المؤلفون: Chen, Christine H., Lu, Cicero X., Worthen, Kadin, Law, David R., Sargent, B. A., Moro-Martin, Amaya, Sloan, G. C., Lisse, Carey M., Watson, Dan M., Girard, Julien H., Chair, Yiwei, Hines, Dean C., Kammerer, Jens, Li, Alexis, Perrin, Marshall, Pueyo, Laurent, Rebollido, Isabel, Stapelfeldt, Karl R., Stark, Christopher, Werner, Michael W.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: Modeling observations of the archetypal debris disk around $\beta$ Pic, obtained in 2023 January with the MIRI MRS on board JWST, reveals significant differences compared with that obtained with the IRS on board Spitzer. The bright 5 - 15 $\mu$m continuum excess modeled using a $\sim$600 K black body has disappeared. The previously prominent 18 and 23 $\mu$m crystalline forsterite emission features, arising from cold dust ($\sim$100 K) in the Rayleigh limit, have disappeared and been replaced by very weak features arising from the hotter 500 K dust population. Finally, the shape of the 10 $\mu$m silicate feature has changed, consistent with a shift in the temperature of the warm dust population from $\sim$300 K to $\sim$500 K and an increase in the crystalline fraction of the warm, silicate dust. Stellar radiation pressure may have blown both the hot and the cold crystalline dust particles observed in the Spitzer spectra out of the planetary system during the intervening 20 years between the Spitzer and JWST observations. These results indicate that the $\beta$ Pic system has a dynamic circumstellar environment, and that periods of enhanced collisions can create large clouds of dust that sweep through the planetary system.
Comment: 15 pages, 8 figures, ApJ in press

الوصول الحر: http://arxiv.org/abs/2407.04661Test

المؤلفون: Worthen, Kadin, Chen, Christine H., Law, David R., Lu, Cicero X., Hoch, Kielan, Chai, Yiwei, Sloan, G. C., Sargent, B. A., Kammerer, Jens, Hines, Dean C., Rebollido, Isabel, Balmer, William O., Perrin, Marshall D., Watson, Dan M., Pueyo, Laurent, Girard, Julien H., Lisse, Carey M., Stark, Christopher C.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: We present JWST MIRI Medium Resolution Spectrograph (MRS) observations of the $\beta$ Pictoris system. We detect an infrared excess from the central unresolved point source from 5 to 7.5 $\mu$m which is indicative of dust within the inner $\sim$7 au of the system. We perform PSF subtraction on the MRS data cubes and detect a spatially resolved dust population emitting at 5 $\mu$m. This spatially resolved hot dust population is best explained if the dust grains are in the small grain limit (2$\pi$a$\ll$$\lambda$). The combination of unresolved and resolved dust at 5 $\mu$m could suggest that dust grains are being produced in the inner few au of the system and are then radiatively driven outwards, where the particles could accrete onto the known planets in the system $\beta$ Pic b and c. We also report the detection of an emission line at 6.986 $\mu$m that we attribute to be [Ar II]. We find that the [Ar II] emission is spatially resolved with JWST and appears to be aligned with the dust disk. Through PSF subtraction techniques, we detect $\beta$ Pic b at the 5$\sigma$ level in our MRS data cubes and present the first mid-IR spectrum of the planet from 5 to 7 $\mu$m. The planet's spectrum is consistent with having absorption from water vapor between 5 and 6.5 $\mu$m. We perform atmosphere model grid fitting on spectra and photometry of $\beta$ Pic b and find that the planet's atmosphere likely has a sub-stellar C/O ratio.
Comment: Accepted for Publication in ApJ

الوصول الحر: http://arxiv.org/abs/2401.16361Test

المؤلفون: Corrales, Lia, Stassun, Keivan G., Cunningham, Tim, Duvvuri, Girish, Drake, Jeremy J., Espaillat, Catherine, Feinstein, Adina D., Gallo, Elena, Gunther, Hans Moritz, King, George W., Kounkel, Marina, Lisse, Carey M., Montez Jr., Rodolfo, Principe, David A., Toala, Jesus A., Wolk, Scott J., Cilley, Raven, Daylan, Tansu, Karovska, Margarita, Pradhan, Pragati, Wheatley, Peter J., Yang, Jun

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: One of the key research themes identified by the Astro2020 decadal survey is Worlds and Suns in Context. The Advanced X-ray Imaging Satellite (AXIS) is a proposed NASA APEX mission that will become the prime high-energy instrument for studying star-planet connections from birth to death. This work explores the major advances in this broad domain of research that will be enabled by the AXIS mission, through X-ray observations of stars in clusters spanning a broad range of ages, flaring M-dwarf stars known to host exoplanets, and young stars exhibiting accretion interactions with their protoplanetary disks. In addition, we explore the ability of AXIS to use planetary nebulae, white dwarfs, and the Solar System to constrain important physical processes from the microscopic (e.g., charge exchange) to the macroscopic (e.g., stellar wind interactions with the surrounding interstellar medium).
Comment: This White Paper is part of a series commissioned for the AXIS Probe Concept Mission

