Exoplanets and Travelling

+ Data Science and Public Engagement


A short introduction of myself


Hi! I am an astrophysicist hunting for new exoplanets. Since 2018, I am a Torres Fellow at the Massachusetts Institute of Technology (MIT), working with the Transiting Exoplanet Survey Satellite (TESS) team. Whenever I am not searching for new worlds, I enjoy travelling, the outdoors (scuba diving, rock climbing and hiking), and exploring our own Earth.

My PhD was obtained at the University of Cambridge, UK, where I worked in Professor Didier Queloz's group at the Exoplanet Research Centre. My research was focused on how we can distinguish between real exoplanets and stuff that looks like exoplanets, but is not ("false positives"). I worked with the Next Generation Transit Survey, a ground-based array of telescopes on the hunt for Neptune-sized exoplanets.

For my Master’s Thesis, I did something completely different: research in the biophysics lab of Professor George Shubeita at the University of Austin at Texas ("hook 'em horns"). I developed a mathematical model furthering our understanding of animal models of genetic diseases like Alzheimer's and Fragile X.

My physics undergraduate education was at the University of Würzburg, where I studied AGN mega-masers in the multi-wavelength group of Professor Matthias Kadler.

Research Interests: Exoplanets, Stellar Flares, Cool Stars, Habitability

Methods & Techniques : Bayesian Statistics, Machine Learning, Time Series Analysis


(Yellowstone. Credit: M. Günther)


Highlights

Sep 18, Started as a Torres Fellow at MIT, working closely with the TESS science team

Aug 18, Volunteered with Love The Oceans in Mozambique: marine biology field work, scuba diving, and work with the local schools

July 18, Graduated from the University of Cambridge with a PhD in (astro-)physics

Apr 18, Launch of TESS on the SpaceX Falcon 9 from Cape Canaveral

Oct 17, Meeting Nobel laureate Rainer Weiss on the day of his award

Sep 16, Advancing my Spanish for a month at Universidad de La Habana, Cuba with an A.J. Pressland Fund scholarship

Feb 16, Joined Prince Philip, Duke of Edinburgh, and Ambassador Ammon for the Kurt Hahn Dinner in the German Embassy in London

Apr 15, My first visit to Paranal: working on NGTS, and exploring the worlds driest desert, Atacama, and its unbelievable night sky

Jul 15, Discussing my research with Prince Andrew, Duke of York, during his visit to Cambridge's Astrophysics Groups

Oct 14, Started my PhD at the University of Cambridge


My research teams


The Transiting Exoplanet Survey Satellite (TESS)

The Transiting Exoplanet Survey Satellite (TESS) is set to discover thousands of new exoplanets. Launched in April 2018, TESS now monitors millions of stars for temporary drops in brightness, which are caused by planetary transits. It will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances - and maybe even Earth 2.0.

The TESS discovery of Pi Men c (some call it the first TESS planet): video, cnet, sciencenews, dailystar, sciencealert

The TESS discover of HD 21749 b and another planet candidate (some call it `weird'): New York Times


The Next Generation Transit Survey (NGTS)

The Next Generation Transit Survey (NGTS) is an exoplanet hunter based in Paranal, Chile. With its 12 fully robotized 20 cm telescopes, NGTS covers a total field of view of almost 100 sq. deg. on the sky at once. The main goal of NGTS is to find transiting Neptunes that will be suitable for RV follow-up and mass measurements using current and future instruments such as HARPS and ESPRESSO.


(Launch of TESS. Credit: M. Günther)


Summary of my research


How do stellar flares impact habitability?

Why care about flares? Because flares can impact habitability - they may erode exoplanets' atmospheres, but might also trigger the genesis of life. And all of this is especially important around M-dwarfs! To model flares, we use our public allesfitter code (Günther&Daylan, in prep.). It not only models exoplanets&binaries and red noise (with GPs), but also robustly selects the appropriate model for potentially complex flares via Bayesian evidence. Using Nested Sampling, we can compute the Bayes factors of diffferent models - pure noise, 1 flare, 2 flares, and so on. So what do we find? From the sample of ~25,000 TESS objects we find ~760 flaring stars, ~630 of which are M-dwarfs. Especially the mid M-dwarfs are `flary'. And one of the coolest (no pun intended) things: TESS explores so many bright early to late M-dwarfs! Of course, thanks to Kepler/K2/NGTS/MEarth/EVRYSCOPE and others we already learned some things about their flares - but TESS truly opens up new avenues here. Moreover, we find that fast rotating M-dwarfs are the most likely to flare, solidifying previous findings by other studies. And one of my personal favorites: the large amplitude flare on an M4.5 dwarf, raising the stellar brightness by a factor of 15.7! This goliath is even preceeded by a series of `warm-up' flares. Finally, we link all this flaring to prebiotic chemistry, coronal mass ejections, and ozone depletion. This figure contains a lot of info, and a detailed explanation is beyond this tweet - so if all this raised your interest, have a look at the paper :)

