Jonathan Gagné

PhD Student


Infrared Processing and Analysis Center (IPAC), NASA Exoplanet Science Institute
California Institute of Technology,
Morrisroe Building 770 South Wilson Avenue, Pasadena, CA 91106.
Office : 251
Office Phone : 626-395-2878
Email :
Cell Phone : 626-318-2397

Université de Montréal, Département de Physique.
Pavillon Roger-Gaudry, 2900, boul. Édouard-Montpetit, Montréal,‎ Québec‎, H3T 1J4.
Office : B-436
Office Phone : 514-343-6111 ext.3219
Email :
Current Advisors
California Institute of Technology :

Université de Montréal :



2014 - NOW : IPAC Fellowship 6-month student exchange, California Institute of Technology
            Advisor : Peter Plavchan

2010 - NOW : PhD, Astrophysics, Université de Montréal
            Advisors : René Doyon, David Lafrenière

2007-2010  : Baccalaureate, Physics, Université de Montréal

        My PhD project consists of a whole-sky search for brown dwarfs and low-mass stars (> M5 spectral types) in young, nearby moving groups using Bayesian inference. Starting with a cross-correlation between the 2MASS point-source catalog and the preliminary WISE catalog, we built a sample to which we applied various quality and color-magnitude cuts to filter out contaminants. Using this sample as a starting point, we used 2MASS and WISE magnitudes as well as proper motion estimates from this correlation to infer a membership probability and a statistical estimate for the distance of each object. We then selected the ~100 most probable members of the Beta Pictoris and TW Hydrae moving groups and Tucana-Horologium association for spectroscopic IR follow-up with SpeX, Flamingos-2 and SIMON to assess the youth of these candidates, which is under process.

        More recently, I have started working on Peter Plavchan's NIRRV research group at Caltech, on the analysis and data collection of precise radial velocities (down to a few m/s) of late-K and M dwarfs in the near-infrared (H and K bands), to search for planetary companions.

Research Experience
  • Winter 2014 - Spring 2014 - Precise NIR radial velocity of M dwarfs. IPAC Fellowship, Caltech, US.
  • Summer 2013 - Scientific commissioning of the SIMON camera, CTIO 1.5m, Chile.
  • Summer 2012 to now - Identification of very low-mass candidates to nearby moving groups using Bayesian analysis.
  • Summer 2010 to 2012 - More work with LOCI [PDF - French] and LOCI-PSF, in collaboration with Jérôme Maire.
  • PHY3030 - Baccalaureate Final Project 2009 : Re-analyzing HST data with the LOCI algorithm [PDF - French]
  • Summer internships - 2007 & 2008 : Finding new brown dwarfs with SIMP + Exoplanet secondary transits.

Refereed Publications

H-index of refereed work : 4

#8 - Gagné, J., Faherty, J. K., Cruz, K., Lafrenière, D.Doyon, R., Malo, L, Artigau, É. 2014, The coolest isolated planetary-mass brown dwarf candidate member of TWA, ApJ, 785, L14arxiv:1403.3120. *ADDITIONAL MATERIAL*

#7 - 
Naud, M. E., Artigau, É., Malo, L., Albert, L.Doyon, R.Lafrenière, D., Gagné, J., Saumon, D., Morley, C., Allard, F., Homeier, D., Boucher, A. 2014, Discovery of a Wide Planetary-Mass Companion to the Young M3 Star [], Accepted for publication in the ApJ. arxiv:xxxx.xxxx.

#6 - 
Malo, L., Artigau, É.Doyon, R.Lafrenière, D.Artigau, É., Albert, L.Gagné, J. 2014, BANYAN. III. Radial velocity, rotation and X-ray emission of low-mass star candidates in nearby young kinematic groups, Accepted for publication in the ApJ. arxiv:1402.6053.

#5 - 
Gagné, J.Lafrenière, D.Doyon, R., Malo, L., Artigau, É. 2014, BANYAN. II. Very Low Mass and Substellar Candidate Members to Nearby, Young Kinematic Groups With Previously Known Signs of Youth, ApJ, 783, 121arxiv:1312.5864. *ADDITIONAL MATERIAL*

#4 - 
Delorme, P., Gagné, J., Girard, J. H., Lagrange, A. M., Chauvin, G., Naud, M.-E.Lafrenière, D.Doyon, R., Riedel, A., Bonnefoy, N. Malo, L. 2013, Direct-imaging discovery of a 12-14 Jupiter-mass object orbiting a young binary system of very low-mass stars,  A&A, 553L, 5Darxiv:1303.4525.

#3 - 
Malo, L.Doyon, R.Lafrenière, D.Artigau, É.Gagné, J.Baron, F., Riedel, A. 2013, [BANYAN. I.] Bayesian analysis to identify new star candidates in nearby young stellar kinematic groups, ApJ, 762, 88Marxiv:1209.2077.