الوصول الحر: http://arxiv.org/abs/2311.07674Test

المؤلفون: Sitko, Michael L., Russell, Ray W., Long, Zachary C., Assani, Korash, Pikhartova, Monika, Bayyari, Ammar, Grady, Carol A., Lisse, Carey M., Marengo, Massimo, Wisniewski, John P., Danchi, William

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: We have examined inter-night variability of K2-discovered Dippers that are not close to being viewed edge-on, as determined from previously-reported ALMA images, using the SpeX spectrograph and the NASA Infrared Telescope facility (IRTF). The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 (2MASS J16042165-2130284). Using the ratio of the fluxes between two successive nights, we find that for EPIC 204638512 and EPIC 205151387, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The wavelength-dependent extinction models of both EPIC 204638512 and EPIC 205151387 includes grains at least 500 microns in size, but lacks grains smaller than 0.25 microns. The change in extinction during the dips, and the timescale for these variations to occur, imply obscuration by the surface layers of the inner disks. The recent discovery of a highly mis-inclined inner disk in EPIC 204638512 is suggests that the variations in this disk system may point to due to rapid changes in obscuration by the surface layers of its inner disk, and that other face-on Dippers might have similar geometries. The He I line at 1.083 microns in EPIC 205151387 and EPIC 20463851 were seen to change from night to night, suggesting that we are seeing He I gas mixed in with the surface dust.
Comment: 13 pages, 6 figures, 2 tables

الوصول الحر: http://arxiv.org/abs/2304.04650Test

المؤلفون: Saywell, J. C., Carey, M. S., Light, P. S., Szigeti, S. S., Milne, A. R., Gill, K. S., Goh, M. L., Perunicic, V. S., Wilson, N. M., Macrae, C. D., Rischka, A., Everitt, P. J., Robins, N. P., Anderson, R. P., Hush, M. R., Biercuk, M. J.

المصدر: Nat Commun 14, 7626 (2023)

مصطلحات موضوعية: Quantum Physics, Physics - Atomic Physics

الوصف: Atom-interferometric quantum sensors could revolutionize navigation, civil engineering, and Earth observation. However, operation in real-world environments is challenging due to external interference, platform noise, and constraints on size, weight, and power. Here we experimentally demonstrate that tailored light pulses designed using robust control techniques mitigate significant error sources in an atom-interferometric accelerometer. To mimic the effect of unpredictable lateral platform motion, we apply laser-intensity noise that varies up to 20$\%$ from pulse-to-pulse. Our robust control solution maintains performant sensing, while the utility of conventional pulses collapses. By measuring local gravity, we show that our robust pulses preserve interferometer scale factor and improve measurement precision by 10$\times$ in the presence of this noise. We further validate these enhancements by measuring applied accelerations over a 200 $\mu g$ range up to 21$\times$ more precisely at the highest applied noise level. Our demonstration provides a pathway to improved atom-interferometric inertial sensing in real-world settings.
Comment: 15 pages, 7 figures

الوصول الحر: http://arxiv.org/abs/2303.03683Test

المؤلفون: Schwamb, Megan E., Jones, R. Lynne, Yoachim, Peter, Volk, Kathryn, Dorsey, Rosemary C., Opitom, Cyrielle, Greenstreet, Sarah, Lister, Tim, Snodgrass, Colin, Bolin, Bryce T., Inno, Laura, Bannister, Michele T., Eggl, Siegfried, Solontoi, Michael, Kelley, Michael S. P., Jurić, Mario, Lin, Hsing Wen, Ragozzine, Darin, Bernardinelli, Pedro H., Chesley, Steven R., Daylan, Tansu, Ďurech, Josef, Fraser, Wesley C., Granvik, Mikael, Knight, Matthew M., Lisse, Carey M., Malhotra, Renu, Oldroyd, William J., Thirouin, Audrey, Ye, Quanzhi

