My work in Astronomy

Hi, I’m
STEFANO MESCHIARI
and I study
EXOPLANETS
Civitas Learning — 11/11/2015
UT AUSTIN/MCDONALD OBSERVATORY

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My work: overview
Systemic
• A package to analyze exoplanetary data
• A virtual lab for teachers & students
SAVE/Point
• A pilot platform for education
• 4 games and apps ready to play
• Discovering new exoplanets
• Understand how they form
• Creating apps for education & outreach
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-5 0 5 10
Time [JD]
RV, Planet b [m/s]
Q01 KECK APF
0 1 2 3 4 5 6 7
-10 -5 0 5
Time [JD]
RV, Planet c [m/s]
Q01 KECK APF
-10 -5 0 5 10
RV, Planet f [m/s]
Q01 KECK APF
0 20 40 60 80
-10 -5 0 5 10
Time [JD]
RV, Planet g [m/s]
Q01 KECK APF
0 500 1000 1500 2000
-10 -5 0 5 10
Time [JD]
RV, Planet h [m/s]
Q01 KECK APF
-5 0 5
Residuals [m/s]

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What are exoplanets?
SINCE 1995, WE NOW KNOW APPROXIMATELY 5,000 PLANET CANDIDATES!
51 Peg b Gliese 581d Kepler 16 ABb Earth twin Jupiter analog
with exomoon

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What are exoplanets?
SINCE 1995, WE NOW KNOW APPROXIMATELY 5,000 PLANET CANDIDATES!
51 Peg b Gliese 581d Kepler 16 ABb Earth twin Jupiter analog
with exomoon
Exoplanetary systems don’t look like the Solar
System. Why?
PROBLEM:

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10-1
100
101
102
103
100 101 102 103 104 105
Period [days]
Mass [MEarth
]
Discovery method
RV
Transit
Imaging
Timing
Microlensing
Are we unique ❄ snowflakes❄?
COPERNICAN MEDIOCRITY PRINCIPLE: PROBABLY NOT. MASSIVE SELECTION EFFECT
Earth
Jupiter
Saturn
Uranus
Harder to
detect

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Are we unique ❄ snowflakes❄?
COPERNICAN MEDIOCRITY PRINCIPLE: PROBABLY NOT, BUT…
0.125 AU
HD 219134
Mercury
Earth
Vogt, Burt, Meschiari et al., 2015

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Answering the why
(1) FIND MORE EXOPLANETS!
Automated Planet
Finder (APF)
Keck
Discovering new exoplanets through data
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-5 0 5 10
Time [JD]
RV, Planet b [m/s]
Q01 KECK APF
0 1 2 3 4 5 6 7
-10 -5 0 5
Time [JD]
RV, Planet c [m/s]
Q01 KECK APF
0 5 10 15 20
-10 -5 0 5 10
Time [JD]
RV, Planet f [m/s]
Q01 KECK APF
0 5 10
net d [m/s]
Q01 KECK APF
0 20 40 60 80
-10 -5 0 5 10
Time [JD]
RV, Planet g [m/s]
Q01 KECK APF
0 500 1000 1500 2000
-10 -5 0 5 10
Time [JD]
RV, Planet h [m/s]
Q01 KECK APF
2451000 2453000 2455000 2457000
-5 0 5
Time [JD]
Residuals [m/s]
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-5 0 5 10
Time [JD]
RV, Planet b [m/s]
Q01 KECK APF
0 1 2 3 4 5 6 7
-10 -5 0 5
Time [JD]
RV, Planet c [m/s]
Q01 KECK APF
0 5 10 15 20
-10 -5 0 5 10
Time [JD]
RV, Planet f [m/s]
Q01 KECK APF
0 10 20 30 40
-10 -5 0 5 10
Time [JD]
RV, Planet d [m/s]
Q01 KECK APF
0 20 40 60 80
-10 -5 0 5 10
Time [JD]
RV, Planet g [m/s]
Q01 KECK APF
0 500 1000 1500 2000
-10 -5 0 5 10
Time [JD]
RV, Planet h [m/s]
Q01 KECK APF
2451000 2453000 2455000 2457000
-5 0 5
Time [JD]
Residuals [m/s]
Meschiari et al., 2009, 2010, 2011; Vogt, Burt, Meschiari+15; Rowan & Meschiari et al., Meschiari et al. 2015
submitted; + 10 more papers

