Observing Exoplanets: Recording, reducing, and analyzing ground-based data PTYS 195A Rob Zellem PhD Candidate Lunar & Planetary Laboratory University of Arizona

About me! I am a giant nerd – I love Star Wars! I am a Planetary Astronomer – I am trying to find alien life Grew up in Nashville, TN – Went to grade school and high school there Went to college at Villanova University – Degree in Astronomy and Astrophysics MSc in Space Science at University College London PhD candidate at LPL – Structure and composition of exoplanets – Graduating at the latest this May

Course Website ml Will post lectures and assigned reading Grades will be on D2L – Assuming I can figure it out….

Office Hours Space Sciences 247 By appointment (drop-ins okay if not busy)

Course Objectives Exoplanetary research indicates the existence of planets, a majority of which are completely unlike those in our Solar System. Of the more than 1055 transiting exoplanets discovered to date, over 105 are giant planets, known as “hot Jupiters”, that have near-Jupiter masses and orbit close to their host stars. Due to their large planet-to-star contrast and being hosted by bright stars, these exoplanets are accessible with the University of Arizona’s 61” Kuiper telescope. Here students will record their own data on the 61”. We will learn how to reduce and analyze data from this platform. This class will culminate in a small group presentation on a specific exoplanet, potentially for inclusion in a published paper and Fall 2016 AAS poster presentation. Students will also develop presentation, critical thinking, and critiquing skills.

Class Format The course will be conducted as a seminar, with a particular focus at each meeting. Students are expected to have read the assigned material in advance and be ready to participate in the discussion. Two students will be assigned to lead each discussion with a short presentation on the required reading at the beginning of each class. Weekly reading will typically consist of about one published, peer- reviewed paper. Throughout the semester we will reduce a common dataset. In the middle of the semester, we break down into smaller groups, which each group assigned a specific target. This group will reduce this target and present their results and previously-published data in an 8 minute presentation at the end of the semester.

Textbook NONE! YAY! Published papers available when you are on UofA’s network

Grades 10% for being at the telescope for one observing run 10% weekly presentation 10% weekly quizzes 30% class-wide data reduction project 40% final project (data reduction results 50%) and PowerPoint presentation (50%)

Telescope Signup Sheet

Weekly Presentations 2 students will give a short (8 minute) presentation on the weekly assigned reading and help facilitate a discussion about the methods and results. Students will be graded with the following rubric with a 0 for not meeting the requirement and 2 for meeting the requirement: Read the paper Addressed major paper concepts Explained major concepts clearly and concisely Facilitated discussion with peers and/or answered questions adequately Ask questions in other students’ presentations (when not presenting) BONUS (+1): Found a critique about the paper, only available to presenting students

Weekly Quizzes At the beginning of each class, there will be a short quiz with questions on the previous class or the reading due for the present class. The aim for the daily quiz is to reinforce major class concepts and to provide the instructor with a proxy attendance grade. The lowest 2 quiz grades will be treated as extra credit.

POP QUIZ TIME!!!

Extra Credit The lowest 2 quiz grades will be treated as extra credit, to be added to the “Quiz” portion of the final grade calculation. In addition, there will be opportunities to go to public talks throughout the semester. Each student will be expected to take notes on the topic and get the signature of the instructor or the speaker for credit. Each opportunity will be treated as 1 additional point applied to their final numerical grade.

Academic Integrity It is strongly recommended that all students read the University of Arizona’s Code of Academic Integrity. All students in this course are expected to abide by this code. We will operate with the “3 strike method” for academic integrity issues: 1 st offense will result in a 0 on the assignment in question, 2 nd offense will result in a loss in a letter grade for the class (e.g., a student’s grade will be reduced from an “A” to a “B”), and 3 rd offense will result in a course failure. ALL offenses will be reported to the University according to their Academic Integrity policy.

Planetary Transit Technique Measures dimming of star light as planet passes in front of (or behind) the star Star-light dims less than 1% Like looking for a firefly next to a lighthouse Gives us the size (radius)

Planetary Transit Technique Disadvantages: a) Bias towards large planets and in short period orbits b) False detections due to stellar variability c) Planet’s orbit must be seen edge-on from the observer point of view (so the planet passes in front of the star) Advantages: a) Relatively cheap b) Can determine the size of the planet

Kepler Mission Launched in 2009 Mission objective: to discover Earth- like planets orbiting other stars As of February 2014, 961 confirmed planets – 2903 unconfirmed planet candidates NASA

Exoplanet Atmospheres Transits allow the study of exoplanet atmospheres – Can study how light varies at different wavelengths – tells us about atmospheric structure and composition

Rob’s Thesis Observe transits of HD b – One of the two brightest exoplanets – Hot Jupiter M = M jupiter R = 1.38 R Jupiter AU away from its host star – 25 times closer to its star than the Earth is to the Sun – 9.5 times closer to its star than Mercury is to the Sun day orbital period – ~150 light-years away

UofA’s 61” Kuiper Telescope

Exoplanet Atmospheres Transits allow the study of gas giant atmospheres Griffith et al. 2014

Transit What is it measuring?

Transit The atmosphere + the planet’s disk

Transit The atmosphere + the planet’s optically-thick disk

Transit The atmosphere + the planet’s optically-thick disk

Transit Amount of atmospheric absorption will change with wavelength

Transit Amount of atmospheric absorption will change with wavelength Beer’s Law

Transit So a planet’s radius will change with wavelength due to absorption by different molecules in its atmosphere

So…. If we measure the transit of an exoplanet at different wavelengths… – We can measure how its radius varies with wavelength – Indicates its atmospheric structure and content Atmospheric structure = how temperature varies with altitude Atmospheric content = what molecules are present

Example! Detection of H 2 scattering Zellem et al. (in prep.)

Example! Detection of H 2 scattering

Another Example! Detection of water, methane, and carbon dioxide in a hot Jupiter’s atmosphere Swain et al. (2009)

Measuring radii at the 61” Planet has same signature in the infrared (IR) despite differing atmospheric contents optical Signal very different in the optical Benneke & Seager (2013)

Why are the IR signatures the same? In the IR, a small planet with a thick atmosphere can block as much light as a large planet with a small atmosphere – Hot Jupiter atmospheres are opaque in the IR

Why are the IR signatures the same? In the IR, a small planet with a thick atmosphere can block as much light as a large planet with a small atmosphere – Hot Jupiter atmospheres are opaque in the IR =

However, not the same in the visible In the visible, the planet’s atmosphere is now transparent, so a small planet will look different than a large one

However, not the same in the visible In the visible, the planet’s atmosphere is now transparent, so a small planet will look different than a large one ≠

Rob does a spectroscopy trick IT’S AN ILLUSION, MICHAEL.

Measuring radii at the 61” Planet has same signature in the infrared (IR) despite differing atmospheric contents optical Signal very different in the optical Benneke & Seager (2013)

Looking for New Planets

Transit Timing Variations (TTVs)

Looking for Exomoons

Measuring Exoplanetary Magnetic Fields

In the UVIn the B

Hubble Magnetic Field Detection Fossati et al. (2010)