Showing papers by "Geert Barentsen published in 2019"
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TL;DR: The Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-sized planets transiting L 98-59 (TOI-175, TIC 307210830) is reported in this article.
Abstract: We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-sized planets transiting L 98-59 (TOI-175, TIC 307210830) -- a bright M dwarf at a distance of 10.6 pc. Using the Gaia-measured distance and broad-band photometry we find that the host star is an M3 dwarf. Combined with the TESS transits from three sectors, the corresponding stellar parameters yield planet radii ranging from 0.8REarth to 1.6REarth. All three planets have short orbital periods, ranging from 2.25 to 7.45 days with the outer pair just wide of a 2:1 period resonance. Diagnostic tests produced by the TESS Data Validation Report and the vetting package DAVE rule out common false positive sources. These analyses, along with dedicated follow-up and the multiplicity of the system, lend confidence that the observed signals are caused by planets transiting L 98-59 and are not associated with other sources in the field. The L 98-59 system is interesting for a number of reasons: the host star is bright (V = 11.7 mag, K = 7.1 mag) and the planets are prime targets for further follow-up observations including precision radial-velocity mass measurements and future transit spectroscopy with the James Webb Space Telescope; the near resonant configuration makes the system a laboratory to study planetary system dynamical evolution; and three planets of relatively similar size in the same system present an opportunity to study terrestrial planets where other variables (age, metallicity, etc.) can be held constant. L 98-59 will be observed in 4 more TESS sectors, which will provide a wealth of information on the three currently known planets and have the potential to reveal additional planets in the system.
108 citations
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Search for extraterrestrial intelligence1, Goddard Space Flight Center2, University of Maryland, Baltimore3, University of Maryland, College Park4, Harvard University5, University of Chicago6, University of California, Riverside7, Massachusetts Institute of Technology8, University of Liège9, Vanderbilt University10, Ames Research Center11, George Washington University12, University of Hawaii13, University of California, Santa Cruz14, California Institute of Technology15, University of Warwick16, University of Naples Federico II17, American Association of Variable Star Observers18, University of Cambridge19, University of California, Berkeley20, Tsinghua University21, Southern Connecticut State University22, University of St Andrews23, Australian National University24, Swarthmore College25, Cornell University26, University of Louisville27, University of North Carolina at Chapel Hill28, Tel Aviv University29, Johns Hopkins University30, University of Texas at Austin31, University of Washington32, Boston University33, Space Telescope Science Institute34, Open University35, Bishop's University36, San Diego Mesa College37, Lowell Observatory38, Adler Planetarium39
TL;DR: The transiting exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830) is reported in this article.
Abstract: We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830)—a bright M dwarf at a distance of 10.6 pc. Using the Gaia-measured distance and broadband photometry, we find that the host star is an M3 dwarf. Combined with the TESS transits from three sectors, the corresponding stellar parameters yield planet radii ranging from 0.8 R ⊕ to 1.6 R ⊕. All three planets have short orbital periods, ranging from 2.25 to 7.45 days with the outer pair just wide of a 2:1 period resonance. Diagnostic tests produced by the TESS Data Validation Report and the vetting package DAVE rule out common false-positive sources. These analyses, along with dedicated follow-up and the multiplicity of the system, lend confidence that the observed signals are caused by planets transiting L 98-59 and are not associated with other sources in the field. The L 98-59 system is interesting for a number of reasons: the host star is bright (V = 11.7 mag, K = 7.1 mag) and the planets are prime targets for further follow-up observations including precision radial-velocity mass measurements and future transit spectroscopy with the James Webb Space Telescope; the near-resonant configuration makes the system a laboratory to study planetary system dynamical evolution; and three planets of relatively similar size in the same system present an opportunity to study terrestrial planets where other variables (age, metallicity, etc.) can be held constant. L 98-59 will be observed in four more TESS sectors, which will provide a wealth of information on the three currently known planets and have the potential to reveal additional planets in the system.
81 citations
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TL;DR: In this article, the authors adapted the algorithmic tools developed during the Kepler mission to verify the quality of transit-like signals for use on the K2 mission data and produced a uniformly-vetted catalog of 772 transiting planet candidates from K2 as listed at the NASA Exoplanet archive.
