Exoplanets Saturday Physics for Everyone Jon Thaler October 27, 2012 Credit: NASA/Kepler Mission/Dana Berry.

Slides:



Advertisements
Similar presentations
© 2005 Pearson Education Inc., publishing as Addison-Wesley Extrasolar Planets Since our Sun has a family of planets, shouldnt other stars have them as.
Advertisements

Destination: A Planet like Earth Caty Pilachowski IU Astronomy Mini-University, June 2011 Caty Pilachowski Mini-University 2011.
Important Stuff (Section 3) The Final Exam is Monday, December 19, 1:30 pm – 3:30 pm The Final Exam will be given in Physics 150 Physics 150 (seats over.
Chapter 13 Other Planetary Systems The New Science of Distant Worlds.
A Search for Habitable Planets 1 NASA’s first mission to detect Earth-size planets orbiting in the habitable zone of sun-like stars. Launched March 6,
Tim Healy Tony Perry Planet Survey Mission. Introduction Finding Planets Pulsar Timing Astrometry Polarimetry Direct Imaging Transit Method Radial Velocity.
Other Planetary Systems. Detecting Extrasolar Planets  Extrasolar planets are planets orbiting other stars.  We usually detect these planets by the.
Extra-Solar Planets Astronomy 311 Professor Lee Carkner Lecture 24.
Other Planetary Systems (Chapter 13) Extrasolar Planets
© 2010 Pearson Education, Inc. Chapter 13 Other Planetary Systems: The New Science of Distant Worlds.
Habitable Planets Astronomy 315 Professor Lee Carkner Special Topic.
All About Exoplanets Dimitar D. Sasselov Harvard-Smithsonian Center for Astrophysics.
Extra-Solar Planets Astronomy 311 Professor Lee Carkner Lecture 24.
The Next 25(?) Years Future Missions to Search for Extra-solar Planets and Life.
First direct image of extrasolar planets billion miles.
Extra-Solar Planets Astronomy 311 Professor Lee Carkner Lecture 24.
Copyright © 2012 Pearson Education, Inc. Extrasolar Planetary Systems.
Astronomy190 - Topics in Astronomy Astronomy and Astrobiology Lecture 4 : Astronomy Basics Ty Robinson.
Extra-Solar Planets Astronomy 311 Professor Lee Carkner Lecture 24.
3677 Life in the Universe: Extra-solar planets
Today’s APODAPOD  Begin Chapter 8 on Monday– Terrestrial Planets  Hand in homework today  Quiz on Oncourse The Sun Today A100 – Ch. 7 Extra-Solar Planets.
Extrasolar Planets extrasolar = outside of (external to) our solar system.
6.5 Other Planetary Systems Our goals for learning: How do we detect planets around other stars? How do extrasolar planets compare with those in our own.
1 Habitability Outside the Solar System A discussion of Bennett & Shostak Chapter 11 HNRT 228 Dr. H. Geller Fall 2012.
Lecture 34. Extrasolar Planets. reading: Chapter 9.
Astro 101 Slide Set: Kepler’s Exoplanet Discoveries Exceed 1,000 0 Topic: Exoplanets Concepts: Transit Detection, Exoplanet Statistics Mission: Kepler.
AST 111 Exoplanets I.
Extrasolar planets. Detection methods 1.Pulsar timing 2.Astrometric wobble 3.Radial velocities 4.Gravitational lensing 5.Transits 6.Dust disks 7.Direct.
Extra Solar Planets Just some introductory materials. A very fast moving field. My favorite website:
Extra-Solar Planets Astronomy 311 Professor Lee Carkner Lecture 24.
Blayne Chang Aaron Fujioka Pd. 3. Exoplanets  “Extra-solar”  A planet that orbits a star other than our sun  Therefore is beyond the solar system with.
Lecture Outline Chapter 10: Other Planetary Systems: The New Science of Distant Worlds © 2015 Pearson Education, Inc.
The Search for Extrasolar Planets Since it appears the conditions for planet formation are common, we’d like to know how many solar systems there are,
Worlds Unnumbered Lecture Twenty-Nine, Apr. 14, 2003.
