has peaks at harmonics of 1/16 cycles/day, the harmonic sequence is not fully resolved according to the Rayleigh criterion. The TESS observations suggest a 1/16 cycles/day rotation frequency and a 1/32 cycles/day subharmonic, though resolution makes the TESS rotation detection ambiguous.
Spectroscopic observations of exoplanet atmospheres can reveal the chemical composition, temperature, cloud properties, and (potentially) the habitability of these distant worlds. The inference of such properties is generally enabled by Bayesian atmospheric retrieval algorithms. However, until recently, many retrieval codes have not been publicly available. Here, we describe the open source release of the POSEIDON exoplanet radiative transfer and retrieval code. POSEIDON is a Python package for the 1D, 2D, or 3D modelling and analysis of exoplanet spectra, which is frequently used to interpret Hubble and JWST observations of exoplanet atmospheres. We provide extensive tutorials on both forward modelling and retrievals in POSEIDON's online documentation, which we hope will serve as a helpful resource for the exoplanet atmosphere community.
The measurement of a diffuse astrophysical neutrino flux using starting track events marks the first time IceCube has observed and subsequently measured the astrophysical diffuse flux using a dataset composed primarily of starting track events. Starting tracks combine an excellent angular and energy resolution. This enables us to take advantage of the self-veto effect in the southern sky reducing the atmospheric neutrino rate allowing us to detect astrophysical neutrinos to energies well below 100 TeV. We measure the astrophysical flux as $\phi^{per-flavor}_{Astro}=1.68^{+0.19}_{-0.22}$(at 100 TeV) and $\gamma_{Astro} = 2.58^{+0.10}_{-0.09}$ assuming a single power law flux. The astrophysical flux 90% sensitive energy range is 3 TeV to 500 TeV, extending IceCube's reach to the low energy astrophysical flux by an order of magnitude. A brief summary of tests performed to search for neutrinos from the galactic plane using this dataset is also provided. With this sample, we did not find statistically significant evidence for emission from the galactic plane. We then tested the impact of these galactic plane neutrinos on the isotropic diffuse flux, with at most 10% effect on the overall normalization and negligible impact to the spectral index.
Tyler Baines, Néstor Espinoza, Joseph Filippazzo
et al.
In this report, we present the results of our analysis of trace position changes during NIRISS/SOSS observations. We examine the visit-to-visit impact of the GR700XD pupil wheel (PW) position alignment on trace positions for spectral orders 1 and 2 using the data obtained to date. Our goal is to improve the wavelength solution by correlating the trace positions on the detector with the PW position angle. We find that there is a one-to-one correspondence between PW position and spectral trace rotation for both orders. This allowed us in turn to find an analytic model that is able to predict a trace position/shape as a function of PW position with sub-pixel accuracy of about ~0.1 pixels. Such a function can be used to predict the trace position in low signal-to-noise ratio cases, and/or as a template to track trace position changes as function of time in Time Series Observations (TSOs).
Bruno Bertrand, Michal Cuadrat-Grzybowski, Pascale Defraigne
et al.
In this proceedings, we study the possible gravitational impact of primordial black holes (PBHs) or dark matter (DM) clumps on GNSS satellite orbits and gravimeter measurements. It provides a preliminary step to the future exhaustive statistical analysis over 28 years of gravimeter and GNSS data to get constraints over the density of asteroid-mass PBH and DM clumps inside the solar system. Such constraints would be the first to be obtained by direct observation on a terrestrial scale.
Daniels Collins, R. Guerraoui, J. Komatovic
et al.
We address the problem of online payments, where users can transfer funds among themselves. We introduce Astro, a system solving this problem efficiently in a decentralized, deterministic, and completely asynchronous manner. Astro builds on the insight that consensus is unnecessary to prevent double-spending. Instead of consensus, Astro relies on a weaker primitive---Byzantine reliable broadcast---enabling a simpler and more efficient implementation than consensus-based payment systems. In terms of efficiency, Astro executes a payment by merely broadcasting a message. The distinguishing feature of Astro is that it can maintain performance robustly, i.e., remain unaffected by a fraction of replicas being compromised or slowed down by an adversary. Our experiments on a public cloud network show that Astro can achieve near-linear scalability in a sharded setup, going from 10K payments/sec (2 shards) to 20K payments/sec (4 shards). In a nutshell, Astro can match VISA-level average payment throughput, and achieves a 5× improvement over a state-of-the-art consensus-based solution, while exhibiting sub-second 95^th percentile latency.