Abstract: We have adapted the algorithmic tools developed during the Kepler mission to vet the quality of transit-like signals for use on the K2 mission data. Using the four sets of publicly-available lightcurves on MAST, we produced a uniformly-vetted catalog of 772 transiting planet candidates from K2 as listed at the NASA Exoplanet archive in the K2 Table of Candidates. Our analysis marks 676 of these as planet candidates and 96 as false positives. All confirmed planets pass our vetting tests. 60 of our false positives are new identifications -- effectively doubling the overall number of astrophysical signals mimicking planetary transits in K2 data. Most of the targets listed as false positives in our catalog either show prominent secondary eclipses, transit depths suggesting a stellar companion instead of a planet, or significant photocenter shifts during transit. We packaged our tools into the open-source, automated vetting pipeline DAVE (Discovery and Vetting of Exoplanets) designed to streamline follow-up efforts by reducing the time and resources wasted observing targets that are likely false positives. DAVE will also be a valuable tool for analyzing planet candidates from NASA's TESS mission, where several guest-investigator programs will provide independent lightcurve sets -- and likely many more from the community. We are currently testing DAVE on recently-released TESS planet candidates and will present our results in a follow-up paper.
31 citations
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TL;DR: The algorithmic tools developed during the Kepler mission are adapted to vet the quality of transit-like signals for use on the K2 mission data, resulting in a uniformly-vetted catalog of 772 transiting planet candidates from K2, which marks 676 as planet candidates and 96 as false positives.
Abstract: We have adapted the algorithmic tools developed during the Kepler mission to vet the quality of transit-like signals for use on the K2 mission data. Using the four sets of publicly available light curves at MAST, we produced a uniformly vetted catalog of 772 transiting planet candidates from K2 as listed at the NASA Exoplanet Archive in the K2 Table of Candidates. Our analysis marks 676 of these as planet candidates and 96 as false positives. All confirmed planets pass our vetting tests. Sixty of our false positives are new identifications, effectively doubling the overall number of astrophysical signals mimicking planetary transits in K2 data. Most of the targets listed as false positives in our catalog show either prominent secondary eclipses, transit depths suggesting a stellar companion instead of a planet, or significant photocenter shifts during transit. We packaged our tools into the open-source, automated vetting pipeline Discovery and Vetting of Exoplanets (DAVE), designed to streamline follow-up efforts by reducing the time and resources wasted observing targets that are likely false positives. DAVE will also be a valuable tool for analyzing planet candidates from NASA's TESS mission, where several guest-investigator programs will provide independent light-curve sets—and likely many more from the community. We are currently testing DAVE on recently released TESS planet candidates and will present our results in a follow-up paper.
29 citations
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TL;DR: In this paper, the authors provide 28 new planet candidates that have been vetted by citizen scientists and expert astronomers, including two sub-Neptune planets and one multi-planet system (EPIC 246042088).
Abstract: We provide 28 new planet candidates that have been vetted by citizen scientists and expert astronomers. This catalog contains 9 likely rocky candidates ($R_{pl} 2.0R_\oplus$). Within this list we find one multi-planet system (EPIC 246042088). These two sub-Neptune ($2.99 \pm 0.02R_\oplus$ and $3.44 \pm 0.02R_\oplus$) planets exist in a near 3:2 orbital resonance. The discovery of this multi-planet system is important in its addition to the list of known multi-planet systems within the K2 catalog, and more broadly in understanding the multiplicity distribution of the exoplanet population (Zink et al. 2019). The candidates on this list are anticipated to generate RV amplitudes of 0.2-18 m/s, many within the range accessible to current facilities.
19 citations
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28 Feb 2019
TL;DR: This work makes available 204,855 statistically significant dips in K2 light curves from campaigns 0–8, 10, and 12–14 and uses the k2phot pipeline to remove the K2 systematics and searched for periodic transits using the TERRA search algorithm.