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Answering the why
(2) HOW ROBUST IS PLANET FORMATION?
Understanding how planets form in extreme conditions
Meschiari et al., 2008, 2012, 2012, 2014; Meschiari et al., 2015, in prep

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Answering the why
(3) EMPOWER OTHERS! "
Designing apps & games for science and education
Systemic Super Planet
Crash
Orbits GravityKit SAVE/Point
kiosk
Open sourced on GitHub
http://github.com/stefano-meschiari

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My work in a nutshell
THE SCIENCE SIDE...
Getting astronomical data
(telescope observations, new discoveries, …)
Writing code
(data analysis, physical simulations, …)
2451000 2452000 2453000 2454000 2455000 2456000 2457000
-30 -20 -10 0 10 20
d[, 1]
d[, 2]
Science

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My work in a nutshell
...AND THE ASTRONOMY EDUCATION SIDE
Writing code
(HTML5/JavaScript web development)
Education
Designing apps & games
(Systemic, Super Planet Crash, SAVE/Point, …)

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Radial Velocity data
DOPPLER EFFECT + LOTS O’ STELLAR NOISE

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Radial Velocity data
DOPPLER EFFECT + LOTS O’ STELLAR NOISE
Cochran’s law (1992)
“Thou shalt not embarrass thyself and
thy colleagues by claiming false planets.”
“Controversial” detections
(about 10%)

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Systemic: a package/IDE for exoplanets
LIVE DEMO TIME! HOPEFULLY NOTHING CRASHES ✌
Systemic
(the oﬄine/science version)

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Systemic’s architecture & entry points
MUST… NOT… FORGET… ANY OF THESE LANGUAGES…
Java
(UI)
Pipe
R
(High-level
scripting)
Dyncall
C
(libsystemic)
Multiple
processes
Multithreaded
Linking
GSL
SWIFT
(FORTRAN)

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Example: HD219134
DATA SPANNING 11 YEARS
-10
0
10
20
2004 2007 2010 2013 2016
Date
Radial velocity [m/s]
Dataset
APF
KECK
Q01
Vogt, Burt, Meschiari+15

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Orbital plot
INNER AND OUTER PLANETARY SYSTEM
1 AU
0.125 AU
Inner planetary system Whole system