See Günther, M.N. et al., 2019


Unmasking the hidden NGTS-3Ab

NGTS-3 is a very tricky system: at first it looked like a 'simple' Hot Jupiter around a Sun-like star. After taking some radial velocity measurements, it suddenly appeared that there is some 'funkyness' in the data. So it was nearly disregarded as a false positive. After extensive analysis, however, we could save this happy big planet: it turned out to be a Hot Jupiter in a previously (and still visually) unresolved binary star system.

See Günther, M.N. et al., 2018


Identifying false positives by measuring stellar light to 0.00025 image pixel

Astrophysical false positives are crucial to avoid in a wide-field transit survey like NGTS. Eclipsing binaries with a low-mass companion or grazing eclipses, as well as diluted eclipsing binaries or variable stars in the background can mimic a planet transit and be very costly to follow up. They can best be identified with the centroiding technique: if the photometric flux is lost off-centre during an eclipse, the flux centroid shifts towards the centre of the target star. Although this method has successfully been employed by the Kepler mission, it has previously not been proven feasible from the ground. A new algorithm I developed allows NGTS to detect centroid shifts with a precision of down to 0.00025 pixel. This makes NGTS the first ground-based wide-field transit survey ever to successfully implement this technique for candidate auto-vetting.

See Günther, M.N. et al., 2017b


Optimizing the yield of transit surveys

YETI (Yield Estimator for Transit Instruments) is a Python-based simulator I developed to estimate the yield of planets and false positives for transit surveys like NGTS, Kepler and TESS. It enables to evaluate the influence of field selection, observing strategies, noise properties, detection criteria and false alarm rates. Further, with YETI one can diagnose methods for candidate vetting, and establish appropriate follow-up strategies.

See Günther, M.N. et al., 2017a


(Artist illustration of NGTS-1b. Credit: University of Warwick/Mark Garlick)



Publications

5 first author

17 in total

ADS

ORCID

Google Scholar


Peer-reviewed, lead author

  • Günther, M.N. et al., 2019, Stellar Flares from the First Tess Data Release: Exploring a New Sample of M-dwarfs, submitted
  • Günther, M.N. et al., 2018, Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system, MNRAS, 478 (4): 4720–4737
  • Günther, M.N. et al., 2017b, Centroid vetting of transiting planet candidates from the Next Generation Transit Survey, MNRAS, 472 (1): 295-307
  • Günther, M.N. et al., 2017a, A New Yield Simulator for Transiting Planets and False Positives: Application to the Next Generation Transit Survey, MNRAS, 465 (3): 3379-3389
  • Günther, M.N. et al., 2016, Quantifying and predicting Drosophila larvae crawling phenotypes, Nature Scientific Reports, 6: 27972


Peer-reviewed, co-lead author


Peer-reviewed, co-author


PhD Thesis

(NGTS in Paranal, Chile. Credit: G. Lambert )



Outreach


2018

Volunteered for a month with marine biologists in Mozambique, teaching (and learning) about the oceans, marine life, pollution and conservation - and sprinkled in some astrophysics.

2017

Hosted a public evening on exoplanets in Burgkunstadt Germany, and gave a visiting tutorial for the high school's astrophysics course. Featured in the local German news (web1, web2) and on the school's website (web1, web2).

Tutored high-performing high-school students in physics and astronomy over multiple months, as part of 'The Brilliant Club' - a charitable programme focussed on low-participation neighbourhoods (web).

2016

Bringing exoplanet science to 8-12 year old pupils in Barton Road and Milton Road Primary Schools. Thanks to the Cambridge Science Festival Roadshow for this fantastic programme (leaflet).

2015

Initiated a public evening on exoplanets hosted at my former high school, Gymnasium Burgkunstadt, in Germany. The evening was featured in articles in the Obermain Tagblatt (web) and on the school's website (web).


(Outreach event, Germany. Credit: OT/Adriane Lochner )


Contact

Department of Physics,

and Kavli Institute for Astrophysics and Space Research

Massachusetts Institute of Technology

Cambridge, MA 02139, USA

Email: maxgue [at] mit.edu

Twitter: @M_N_Guenther

(Sunset at Paranal, Chile.

Credit: M. Günther)