Abstract: The K2 mission has successfully found ≈1000 new exoplanet candidates.12 Now with an enormous data set (≈400,000 stellar targets) that nearly doubles the source count of Kepler (Huber et al. 2016), data parsing provides a unique time intensive obstacle. The Exoplanet Explorers13 project, part of the Zooniverse platform, allows citizen scientists to help overcome the abundance of transit data (Christiansen et al. 2018). We make available 204,855 statistically significant dips in K2 light curves from campaigns 0–8, 10, and 12–14. We used the k2phot pipeline (Petigura et al. 2018) to remove the K2 systematics and searched for periodic transits using the TERRA search algorithm (Petigura et al. 2013). For training, each participant is shown an example of a real folded exoplanet transit light curve, with the expected model plotted over the data. The volunteer is then instructed to look for dips that provide a similar match to this basic transit model. Each folded light curve presented are assigned a "Yes" or "No" value by the citizen scientist, indicating their belief that the source of the dip is caused by a transiting exoplanet. This simple visual inspection helps create a targeted search of the K2 light curves.
19 citations
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University of Chicago1, Tufts University2, Goddard Space Flight Center3, University of Tokyo4, NASA Exoplanet Science Institute5, California Institute of Technology6, University of the Virgin Islands7, Ames Research Center8, University of North Carolina at Asheville9, Massachusetts Institute of Technology10, University of California, Berkeley11, University of California, Santa Cruz12, University of Oxford13, Moorpark College14, University of Maryland, College Park15
TL;DR: K2-288Bb is the third transiting planet system identified by the Exoplanet Explorers program and its discovery exemplifies the value of citizen science in the era of Kepler, K2, and the Transiting Explanet Survey Satellite as mentioned in this paper.
Abstract: Observations from the Kepler and K2 missions have provided the astronomical community with unprecedented amounts of data to search for transiting exoplanets and other astrophysical phenomena. Here, we present K2-288, a low-mass binary system (M2.0 ± 1.0; M3.0 ± 1.0) hosting a small (R_p = 1.9 R⊕), temperate (T_(eq) = 226 K) planet observed in K2 Campaign 4. The candidate was first identified by citizen scientists using Exoplanet Explorers hosted on the Zooniverse platform. Follow-up observations and detailed analyses validate the planet and indicate that it likely orbits the secondary star on a 31.39-day period. This orbit places K2-288Bb in or near the habitable zone of its low-mass host star. K2-288Bb resides in a system with a unique architecture, as it orbits at >0.1 au from one component in a moderate separation binary (a_(proj) ~ 55 au), and further follow-up may provide insight into its formation and evolution. Additionally, its estimated size straddles the observed gap in the planet radius distribution. Planets of this size occur less frequently and may be in a transient phase of radius evolution. K2-288 is the third transiting planet system identified by the Exoplanet Explorers program and its discovery exemplifies the value of citizen science in the era of Kepler, K2, and the Transiting Exoplanet Survey Satellite.
18 citations
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TL;DR: In this paper, the authors identify a star, EPIC 249706694 (HD 139139), that was observed during K2 Campaign 15 with the Kepler extended mission that appears to exhibit 28 transit-like events over the course of the 87-day observation.
Abstract: We have identified a star, EPIC 249706694 (HD 139139), that was observed during K2 Campaign 15 with the Kepler extended mission that appears to exhibit 28 transit-like events over the course of the 87-day observation. The unusual aspect of these dips, all but two of which have depths of $200 \pm 80$ ppm, is that they exhibit no periodicity, and their arrival times could just as well have been produced by a random number generator. We show that no more than four of the events can be part of a periodic sequence. We have done a number of data quality tests to ascertain that these dips are of astrophysical origin, and while we cannot be absolutely certain that this is so, they have all the hallmarks of astrophysical variability on one of two possible host stars (a likely bound pair) in the photometric aperture. We explore a number of ideas for the origin of these dips, including actual planet transits due to multiple or dust emitting planets, anomalously large TTVs, S- and P-type transits in binary systems, a collection of dust-emitting asteroids, `dipper-star' activity, and short-lived starspots. All transit scenarios that we have been able to conjure up appear to fail, while the intrinsic stellar variability hypothesis would be novel and untested.
17 citations
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University of Chicago1, Tufts University2, Goddard Space Flight Center3, University of Tokyo4, NASA Exoplanet Science Institute5, California Institute of Technology6, University of the Virgin Islands7, Ames Research Center8, University of North Carolina at Asheville9, Massachusetts Institute of Technology10, University of California, Berkeley11, University of California, Santa Cruz12, University of Oxford13, Moorpark College14, University of Maryland, College Park15
TL;DR: K2-288Bb is the third transiting planet system identified by the Exoplanet Explorers program and its discovery exemplifies the value of citizen science in the era of Kepler, K2, and the Transiting Explanet Survey Satellite as mentioned in this paper.