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10
Period of planet b
Density
3.0926 3.0930 3.0934
0 1000 3000
Mass of planet b
Density
0.006 0.010 0.014
0 100 200 300
Mean anomaly of planet b
Density
0 50 100 150
0.000 0.010 0.020
Semi-major axis of planet b
Density
0.038470 0.038474 0.038478
0e+00 2e+05 4e+05
Semiamplitude of planet b
Density
1.0 1.5 2.0 2.5
0.0 0.5 1.0 1.5 2.0
Period of planet c
Density
6.761 6.763 6.765 6.767
0 200 400 600
Mass of planet c
Density
0.005 0.010 0.015 0.020
0 50 150 250
Mean anomaly of planet c
Density
0 50 100 150 200
0.000 0.005 0.010 0.015
Semi-major axis of planet c
Density
0.06480 0.06482
0 40000 80000
Semiamplitude of planet c
Density
0.5 1.0 1.5 2.0
0.0 0.5 1.0 1.5 2.0
Period of planet d
Density
22.78 22.80 22.82
0 20 40 60 80
Mass of planet d
Density
0.015 0.025 0.035
0 50 100 150
Mean anomaly of planet d
Density
200 250 300 350
0.000 0.010 0.020
Semi-major axis of planet d
Density
0.14565 0.14575 0.14585
0 5000 15000
Semiamplitude of planet d
Density
1.5 2.0 2.5 3.0
0.0 0.5 1.0 1.5
Period of planet e
Density
46.66 46.70 46.74
0 5 15 25 35
Mass of planet e
Density
0.050 0.060 0.070 0.080
0 20 60 100
Mean anomaly of planet e
Density
240 260 280 300 320
0.00 0.01 0.02 0.03
Semi-major axis of planet e
Density
0.2349 0.2351
0 4000 8000
Semiamplitude of planet e
Density
3.5 4.0 4.5 5.0 5.5
0.0 0.5 1.0 1.5
Period of planet f
Density
93.6 94.0 94.4 94.8
0.0 1.0 2.0
Mass of planet f
Density
0.02 0.03 0.04 0.05
0 20 40 60 80
Mean anomaly of planet f
Density
0 50 100 150 200
0.000 0.004 0.008
Semi-major axis of planet f
Density
0.3735 0.3745 0.3755 0.3765
0 200 600 1000
Semiamplitude of planet f
Density
1.0 1.5 2.0 2.5
0.0 0.5 1.0 1.5
Period of planet g
Density
2050 2150 2250 2350
0.000 0.004 0.008
Mass of planet g
Density
0.25 0.30 0.35 0.40
0 5 10 15 20
Mean anomaly of planet g
Density
0 50 150 250 350
0.000 0.003 0.006
Semi-major axis of planet g
Density
2.95 3.05 3.15 3.25
0 2 4 6 8 10
Semiamplitude of planet g
Density
4.5 5.0 5.5 6.0 6.5 7.0 7.5
0.0 0.4 0.8 1.2
Eccentricity of planet g
Density
0.00 0.10 0.20 0.30
0 2 4 6 8
Long. of periastron of planet g
Density
0 50 150 250 350
0.000 0.004 0.008
Noise, Q01
Density
0.5 1.0 1.5 2.0
0.0 0.5 1.0 1.5 2.0
Noise, KECK
Density
2.0 2.5 3.0 3.5
0.0 0.5 1.0 1.5 2.0
Noise, APF
Density
1.5 2.0 2.5
0.0 0.5 1.0 1.5 2.0
MCMC
NATIVE CODE + MULTITHREADED IMPLEMENTATIONS
Markov-Chain
Monte Carlo

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Residuals
BEAUTIFULLY NORMAL & CORRELATED WITH STELLAR ACTIVITY
-10
-5
0
5
0.20 0.25 0.30 0.35 0.40
Activity
Velocity residuals [m s-1]
2000
2005
2010
2015
Year
Dataset
KECK
APF
Activity
Velocity residuals [m/s]
Q-Q plot of residuals Residuals vs. activity

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Systemic R package
- Bootstrap 
- Cross-validation 
- Local optimization  
Simplex, gradient descent, Levenberg-Marquardt 
- Global optimization  
diﬀerential evolution, simulated annealing, MCMC 
- Long-term integration over millions of years
http://github.com/stefano-meschiari/Systemic2

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Widely used in the community
…INCLUDING AS A CITIZEN SCIENCE TOOL
More than 5,000 registrations, used to discover/
characterize more than 40 planetary systems.
Makes for a great citizen science/authentic science
experience tool.
Fully half of registrations from teachers, students,
and non-academic users.
Peter Jalowiczor Dominick Rowan

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Widely used in the community
…INCLUDING IN THE CLASSROOM
Top complaints:
It’s too hard
to install!
It’s too hard
to use!