Worlds around Distant Suns Mini University June 16, 2003 Among the most significant discoveries of the 20th Century.
Copyright © 2012 Pearson Education, Inc. How do we detect planets around other stars?
Search for Extra-Solar Planets. Background 1995 first discovered evidence that other stars have planets first discovered evidence that other stars.
Extrasolar Planets The Search For Ever since humans first gazed into the night sky, the question of whether we are alone in the universe has remained unanswered.
Extra-Solar Planetary Systems. Current Planet Count: 331 Stars with Planets: 282 Earthlike Planets: 0 Four of the five planets that orbit 55 Cancri.
The Search for Extra-Solar Planets Dr Martin Hendry Dept of Physics and Astronomy.
Extrasolar Planets Exo planets are planets outside the Solar System. They orbit another star. 861 confirmed…18,000 identified, but likely billions exist.
1. Exoplanet detection (500+) 2 Gravitational attraction between a stellar mass (sun) and planets (bigger the better, why?) makes sun’s position wobble.
Extrasolar planets. Detection methods 1.Pulsar Timing Pulsars are rapidly rotating neutron stars, with extremely regular periods Anomalies in these periods.
Homework 8 Due: Monday, Nov. 28, 9:00 pm, Exam 2: Weds., Nov. 30.
EXAM II COMING UP Monday Oct 19 th (a week from this coming Monday!) HW5 due a week from today.
Lecture 34 ExoPlanets Astronomy 1143 – Spring 2014.
The Search for Life in the Universe. Criteria Defining Life 1.Made up of one or more cells 2.Organized 3.Grows & develops 4.Reproduces 5.Responds to stimuli.
PHYS 1621 Planet Formation contracting gas/dust cloud  forms stars  swirling disk of material (H, He, C, O, heavier elements, molecules, “dust”)  form.
NASA’s Kepler and K2 Missions:
2003 UB313: The 10th Planet?. Extra-Solar or Exoplanets Planets around stars other than the Sun Difficult to observe Hundreds discovered (> 2000 so far)
2003 UB313: The 10th Planet?. Extra-Solar or Exoplanets Planets around stars other than the Sun Difficult to observe Hundreds discovered (> 2000 so far)
The Search for Another Earth Exoplanets and the Kepler Spacecraft.
Nick Weber ZONES OF HABITABILITY AROUND NORMAL STARS.
Lecture Outline Chapter 10: Other Planetary Systems: The New Science of Distant Worlds.
Lecture Outlines Astronomy Today 8th Edition Chaisson/McMillan © 2014 Pearson Education, Inc. Chapter 15.
Extrasolar planets - exoplanets Planets have been discovered orbiting other stars. The list of confirmed exoplanets has over 1900.list Evidence comes from.
Exoplanets: Direct Search Methods 31 March 2016 © 2014 Pearson Education, Inc.
Searching for Alien Worlds. Methods of Searching for Alien Planets Pulsar Timing Astrometry Radial Velocity Transits Lensing Imaging.
Chapter 10: Other Planetary Systems: The New Science of Distant Worlds
Exoplanets: Indirect Search Methods
Kepler Mission Alex Kang Exoplanet History Scientific Goals
Chapter 13 Other Planetary Systems
Exoplanets: The New Science of Distant Worlds
Exoplanets EXOPLANETS Talk prepared by: Santanu Mohapatra(14PH20032)
3677 Life in the Universe: Extra-solar planets
PHYS 2070 Tetyana Dyachyshyn
Goal: To learn about the Kepler Mission and the Transit Method
Extrasolar Planets.
What is an Exoplanet? Why is their search important?
Planets Tuesday, March 4.
Presentation transcript:

Exoplanets Saturday Physics for Everyone Jon Thaler October 27, 2012 Credit: NASA/Kepler Mission/Dana Berry

Jon Thaler Exoplanets 2 Outline What is an exoplanet? Why are they interesting? How can we find them? Exolife ?? The future...