The IceCube Neutrino Observatory measured a flux of high-energy astrophysical neutrinos in several detection channels. The energy spectrum is fitted as unbroken power-law, but different best-fit parameters were obtained in the various analyses covering different energy ranges between few TeV to 10 PeV. Here, we present an update to the analysis of through-going muon-neutrinos from the Northern Hemisphere. It was extended to almost ten years of data and an improved treatment of systematic uncertainties on the atmospheric fluxes was implemented. The updated best-fit parameters for the astrophysical flux assuming a power-law energy spectrum are $\phi_{astro}=1.44$ and $\gamma_{astro}=2.28$. We will present the results of the spectral fit and discuss how the measured flux compares to other IceCube results.
Given the fact that Earth is so far the only place in the Milky Way galaxy known to harbor life, the question arises of whether the solar system is in any way special. To address this question, I compare the solar system to the many recently discovered exoplanetary systems. I identify two main features that appear to distinguish the solar system from the majority of other systems: (i) the lack of super-Earths, (ii) the absence of close-in planets. I examine models for the formation of super-Earths, as well as models for the evolution of asteroid belts, the rate of asteroid impacts on Earth, and of snow lines, all of which may have some implications for the emergence and evolution of life on a terrestrial planet. Finally, I revisit an argument by Brandon Carter on the rarity of intelligent civilizations, and I review a few of the criticisms of this argument.
We report on the design and construction of a microlens-array (MLA)-based pupil slicer and double scrambler for MAROON-X, a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. We have constructed a 3X slicer based on a single cylindrical MLA and show that geometric efficiencies of >85% can be achieved, limited by the fill factor and optical surface quality of the MLA. We present here the final design of the 3x pupil slicer and double scrambler for MAROON-X, based on a dual MLA design with (a)spherical lenslets. We also discuss the techniques used to create a pseudo-slit of rectangular core fibers with low FRD levels.
We present new kinetics data on the radiolytic destruction of amino acids measured in situ with infrared spectroscopy. Samples were irradiated at 15, 100, and 140 K with 0.8-MeV protons, and amino-acid decay was followed at each temperature with and without H$_2$O present. Observed radiation products included CO$_2$ and amines, consistent with amino-acid decarboxylation. The half-lives of glycine, alanine, and phenylalanine were estimated for various extraterrestrial environments. Infrared spectral changes demonstrated the conversion from the non-zwitterion structure NH$_2$-CH$_2$(R)-COOH at 15 K to the zwitterion structure $^+$NH$_3$-CH$_2$(R)-COO$^-$ at 140 K for each amino acid studied.
This review addresses the state of research that employs astronomical (remote sensing) observations of solids ("dust") in young circumstellar disks to learn about planet formation. The intention is for it to serve as an accessible, introductory, pedagogical resource for junior scientists interested in the subject. After some historical background and a basic observational primer, the focus is shifted to the three fundamental topics that broadly define the field: (1) demographics -- the relationships between disk properties and the characteristics of their environments and hosts; (2) structure -- the spatial distribution of disk material and its associated physical conditions and composition; and (3) evolution -- the signposts of key changes in disk properties, including the growth and migration of solids and the impact of dynamical interactions with young planetary systems. Based on the state of the art results in these areas, suggestions are made for potentially fruitful lines of work in the near future.
The CoRoT and Kepler satellites were the first space platforms designed to perform high-precision photometry for a large number of stars. Multiple systems display a wide variety of photometric variability, making them natural benefactors of these missions. I review the work arising from CoRoT and Kepler observations of multiple systems, with particular emphasis on eclipsing binaries containing giant stars, pulsators, triple eclipses and/or low-mass stars. Many more results remain untapped in the data archives of these missions, and the future holds the promise of K2, TESS and PLATO.
There is a widely held view in the astronomical community that unmanned robotic space vehicles are, and will always be, more efficient explorers of planetary surfaces than astronauts (e.g. Coates, 2001; Clements 2009; Rees 2011). Partly this is due to a common assumption that robotic exploration is cheaper than human exploration (although, as we shall see, this isn't necessarily true if like is compared with like), and partly from the expectation that continued developments in technology will relentlessly increase the capability, and reduce the size and cost, of robotic missions to the point that human exploration will not be able to compete. I will argue below that the experience of human exploration during the Apollo missions, more recent field analogue studies, and trends in robotic space exploration actually all point to exactly the opposite conclusion.