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Systemic’s architecture for the Web
MY MAKEFILE HAS A JAVASCRIPT TARGET
Java
(UI)
Pipe
R
(High-level
scripting)
Dyncall
C
(libsystemic)
Multiple
processes
Linking
GSL
SWIFT
(FORTRAN)
Emscripten
“make -f Makeﬁle.js”
JavaScript
(libsystemic.js)
HTML5
(UI)
<br/>

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Systemic Live
RUNS ON YOUR FAVORITE BROWSER (DESKTOP/MOBILE)

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“The online Systemic Console is a real gift to the community. […] I use this site
to train both undergraduate and graduate students – they love the power of
this program.”  
— Debra Fischer, Yale University
“Systemic is simple enough to use that it can provide a hand-on ‘virtual lab’ for
a large general education class, […] students can get a taste of the scientiﬁc
process even before they learn to program” –  
— Eric Ford, Penn State
“[...] After demonstrating the relevant equations in class, students have a good
feel for the physics involved, but not until they start to try to ﬁt real data and
extract real planets do they realize the how subtle, complex, and fun the real
process is. ” 
— Mike Brown, Caltech, Pluto-killer
“I have used Systemic for several years in my class for advanced undergraduate
physics majors. […] Systemic is extremely sophisticated, but easy to use, so it
allows students to get a feeling for the tools used in real exoplanet research.” 
— Jonathan Fortney, UC Santa Cruz
Testimonials

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Systemic Live
Systemic is employed in classes at UT, Caltech, University
of Florida, MIT, SJSU, Delaware, Yale, Columbia, UC Santa
Cruz, and others, reaching ∼500 students to date, and is
a homework set on the recurring MOOC “The Science of
the Solar System”
, taken by ∼13,000 Coursera students.
Started to put a bit more serious thought about online
astronomy education after that…

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Super Planet Crash
A “MINIMUM VIABLE GAME” ABOUT GRAVITY

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~15,000,000 games played by ~700,000 users
since April
Huﬃngton Post
The Verge
Physics World
SciAm News
io9
Space.com
VICE
The Creators Project
& others

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Success!
BUT… I BROKE MY WEBSITE $
Imgur, io9
The Verge,
HuﬀPost, VICE,
Hacker News,
Twitter Google Analytics, April-May 2014
CloudFront + some serious
on-the-ﬂy re-engineering of the
game helped.

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What do 15,000,000 clicks look like?
TAKE A GUESS.
Orbital spin
Habitable zone
(get bonus)
I recorded on the
server the
coordinates of
every click on the
game area (the
circle).
Where are most of
the clicks?

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U/L bias
Closer to the controls on the left-
hand side of the window; People pay
more attention to upper ﬁeld of
vision
“Crosshair” bias
Empirical preference for cardinal
directions (related to “oblique
eﬀect”?)
Orbital spin
What do 15,000,000 clicks look like?
[SHOWING A SUBSET OF 100,000]

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SAVE
/Point
http://save-point.io

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Stefano (PI)
Design &
development
Randi
Educational
content
Joel
Music &
story
Greg
Accessibility
for VI people
Pilot project received “seed” funding by UT for 2014-2015.

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Philosophy of the pilot project
OR
Touch Gesture Reference Guide
Press
Double tap
Tap
Press
and
drag
Drag
Press
and tap,
then drag
1 2
Press
and tap
Multi-finger
tap
1 2

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• A suite of apps & games will
provide students at all levels with a
“virtual astronomy lab” in browser 
No installation hassle, can run on
mobile platforms, easily accessible
anywhere.
OR
Press
Double tap
Tap
Press
and
drag
Drag
Press
and tap,
then drag
1 2
Press
and tap
Multi-finger
tap
1 2

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anywhere.
• Prioritize accurate physics, real
astronomical datasets, game-level
fun and engaging design.
OR
Press
Double tap
Tap
Press
and
drag
Drag
Press
and tap,
then drag
1 2
Press
and tap
Multi-finger
tap
1 2