Abstract: Observations from the Kepler and K2 missions have provided the astronomical community with unprecedented amounts of data to search for transiting exoplanets and other astrophysical phenomena. Here, we present K2-288, a low-mass binary system (M2.0 +/- 1.0; M3.0 +/- 1.0) hosting a small (Rp = 1.9 REarth), temperate (Teq = 226 K) planet observed in K2 Campaign 4. The candidate was first identified by citizen scientists using Exoplanet Explorers hosted on the Zooniverse platform. Follow-up observations and detailed analyses validate the planet and indicate that it likely orbits the secondary star on a 31.39-day period. This orbit places K2-288Bb in or near the habitable zone of its low-mass host star. K2-288Bb resides in a system with a unique architecture, as it orbits at >0.1 au from one component in a moderate separation binary (aproj approximately 55 au), and further follow-up may provide insight into its formation and evolution. Additionally, its estimated size straddles the observed gap in the planet radius distribution. Planets of this size occur less frequently and may be in a transient phase of radius evolution. K2-288 is the third transiting planet system identified by the Exoplanet Explorers program and its discovery exemplifies the value of citizen science in the era of Kepler, K2, and the Transiting Exoplanet Survey Satellite.
14 citations
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TL;DR: In this paper, the Causal Pixel Model (CPM) was extended for less-crowded fields, first by using the pixel response function together with accurate astrometric grids, second by combining signals from a few pixels and third by simultaneously fitting for an astrophysical model.
Abstract: In its Campaign 9, K2 observed dense regions toward the Galactic bulge in order to constrain the microlensing parallaxes and probe for free-floating planets. Photometric reduction of the K2 bulge data poses a significant challenge due to a combination of the very high stellar density, large pixels of the Kepler camera, and the pointing drift of the spacecraft. Here we present a new method to extract K2 photometry in dense stellar regions. We extended the Causal Pixel Model developed for less-crowded fields, first by using the pixel response function together with accurate astrometric grids, second by combining signals from a few pixels, and third by simultaneously fitting for an astrophysical model. We tested the method on two microlensing events and a long-period eclipsing binary. The extracted K2 photometry is an order of magnitude more precise than the photometry from other method.
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TL;DR: In this article, the authors demonstrate the power of new, fast open-source community tools (e.g., lightkurve, starry, celerite, exoplanet), and discuss four high signal-to-noise ratio (S/N) exoplanets that showcase specific challenges present in planet detection.
Abstract: The Kepler, K2, and Transiting Exoplanet Survey Satellite (TESS) missions have provided a wealth of confirmed exoplanets, benefiting from a huge effort from the planet-hunting and follow-up community. With careful systematics mitigation, these missions provide precise photometric time series, which enable detection of transiting exoplanet signals. However, exoplanet hunting can be confounded by several factors, including instrumental noise, search biases, and host star variability. In this Letter, we discuss strategies to overcome these challenges using newly emerging techniques and tools. We demonstrate the power of new, fast open-source community tools (e.g., lightkurve, starry, celerite, exoplanet), and discuss four high signal-to-noise ratio (S/N) exoplanets that showcase specific challenges present in planet detection: K2-43c, K2-168c, K2-198c, and K2-198d. These planets have been undetected in several large K2 planet searches, despite having transit signals with S/N > 10. Two of the planets discussed here are new discoveries. In this work we confirm all four as true planets. Alongside these planet systems, we discuss three key challenges in finding small transiting exoplanets. The aim of this Letter is to help new researchers understand where planet detection efficiency gains can be made, and to encourage the continued use of K2 archive data. The considerations presented in this Letter are equally applicable to Kepler, K2, and TESS, and the tools discussed here are available for the community to apply to improve exoplanet discovery and fitting.
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28 Jan 2019•
Space Telescope Science Institute1, University of Rome Tor Vergata2, Ames Research Center3, Denver Museum of Nature and Science4, Princeton University5, University of Rochester6, California Institute of Technology7, Planetary Science Institute8, Space Sciences Laboratory9, Eclipse Internet10, Search for extraterrestrial intelligence11, Université de Montréal12
TL;DR: The small size of the SETI workforce is a major problem for NASA and the search for life elsewhere in the universe and the Astro2020 Decadal should address this issue by making nurturing the field an explicit priority for the next decade.