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: The Vera C. Rubin Observatory is expected to start the Legacy Survey of Space and Time (LSST) in early to mid-2025. This multi-band wide-field synoptic survey will transform our view of the solar system, with the discovery and monitoring of over 5 million small bodies.The final survey strategy chosen for LSST has direct implications on the discoverability and characterization of solar system minor planets and passing interstellar objects. Creating an inventory of the solar system is one of the four main LSST science drivers. The LSST observing cadence is a complex optimization problem that must balance the priorities and needs of all the key LSST science areas. To design the best LSST survey strategy, a series of operation simulations using the Rubin Observatory scheduler have been generated to explore the various options for tuning observing parameters and prioritizations. We explore the impact of the various simulated LSST observing strategies on studying the solar system's small body reservoirs. We examine what are the best observing scenarios and review what are the important considerations for maximizing LSST solar system science. In general, most of the LSST cadence simulations produce +/-5% or less variations in our chosen key metrics, but a subset of the simulations significantly hinder science returns with much larger losses in the discovery and light curve metrics.
Comment: Accepted to ApJS, 103 pages (including references), 43 figures, 9 Tables. Videos will be available in the online journal formatted and published version of the paper [v2.0 submission corrects the author list metadata from the arxiv initial submission and updates the abstract]

الوصول الحر: http://arxiv.org/abs/2303.02355Test

المؤلفون: Sinclair, James A., Lisse, Carey M., Orton, Glenn S., Krishnamoorthy, Meera, Fletcher, Leigh N., Hora, Joseph, Palotai, Csaba, Hayward, Thomas

المصدر: Icarus, Volume 394, article id. 115404 (2023)

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: We present a retrospective analysis of Earth-based mid-infrared observations of Jupiter capturing the aftermath of the impacts by Comet D/Shoemaker-Levy 9 (henceforth SL9) in July 1994 and the Wesley impactor in July 2009. While the atmospheric effects of both impacts have been reported previously, we were motivated to re-examine both events using consistent methods to enable robust, quantitative comparisons. We analyzed spectrophotometry and spectroscopy capturing both impacts using two independent analyses: 1) a least-squares search over a grid of candidate mineral species to determine the composition of impact residue and 2) a radiative transfer analysis to derive atmospheric information. We observe that the SL9 impact sites are enhanced in stratospheric CH4 emissions at 7.9 um, due to shock heating and adiabatic compression from plume re-entry, and from 8.5 - 11.5 um due to stratospheric NH3 emission and non-gaseous cometary material. We derive NH3 concentrations of 5.7 ppmv at 30 mbar. In new findings, we find that the SL9 impact sites also exhibit a non-gaseous emission feature at 18 - 19 um. The non-gaseous emission at 8.5 - 11.5 and 18 - 19 um emission is best reproduced by predominantly amorphous olivine and obsidian at similar abundances. The Wesley impact site exhibits enhanced emissions from 8.8 - 11.5 and 18 - 19 um. We found this could be reproduced by predominantly amorphous olivine and stratospheric NH3 at concentrations of 150 ppbv at 30 mbar. Stratospheric NH3 abundances are a factor of 40 higher in the SL9 impacts compared to the Wesley impact, which confirms the former reached deeper, NH3-richer altitudes of the atmosphere. The absence of silicas in the Wesley impact would place an upper limit of 10 km/s on the incident velocity and 9 degree on the entry angle of the impactor such that temperatures were insufficient to convert silicates.

الوصول الحر: http://arxiv.org/abs/2301.01347Test

المؤلفون: Wang, Sharon Xuesong, Latouf, Natasha, Plavchan, Peter, Cale, Bryson, Blake, Cullen, Artigau, Étienne, Lisse, Carey M., Gagné, Jonathan, Crass, Jonathan, Tanner, Angelle

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: Precise radial velocity (PRV) surveys are important for the search of Earth analogs around nearby bright stars. Such planets induce a small stellar reflex motion with RV amplitude of $\sim$10 cm/s. Detecting such a small RV signal poses important challenges to instrumentation, data analysis, and the precision of astrophysical models to mitigate stellar jitter. In this work, we investigate an important component in the PRV error budget - the spectral contamination from the Earth's atmosphere (tellurics). We characterize the effects of telluric absorption on the RV precision and quantify its contribution to the RV budget over time and across a wavelength range of 350 nm - 2.5$\mu$m. We investigate the effectiveness in mitigating tellurics using simulated spectra of a solar twin star with telluric contamination over a year's worth of observations, and we extracted the RVs using two commonly adopted algorithms: dividing out a telluric model before performing cross-correlation or Forward Modeling the observed spectrum incorporating a telluric model. We assume various degrees of cleanness in removing the tellurics, including mimicking the lack of accurate knowledge of the telluric lines by using a mismatched line profile to model the "observed" tellurics. We conclude that the RV errors caused by telluric absorption can be suppressed to close to or even below the photon-limited precision in the optical region, especially in the blue, around 1-10 cm/s. At red through near-infrared wavelengths, however, the residuals of tellurics can induce an RV error on the m/s level even under the most favorable assumptions for telluric removal, leading to significant systematic noise in the RV time series and periodograms. If the red-optical or near-infrared becomes critical in the mitigation of stellar activity, systematic errors from tellurics can be eliminated with a space mission such as EarthFinder.
Comment: 29 pages, 11 figures. AJ under review. Comments welcome