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anywhere.
• Easy scoring/grading systems for
instructors.
OR
Press
Double tap
Tap
Press
and
drag
Drag
Press
and tap,
then drag
1 2
Press
and tap
Multi-finger
tap
1 2
 
Classroom scores

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anywhere.
• Easy scoring/grading systems for
instructors.
• Open source and easily
customizable by schools and
instructors.
OR
Press
Double tap
Tap
Press
and
drag
Drag
Press
and tap,
then drag
1 2
Press
and tap
Multi-finger
tap
1 2
 
Classroom scores

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Orbits
• An HTML5/JavaScript game (using
Canvas) 
Backbone + Paper.js 
• All the level logic (story,
interactions, properties) in an easy-
to-edit YAML ﬁle 
Working on a customization interface
for instructors

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Interactive small-scale exhibi
A cut-down version of our
applications could be ideal
for small astronomy demos
and exhibits.
Our group just got a small
department grant to outﬁt
several ﬂoors of our
buildings with wall-mounted
iPads running educational
apps.
A lot of kids don’t know
how to use a trackpad or a
mouse!
Small-scale exhibits, interactive kiosks,
activities for Visually Impaired users
Touch-based (+sound/haptic feedback)

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At SXSW Gaming Expo
Seattle Museum of Flight
Interactive kiosks at UT
In classrooms

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0.125 AU
My work: overview
Systemic
• A tool to analyze exoplanetary data
• A virtual lab for teachers & students
SAVE/Point
• A pilot platform for education
• 4 games and apps ready to
play
• Discovering new exoplanets
• Understand how they form
• Creating apps for education & outreach
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-5 0 5 10
Time [JD]
RV, Planet b [m/s]
Q01 KECK APF
0 1 2 3 4 5 6 7
-10 -5 0 5
Time [JD]
RV, Planet c [m/s]
Q01 KECK APF
-10 -5 0 5 10
RV, Planet f [m/s]
Q01 KECK APF
0 20 40 60 80
-10 -5 0 5 10
Time [JD]
RV, Planet g [m/s]
Q01 KECK APF
0 500 1000 1500 2000
-10 -5 0 5 10
Time [JD]
RV, Planet h [m/s]
Q01 KECK APF
-5 0 5
Residuals [m/s]
Thank you!

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Systemic R package
1 10 100 1000 10000
0 10 20 30
[1] Residuals for 0-planet fit
Period [d]
Normalized power
Lomb-Scargle
periodograms

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Case study: HD219134
SUBSTANTIAL VARIABILITY
●
10−3
10−2
10−1
100
101
0.1 1.0
S−index median
S−index dispersion
Observations
●
●
●
●
●
●
0
50
100
150
200
250
●
●
HD 219134
KECK stars
Median activity
Activity variability

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Check for stellar activity
IS THE RV SIGNAL CORRELATED WITH THE ACTIVITY?
-10
0
10
0.20 0.25 0.30 0.35 0.40
Activity
Velocity [m s-1]
2000
2005
2010
2015
Year
Dataset
KECK
APF

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[1997,2008] (2008,2012] (2012,2015]
-10
0
10
0.20 0.25 0.30 0.35 0.40 0.20 0.25 0.30 0.35 0.40 0.20 0.25 0.30 0.35 0.40
Activity
Velocity [m s-1]

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Planetary parameters
EXTRACTED FROM THE MARKOV-CHAIN MONTE CARLO OUTPUT

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-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
-400 -200 0 200 400
Lag
Correlation

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Model comparison

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Systemic R package - HD32963
P M MA e ω a K Noise Trend
P
Density
M
Density
MA
Density
e
Density
ω
Density
a
Density
K
Density
Noise
Density
Trend
Density
Markov-Chain Monte Carlo modeling
1 AU

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Kepler’s 2014 bonanza
More than 700 new planets confirmed!
Image Credit: NASA Ames/SETI/J Rowe

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My work in Astronomy

My work in Astronomy

Stefano Meschiari

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