Year: 2024
Type: article
Abstract: We present images of the Vega planetary debris disk obtained at 15.5, 23, and 25.5 μm with the Mid-Infrared Instrument on JWST. The debris system is remarkably symmetric, smooth, and centered accurately on the star. There is a broad Kuiper-belt-analog ring at ∼80–170 au that coincides with the planetesimal belt detected with the Atacama Large Millimeter/submillimeter Array at 1.34 mm. The interior of the broad belt is filled with warm debris that shines most efficiently at mid-infrared, along with a shallow flux dip/gap at 60 au from the star. These qualitative characteristics argue against any Saturn-mass planets orbiting the star outside of about 10 au, assuming the unseen planet would be embedded in the very broad planetesimal disk from a few to hundreds of astronomical units. We find that the distribution of dust detected interior to the broad outer belt is consistent with grains being dragged inward by the Poynting–Robertson effect. Under the drag-dominated disk assumption, tighter constraints can be derived for planets in specific locations; for example, any planet shepherding the inner edge of the outer belt is likely to be less than six Earth masses. The disk surface brightness profile along with the available infrared photometry suggest a disk inner edge near ∼3−5 au, disconnected from the sub-astronomical-unit region that gives rise to the hot near-infrared excess. The gap between the hot, sub-astronomical-unit zone and the inner edge of the warm debris might be shepherded by a modest-mass, Neptune-size planet.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G103270039, G1632446036, G256731684, G3152952368, THE OBJECTIVES OF THIS RESEARCH ARE TO IMPROVE OUR UNDERSTANDING OF THE DYNAMICAL ARCHITECTURES OF PLANETARY SYSTEMS AND THE OVERALL MASS DISTRIBUTION OF PLANETS IN THE GALAXY BY USING AVAILABLE EXOPLANET OBSERVATIONAL DATA SETS IN CONCERT WITH THEORY AND MODELING OF THEIR ORBITAL DYNAMICS. OBSERVATIONAL DATA SETS OF EXOPLANETS ARE EXPANDING RAPIDLY (THANKS TO NASA MISSIONS SUCH AS KEPLER AND THE FORTHCOMING JWST TESS AND WFIRST) BUT THEIR THEORETICAL INTERPRETATION HAS SIGNIFICANTLY LAGGED. EXOPLANET DETECTION AND CONFIRMATION PIPELINES NOW ROUTINELY CHECK WHETHER THE PLANETARY SYSTEMS THEY DISCOVER ARE LIKELY TO BE DYNAMICALLY STABLE. AT THE SAME TIME IT IS INCREASINGLY RECOGNIZED THAT OBSERVED PLANETARY ARCHITECTURES ARE OFTEN QUITE CLOSE TO THE EDGE OF DYNAMICAL STABILITY". IN THE FIRST PROJECT WE WILL APPLY THE TOOLS OF N-BODY NUMERICAL SIMULATIONS TO OBSERVED CLOSE-IN MULTI-PLANET SYSTEMS DISCOVERED BY KEPLER TO ASSESS THEIR DISTRIBUTION OF DYNAMICAL INSTABILITY LIFETIMES. WE WILL IDENTIFY THE COMMON SIGNS OF IMMINENT INSTABILITY AS WELL AS COMMON SIGNS OF LONGEVITY FOR PLANETARY SYSTEMS ON THE EDGE OF DYNAMICAL STABILITY. THIS PROJECT WILL PRODUCE PREDICTIONS OF THE DISTRIBUTION OF STABLE PLANETARY ARCHITECTURES TESTABLE BY FUTURE LARGE SAMPLES OF MULTI-PLANET SYSTEMS SUCH AS THOSE OBSERVED BY THE FORTHCOMING TESS SURVEY. IN THE SECOND PROJECT WE WILL CONTINUE WITH NUMERICAL SIMULATIONS OF UNSTABLE SYSTEMS TO ASSESS POST-INSTABILITY PLANETARY ARCHITECTURES. IT HAS BEEN SUGGESTED THAT MULTI-PLANET SYSTEMS WITH FEWER MORE WIDELY SPACED PLANETS COULD BE THE RESULT OF COLLISIONS BETWEEN PLANETS IN ORIGINALLY MORE TIGHTLY PACKED SYSTEMS. BY MODELING TWO DIFFERENT SCENARIOS OF COLLISION OUTCOMES (THAT COLLISIONS ARE EITHER DESTRUCTIVE OR MOSTLY ACCRETIONAL) WE WILL GENERATE SIMULATED DISTRIBUTIONS OF POST-INSTABILITY PLANETARY SYSTEMS ARISING FROM A VARIETY OF PRE-INSTABILITY PLANETARY ARCHITECTURES; COMPARISON WITH THE OBSERVED KEPLER PLANETARY SYSTEMS WILL TEST THE IDEA THAT A FRACTION OF THE OBSERVED SYSTEMS UNDERWENT PAST