الوصول الحر: http://arxiv.org/abs/2206.07287Test

المؤلفون: Lu, Cicero X., Chen, Christine H., Sargent, B. A., Watson, Dan M., Lisse, Carey M., Green, Joel D., Sitko, Michael L., Mittal, Tushar, Lebouteiller, V., Sloan, G. C., Rebollido, Isabel, Hines, Dean C., Girard, Julien H., Werner, Michael W., Stapelfeldt, Karl R., Wu, Winston, Worthen, Kadin

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: While beta Pic is known to host silicates in ring-like structures, whether the properties of these silicate dust vary with stellocentric distance remains an open question. We re-analyze the beta Pictoris debris disk spectrum from the Spitzer Infrared Spectrograph (IRS) and a new IRTF/SpeX spectrum to investigate trends in Fe/Mg ratio, shape, and crystallinity in grains as a function of wavelength, a proxy for stellocentric distance. By analyzing a re-calibrated and re-extracted spectrum, we identify a new 18 micron forsterite emission feature and recover a 23 micron forsterite emission feature with a substantially larger line-to-continuum ratio than previously reported. We find that these prominent spectral features are primarily produced by small submicron-sized grains, which are continuously generated and replenished from planetesimal collisions in the disk and can elucidate their parent bodies' composition. We discover three trends about these small grains: as stellocentric distance increases, (1) small silicate grains become more crystalline (less amorphous), (2) they become more irregular in shape, and (3) for crystalline silicate grains, the Fe/Mg ratio decreases. Applying these trends to beta Pic's planetary architecture, we find that the dust population exterior to the orbits of beta Pic b and c differs substantially in crystallinity and shape. We also find a tentative 3-5 micron dust excess due to spatially unresolved hot dust emission close to the star. From our findings, we infer that the surfaces of large planetesimals are more Fe-rich and collisionally-processed closer to the star but more Fe-poor and primordial farther from the star.
Comment: 19 pages, 12 figures, Accepted for Publication in ApJ

الوصول الحر: http://arxiv.org/abs/2205.09138Test

المؤلفون: Lauer, Tod R., Postman, Marc, Spencer, John R., Weaver, Harold A., Stern, S. Alan, Gladstone, G. Randall, Binzel, Richard P., Britt, Daniel T., Buie, Marc W., Buratti, Bonnie J., Cheng, Andrew F., Grundy, W. M., Horányi, Mihaly, Kavelaars, J. J., Linscott, Ivan R., Lisse, Carey M., McKinnon, William B., McNutt, Ralph L., Moore, Jeffrey M., Núñez, Jorge I., Olkin, Catherine B., Parker, Joel W., Porter, Simon B., Reuter, Dennis C., Robbins, Stuart J., Schenk, Paul M., Showalter, Mark R., Singer, Kelsi N., Verbiscer, Anne. J., Young, Leslie A.

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics

الوصف: We used New Horizons LORRI images to measure the optical-band ($0.4\lesssim\lambda\lesssim0.9{\rm\mu m}$) sky brightness within a high galactic-latitude field selected to have reduced diffuse scattered light from the Milky Way galaxy (DGL), as inferred from the IRIS all-sky $100~\mu$m map. We also selected the field to significantly reduce the scattered light from bright stars (SSL) outside the LORRI field. Suppression of DGL and SSL reduced the large uncertainties in the background flux levels present in our earlier New Horizons COB results. The raw total sky level, measured when New Horizons was 51.3 AU from the Sun, is $24.22\pm0.80{\rm ~nW ~m^{-2} ~sr^{-1}}.$ Isolating the COB contribution to the raw total required subtracting scattered light from bright stars and galaxies, faint stars below the photometric detection-limit within the field, and the hydrogen plus ionized-helium two-photon continua. This yielded a highly significant detection of the COB at ${\rm 16.37\pm 1.47 ~nW ~m^{-2} ~sr^{-1}}$ at the LORRI pivot wavelength of 0.608 $\mu$m. This result is in strong tension with the hypothesis that the COB only comprises the integrated light of external galaxies (IGL) presently known from deep HST counts. Subtraction of the estimated IGL flux from the total COB level leaves a flux component of unknown origin at ${\rm 8.06\pm1.92 ~nW ~m^{-2} ~sr^{-1}}.$ Its amplitude is equal to the IGL.
Comment: Accepted for publication in the Astrophysical Journal Letters

الوصول الحر: http://arxiv.org/abs/2202.04273Test