Jon Thaler Exoplanets 3 What is an Exoplanet? Most of the objects that we see are stars. Exoplanets are things that orbit stars. How do we know that we are not seeing binary stars, which are quite common? The minimum stellar mass is about 0.075*M S (= 75 M J ). Otherwise there is no fusion at the core.Planets don’t emit light. Low mass and no light are both used to identify planets. T core Gravitational pressure heats the core. T core ~ 15 million degrees for fusion.

Jon Thaler Exoplanets 4 Why Are They Interesting? Stars (including binaries) and planets are thought to form from a primordial blob of gas, but the details are controversial. I won’t discuss this topic. Planets come in two types: °Gas giants(e.g., Jupiter) °Rocks(e.g., Earth) We’d like to know if there are other Earth-like planets that could support life: “Goldilocks” planets. Not too hot and not too cold The disk shape is a result of the rotation. The green regions are the “habitable zones”.

Jon Thaler Exoplanets 5 How Can We Find Exoplanets? There are two primary methods: The star wobbles as the planet orbits it. The star becomes (slightly) dimmer if the planet passes in front of it (“transits” the star). Ideally, we’d like to observe a planet both ways.

Jon Thaler Exoplanets 6 The Wobble method When objects are orbiting each other, neither is stationary. The center of mass remains fixed, and each object moves around it. The ratio of speeds equals the ratio of masses. This means that we can measure the mass of the planet by measuring the speed of the star. The Sun is much heavier than the planets: M J /M S = and M E /M S = (3×10 -6 ) This means that the Sun’s speed is quite small: 12.5 m/s due to Jupiter and 8.4 cm/s due to the Earth. These speeds can be measured using the Doppler effect. Radial velocity Star & planet

Jon Thaler Exoplanets 7 The Doppler Effect You’ve all heard the change of pitch as a car or ambulance passes by. The size of the effect depends on the ratio of the car’s speed to the speed of sound. In this video, the pitch drops from about 475 Hz to 425 Hz (B to G), indicating that the car is going about 19 m/s (43 mph). Light is a wave, just like sound, so we can use the optical Doppler effect to measure speeds. The difficulty is that the speed of light is huge (300,000,000 m/s) and the stars are not moving very fast (1 m/s, or so). The frequency needs to be measured to an accuracy of 1/300,000,000 !! (three parts per billion) Car horn doppler

Jon Thaler Exoplanets 8 Some Doppler Data Fortunately, optical techniques are capable of exquisite accuracy. Let’s look at some data. Note the scatter of the data points. The measurement accuracy is about ±2 m/s. Measurement accuracy limits our ability to observe small effects. This is a “Jupiter” (M ~ 0.96 M J ) orbiting a “Sol” (M = 0.88 M S ). The orbital period is 9 years (Jupiter’s is 12), because the orbit is a bit smaller (4.2 AU instead of 5.2). This is how astronomers 60 light-years away could discover Jupiter. Radial velocity

Jon Thaler Exoplanets 9 More Doppler Data Most planet observations involve much shorter orbital periods: Note that the plot has marginal significance. Kepler 10b was not discovered by the wobble method. This data served only to confirm the discovery. This is an “Earth” (M ~ 4.6 M E ) orbiting a “Sol” (M = 0.90 M S ). The period is 0.84 days (20 hours), because the orbit is only AU). It is called Kepler 10b (more about it later). It’s too hot (1800 K) to be habitable.

