The discovery is of special interest because it represents a rare case in which a research team was able to make an independent age determination of the planet system by studying the system’s faint red dwarf companion star. The discovery opens a new gateway to learning about the dynamics and evolution of many other planetary systems that also contain close-in hot-Jupiter type planets.
HD189733b, the Hot Jupiter exoplanet, orbits an orange (dwarf K) star HD18973A in the constellation Vulpecula (the Fox). It orbits at only three percent of the distance of the Earth from the Sun: i.e. ~0.03 AU) with an orbital period of only 2.2 days (for comparison the Earth takes 365 days to orbit our Sun). The host star is about 63 light-years away and has a mass and diameter about ~80 percent that of our Sun. This star, invigorated by its hot Jupiter planetary companion, appears to have been spun up (rotating ~ >2x faster than our Sun – having a ~12-day rotation period) and is gaining angular momentum from magnetic and tidal interactions with its close-in Jupiter-size planet. The star, however, is being spun-up at the expense of the planet’s orbital angular energy.
The loss in the planet’s orbital momentum in the past may explain why it (and other similar planetary systems) orbit so close to their host stars. While the planet is spiraling in toward the star, and is most likely doomed, there is a possibility that the interacting magnetic fields of the star and planet could create a tidal-magnetically locked orbit–rotation that might allow the planet to survive. The most likely scenario, however, is that the planet will draw closer to the star and its atmosphere will be eroded away by the star’s intense radiation and strong winds. The planet will ultimately be ripped apart by the star’s gravity if it survives the star’s radiation and winds.
HD 189733 Ab is a relatively rare eclipsing planetary system that was discovered in 2005 (by Buchy et al.) and has attracted much attention in astronomical circles because it hosts a transiting Hot Jupiter exoplanet. The system is relatively bright (e.g. can be seen with binoculars). The eclipses by the planet permit substantial information to be gained from observing the system inside and outside the planetary eclipses. For example, spectroscopic studies by other teams (e.g. G. Tinnetti et al.) reveal that its hot atmosphere contains water vapor, carbon dioxide, sodium, and, interestingly, organic molecules of methane and particulate haze.
The Villanova team, which includes undergraduates Thomas Santapaga and Ronald Ballouz, found that this system is about over five billion years old and that the Jupiter-size planet has been estimated to be very hot at ~1,500 degrees Fahrenheit by other researchers. HD189733b has one of the shortest known orbital periods of only P = 2.22 days and is only 0.031AU from its host star (i.e. only ~8.75x the radius of the host star).
(A scale model of the system is provided.) The exoplanet system includes a cool red dwarf companion star (HD 189733B). This faint companion star is located at ~12” distance to the K-dwarf. At the distance of HD 189733 this corresponds to a separation of ~220 AU/ For comparison this 220x the distance of the Earth from the Sun / or over 5.5x further than the distance of Pluto from the Sun.) The presence of this red dwarf star makes a reliable age estimate of the binary system possible via activity-age relations developed at Villanova.
“Planetary systems like HD 189733 with short period, “hot-Jupiter” planets are very common – over a hundred have been discovered so far,” Guinan noted. He continued, “HD 189733 and dozens of other planetary systems like it, many of which were recently discovered by NASA’s Kepler mission, may also be undergoing the same process of strong magnetic interactions between their close-in large planets and their host stars.”
“The big clue that is different here is that we know the age of HD 189733 from the study of its coeval faint companion star.” This discovery should help in our endeavors to try to better understand the dynamics of other planetary systems like HD 189733, he added.”
Of the over 500 exoplanets that have been discovered to date, HD 189733 is the only one of a handful whose age and physical properties have been well determined.
“This study may help explain how and why hot Jupiters form and evolve. It may help explain this whole class of planets,” Guinan remarked.
In conducting this study the research team, which includes Villanovans Thomas Santapaga, Ronald L. Ballouz, Scott E. Engle, Laurence E. DeWarf, along with Styliani (Stella) Kafka from the Carnegie Institute in Washington, D.C.’s Department of Terrestrial Magnetism, observed the exoplanet system using the Clay Telescope at the Carnegie Institution of Washington’s Las Campanas Observatory in Chile. Observations of the eclipse timings of HD 189733 continue at Villanova using the Four College Automatic Photoelectric Telescope (FCAPT) located in southern Arizona. The eclipse timings made with this telescope over time could provide evidence that the orbital period of the system is indeed decreasing.
The research project is funded through The National Science Foundation‘s Research at Undergraduate Institutions and grants from NASA.
Guinan’s Jan. 10 presentation of the team’s findings at the 217th AAS Meeting are from a paper titled, “Some Like It Hot” – Evidence for the Shrinking Orbit of the 2.2-day Transiting Hot Jupiter Exoplanet HD 189733b – Evidence of Transfer of Planet Orbital Momentum to its Host Star” (AAS 217th Meeting Abstract 343.12, P. 566).
“One of the most amazing results of our team’s research is that a planet-size body that is only 1/1000x times the mass of the host star can make such a large impact by magnetically interacting with its host star to the extent that it causes the star to spin up, activating a strong magnetic dynamo of the star that produces the observed strong X-ray coronal emissions, large starspots and other phenomena,” Guinan concluded.
Kathleen Scavello | Newswise Science News
From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison
Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News