Abstract: The small size of the SETI workforce is a major problem for NASA and the search for life elsewhere in the universe. The Astro2020 Decadal should address this issue by making nurturing the field an explicit priority for the next decade.
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TL;DR: In this article, the authors highlight changes that will enable a sustainable software sharing system for astronomy and astrophysics in the next decade, which is critical to astronomical research and has long-term impacts on scientific outcomes.
Abstract: Software is critical to astronomical research. Sharing and sustaining astronomical software has long-term impacts on scientific outcomes. However, support for this has been uneven, creating significant risks. Thus, we highlight changes that will enable a sustainable software sharing system for astronomy and astrophysics in the next decade.
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TL;DR: The power of new, fast open-source community tools is demonstrated, and four high signal-to-noise ratio exoplanets that showcase specific challenges present in planet detection are discussed that are confirmed as true planets.
Abstract: The Kepler, K2, and Transiting Exoplanet Survey Satellite (TESS) missions have provided a wealth of confirmed exoplanets, benefiting from a huge effort from the planet-hunting and follow-up community. With careful systematics mitigation, these missions provide precise photometric time series, which enable detection of transiting exoplanet signals. However, exoplanet hunting can be confounded by several factors, including instrumental noise, search biases, and host star variability. In this Letter, we discuss strategies to overcome these challenges using newly emerging techniques and tools. We demonstrate the power of new, fast open-source community tools (e.g., lightkurve, starry, celerite, exoplanet), and discuss four high signal-to-noise ratio (S/N) exoplanets that showcase specific challenges present in planet detection: K2-43c, K2-168c, K2-198c, and K2-198d. These planets have been undetected in several large K2 planet searches, despite having transit signals with S/N > 10. Two of the planets discussed here are new discoveries. In this work we confirm all four as true planets. Alongside these planet systems, we discuss three key challenges in finding small transiting exoplanets. The aim of this Letter is to help new researchers understand where planet detection efficiency gains can be made, and to encourage the continued use of K2 archive data. The considerations presented in this Letter are equally applicable to Kepler, K2, and TESS, and the tools discussed here are available for the community to apply to improve exoplanet discovery and fitting.
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California Institute of Technology1, Arizona State University2, Harvard University3, Steward Health Care System4, Carnegie Institution for Science5, Florida Gulf Coast University6, Search for extraterrestrial intelligence7, Ames Research Center8, Goddard Space Flight Center9, Johns Hopkins University Applied Physics Laboratory10, Lowell Observatory11, University of Michigan12, University of Western Ontario13, George Mason University14, W.M. Keck Observatory15, Massachusetts Institute of Technology16, Jet Propulsion Laboratory17, Austin Peay State University18, Çağ University19, Rochester Institute of Technology20
TL;DR: It is suggested that NASA decouples science and technology for SmallSats by creating a technology-based SmallSat AO, modeled after the Earth Sciences InVEST call, which would help reduce the new technology risk for science missions of any size.
Abstract: The commercial SmallSat industry is booming and has developed numerous low-cost, capable satellite buses. SmallSats can be used as vehicles for technology development or to host science missions. Missions hosted on SmallSats can answer specific science questions that are difficult or impossible to answer with larger facilities, can be developed relatively quickly, serve to train engineering and scientists, and provide access to space for small institutions. SmallSats complement larger Astrophysics missions and allow the broader community to test new ideas at the bottom of the market, creating new capabilities which find their way to larger missions. Currently, NASA Astrophysics does not provide flight opportunities that would allow technology maturation of instrument systems or concepts of operations. Without flight opportunities to mature technologies, missions hosted on SmallSats are likely to be considered high risk, and face long odds being selected for implementation. Our primary suggestion is that NASA decouples science and technology for SmallSats by creating a technology-based SmallSat AO, modeled after the Earth Sciences InVEST call. Such AO would help reduce the new technology risk for science missions of any size. We also suggest that NASA provides additional science-driven SmallSat opportunities at the ~$12M funding level, provides access to new launchers free of charge to proposers, and re-structures the solicitation AOs so that SmallSats do not compete with other mission classes such as balloons.