Jon Thaler Exoplanets 10 Can We Discover a Goldilocks? Here’s a plot of planets discovered by the wobble method. Our solar system is labeled in blue. Only Jupiter could be discovered with the wobble method, unless measurement accuracy improves. Speed Earth Jupiter The Sun moves 8.4 cm/s due to Earth’s orbit. 1 m/s resolution makes it undetectable. Kepler 10b

Jon Thaler Exoplanets 11 Planetary Transits When a planet passes in front of a star, the star appears dimmer. The fraction depends on the ratio of the areas: Radius of Sun:7.0×10 5 kmDimming: Radius of Jupiter:7.1×10 4 km0.01 (i.e., 1%) Radius of Earth:6.4×10 3 km (i.e., 0.01%) Venus and Mercury transit the Sun, but the dimming is miniscule. Here’s an interesting video: 1882 transit 1882 transit !!

Jon Thaler Exoplanets 12 Planetary Transits (2) Here’s what one expects to observe: Jupiter: brightness accuracy required Earth: brightness accuracy required accuracy is achievable directly, but can only be achieved by averaging many measurements (requires orbits with short periods). Transit Simulator

Jon Thaler Exoplanets 13 NASA’s Kepler Mission “A search for habitable planets” It uses an 85 Megapixel camera to monitor more than 100,000 stars for transiting planets. Launched in 2009, it is in solar (not Earth) orbit.

Jon Thaler Exoplanets 14 Kepler has found 2321 planet candidates and 2165 eclipsing binary stars. Here’s the discovery (in 2011) of Kepler 10b, the first rocky planet: Some Kepler Data This is probably a “Neptune”. Orbital period is 45 days. Radius is 2.2 R E. This is Kepler 10b, a rocky planet. However, it’s too hot (1800 K) for Goldilocks. Orbital period is 20 hours! Orbital radius ~ AU. Light curve when the planet is in front of the starLight curve when the planet is behind the star

Jon Thaler Exoplanets 15 Eclipsing binary stars don’t look the same as transiting planets, because both objects emit light. Binary Stars Look Different Eclipsing binary

Jon Thaler Exoplanets 16 The Search for Exolife Suppose we find an Earth-like planet in the habitable zone. How can we tell if it has life? We need to know more about the planet than its mass. We cannot yet image exoplanets, but it is just now becoming possible to learn something about their chemical composition. One can determine the chemical composition of a gas by measuring the absorption of light that passes through it. So, this property of a transiting exoplanet’s atmosphere can, in principle, be measured.

Jon Thaler Exoplanets 17 Absorption Spectra Here are the absorption spectra of various gases. When a planet passes in front of a star, some of the wavelengths emitted by the star are absorbed by the planet’s atmosphere. For example, carbon monoxide absorbs near 5 microns Wavelength (microns) CO CH 4 N2ON2O CO 2 HDO O3O3 H2OH2O Here are the absorption spectra of three planetary atmospheres. This is real data!! Which planet has life?

Jon Thaler Exoplanets 18 Exolife Water and, especially, oxygen (in this case ozone) are smoking gun indicators of our kind of life. Oxygen is much too reactive to remain in the atmosphere without plant life to replenish it. This is a very difficult measurement to make in an exoplanet, especially a small, Earthlike one.

Jon Thaler Exoplanets 19 A Proof of the Principle This year, astronomers used the Very Large Telescope (VLT, a set of four 8 m telescopes in Chile) to detect carbon monoxide in the atmosphere of a “Super Jupiter” that orbits Tau Bootis (a visible star). Gas giants have lots of atmosphere, so this is an “easy” measurement. Unfortunately, the data analysis is quite complex and doesn’t lend itself to a nice graphic. Trust me! The star: Mass:1.3 M S Distance:51 l.y. The planet: Mass:4.1 M J Orbit:0.05 AU

Jon Thaler Exoplanets 20 The Future... The European Space Agency (ESA) considered a set of satellites (the Darwin mission) to search for life on Earthlike exoplanets, but abandoned it as unfeasible at this time. NASA considered, and abandoned, a similar project (the Terrestrial Planet Finder). Perhaps in years... Scientific and technical progress are intertwined, but that’s another talk.