INSTABILITIES. THIS PROJECT WILL ALSO PROVIDE PREDICTIONS FOR THE FREQUENCY OF PLANET-PLANET COLLISIONS AROUND DWARF STARS AS A FUNCTION OF SYSTEM AGE TO BE COMPARED WITH THE OBSERVED FREQUENCY OF INFRARED-EXCESSES AROUND DWARF STARS. IN THE THIRD PROJECT WE WILL CONSIDER ANEW THE RELATIONSHIP BETWEEN ORBITAL SEPARATIONS AND PLANETARY MASSES IN MARGINALLY STABLE MULTIPLE PLANET SYSTEMS AND DERIVE AN IMPROVED ESTIMATE OF THE PLANET MASS DISTRIBUTION FUNCTION. WHILE VARIOUS PREVIOUS STUDIES HAVE TAKEN A DETERMINISTIC APPROACH TO COMPUTE DYNAMICAL LIFETIMES AS A FUNCTION OF THE DIMENSIONLESS "DYNAMICAL SEPARATION" (ORBITAL SPACING IN UNITS OF THE MUTUAL HILL RADIUS OF TWO ADJACENT PLANETS) WE PROPOSE A STATISTICAL APPROACH USING THE RESULTS OF OUR FIRST TWO PROJECTS TO CHARACTERIZE THE DISTRIBUTION OF DYNAMICAL SEPARATIONS AS A FUNCTION OF DYNAMICAL LIFETIMES IN DIVERSE PLANETARY SYSTEMS. WITH THESE RESULTS IN HAND WE WILL LEVERAGE THE KEPLER DATASET OF WELL DETERMINED ORBITAL PERIODS IN HUNDREDS OF MULTIPLE PLANET SYSTEMS TO PREDICT THE OVERALL MASS DISTRIBUTION FUNCTION OF CLOSE-IN PLANETS. OUR PREDICTED MASS DISTRIBUTION FUNCTION WILL BE OBSERVATIONALLY TESTABLE BY BOTH THE FORTHCOMING TESS TRANSITING PLANET SAMPLE AND BY THE FUTURE WFIRST MISCROLENSING PLANET SAMPLE. OUR PROPOSED INVESTIGATIONS ARE RELEVANT TO XRP BECAUSE THEY INCORPORATE THEORY AND MODELING TO FACILITATE INTERPRETATION OF OBSERVATIONAL DATA FROM NASA'S KEPLER SPACE MISSION AND THEY WILL MAKE TESTABLE PREDICTIONS FOR FORTHCOMING EXOPLANET SURVEYS AS WELL AS SURVEYS OF INFRARED EXCESSES ASSOCIATED WITH PLANET-PLANET COLLISIONS. OUR PROPOSED STUDIES WILL IMPROVE UNDERSTANDING OF THE ORIGINS OF OBSERVED EXOPLANETARY SYSTEMS BY CHARACTERIZING THEIR ORBITAL DYNAMICS., G5568641063, 1. SCIENCE INVESTIGATION: SUMMARY IN MY ORIGINAL PROPOSAL WRITTEN PRIOR TO THE LAUNCH OF SPITZER I PLANNED A JWST PROGRAM ON ACTIVE GALACTIC NUCLEI (AGN) AND THEIR HOST GALAXIES BUILDING ON THEN-FUTURE SPITZER OBSERVATIONS. TOWARD THE END OF THE SPITZER COLD MISSION AS THE PI FOR THE MIPS INSTRUMENT I HAD LED SUBSTANTIAL PROGRAMS ON BOTH EXTRAGALACTIC OBSERVATIONS AND DEBRIS DISKS SO I PROPOSED TO EXPAND MY JWST EFFORT TO INCLUDE BOTH AN EXPANSION THAT WAS APPROVED BY ED WEILER ON OCTOBER 16 2009. THE FOLLOWING PROGRAM THEREFORE INCLUDES BOTH OF THESE THEMES. SINCE BOTH PROPOSALS WERE WRITTEN MAJOR NEW CAPABILITIES HAVE ANSWERED SOME OF THE PREVIOUS SCIENTIFIC QUESTIONS AND POSED NEW ONES. IN THE EXTRAGALACTIC ARENA THESE INCLUDE SPITZER ITSELF HERSCHEL THE EXPANDED CAPABILITIES OF THE JVLA AND ALMA. FOR DEBRIS DISKS THE MOST IMPORTANT ARE HERSCHEL ALMA AND HIGH PERFORMANCE ADAPTIVE OPTICS. THEREFORE THE MATERIAL IN THIS PROPOSAL IS RE-THOUGHT TO PROVIDE A PROGRAM AT THE CUTTING EDGE OF THE CURRENT PROBLEMS IN THESE AREAS. EACH OF THE INDIVIDUAL INVESTIGATIONS DESCRIBED BELOW IS DESCRIBED IN A DETAILED INTERNAL REPORT AND IS READY FOR DETAILED OBSERVATION PLANNING. THIS PROPOSAL GIVES A SUMMARY OF THE HIGH LEVEL GOALS AND REQUIRED OBSERVATIONS ONLY. IT INTENTIONALLY SOMEWHAT OVERSUBSCRIBES MY TIME ALLOTMENT TO ALLOW FOR COLLABORATIONS AND SHARED TIME AS WELL AS FURTHER OPTIMIZATION. ALTHOUGH THERE ARE A NUMBER OF INVESTIGATIONS MY RESEARCH GROUP HAS BEEN ACTIVE IN ALL OF THEM; I HAVE BOLD-FACED CITATIONS OF OUR RELEVANT WORK IN THE BIBLIOGRAPHY (ATTACHED AS APPENDIX A). IN ADDITION I WAS ASSIGNED AN ADDITIONAL 60 HOURS OF GTO TIME TO BE DISTRIBUTED AMONG (MOSTLY) YOUNG SCIENTISTS IN THE UNITED STATES WHO HAD MADE MAJOR COMMITMENTS IN SUPPORT OF MIRI (ROUGHLY PARALLEL TO THE GTO TIME FOR MIRI SUPPORT BY THE EUROPEAN CONSORTIUM (EC)). APPENDIX C INCLUDES SHORT STATUS REPORTS ON THEIR PLANS., G6686480456, G7085798212
OpenAlex ID: W4405591420