#2 - Delorme, P., Gagné, J.Malo, L.Reylé, C.Artigau, É.., Albert, L., Forveille, T., Delfosse, X., Allard, F., Homeier, D. 2012, CFBDSIR2149-0403: a 4-7 Jupiter-mass free-floating planet in the young moving group AB Doradus ?,  A&A, 548A, 26Darxiv:1210.0305.

#1 - Artigau, É.Lafrenière, D.Doyon, R., Liu, M., Dupuy, Trent J. Albert, L.Gagné, J.Malo, L. & Gratadour, D. 2011, Discovery of Two L and T Binaries with Wide Separations and Peculiar Photometric PropertiesApJ, 739, 48-61arxiv:1107.0768.


#4 - Gagné, J., Lafrenière, D., Doyon, R., Malo, L., Faherty, J., Artigau, É. 2013, Bayesian analysis to identify very low-mass members of nearby young stellar kinematic groups,  Mem. S. A. It. Vol. 84, 916. arxiv:1307.1127.

#3 - Delorme, P., Gagné, J., Lannier, J., Lagrange, A. M., Chauvin, G. 2013, Brown Dwarfs or Planets ? Some direct imaging detections that blur the border,  Mem. S. A. It. Vol. 84, 1013.

#2 - Naud, M. E., Artigau, É., Doyon, R., Malo, L., Albert, L., Lafrenière, D., Gagné, J. . 2013, A wide planetary-mass companion to a young M3 star of AB Dor moving group,  EPJ Web of Conferences.  2013EPJWC..4713004N.

#1 - Maire, J., Gagné, J., Lafrenière, D., Doyon, R., Graham, J. R., Véran, J. P., Poyneer, L. A. 2012, Preserving the photometric integrity of companions in high-contrast imaging observations using locally optimized combination of images, Proc. SPIE 8447, Adaptive Optics Systems III, 844760 D. 2012.


UCLA Invited Seminar 2014 - California, United States - April 15, 2014.
Greater IPAC Science Symposium (GISS) Contributed talk 2014 - IPAC/Caltech, California, United States - PDF
IfA Invited Seminar 2014 - IfA, Hawaii, United States - Searching for Brown Dwarfs in Young Moving Groups.
Astropizza 2014 - Université de Montréal - Spectroastrometry to extract the spectra of close binaries (French). [Keynote]
AMNH Invited Seminar 2013 - AMNH, New-York, United States, Young BDs in NYAs. [Keynote]
IPAG Invited Seminar 2013 - IPAG, Grenoble, France, Young BDs in NYAs. [Keynote]
Brown Dwarfs come of Age 2013 - R2 Hotels, Fuerteventura, Spain, Young BDs in NYAs. [Powerpoint]
CRAQ Workshop 2013 - Auberge du Lac-à-l'eau-claire, St-Alexis-des-Monts, Young BDs in NYAs. [Keynote]
Astropizza 2013 - Université de Montréal - Transient Lunar Phenomena (French)
Cool Stars 17 - Barcelona, Spain, 2 minute splinter session + 1 minute poster pop-up presentations.
CRAQ Workshop 2012 - Duchesnay Station, Sainte-Catherine-de-la-Jacques-Cartier, Young Brown Dwarfs
Astropizza 2012 - Université de Montréal - The EIBi modified gravity and its astrophysical implications (French)
SPIRou 2011 - Université de Montréal - Searching for young low-mass stars in the solar neighborhood with SPIRou
Courses 2011 - Université de Montréal - Suppermassive black holes (French)
CRAQ Student Workshop 2011 - Université de Montréal - How does Astrometrynet works and how to use it with IDL
CRAQ Workshop 2011 - Mont-Gabriel, Sainte-Adèle, Québec - Direct imaging of exoplanets with LOCI
Astropizza 2011 - Université de Montréal - The Spin Parameter of Uniformly Rotating Compact Stars (French)
Courses 2010 - Université de Montréal - The Hubble Space Telescope; A crucial tool for modern astronomy
Summer Internship Talk 2009 - The SIMP Survey and MMO Telescope (French)
Summer Internship Talk 2008 - Exoplanet Transits and Brown Dwarfs (French)


David Blank, AMNH, New-York, United States.


JAREPUM 2012 - Astrophysics research groups at Université de Montréal (French)
Astrophysics popularisation for arts - Two meetings with Jean-Pierre Aubé for his creation Exoplanets.
Visitors Popularisation 2011 - Mont-Mégantic Observatory - M stars and exoplanets.
Students Visit 2010 - Université de Montréal - The Brown dwarfs and low-mass stars research group at UdeM.
Visitors Popularisation 2009 - Mont-Mégantic Observatory - Brown Dwarfs and Infrared Cameras.

Faculty Lecturer - PHY1950 - Notions of physics teachers (French) - Fall 2013
Faculty Lecturer - PHY1652 - Special Relativity (French) - Fall 2012
Faculty Lecturer - PHY1652 - Special Relativity (French) - Fall 2011
Teaching Assistant - PHY1620 - Waves and Vibrations (French) - Winter 2010
Teaching Assistant - PHY1652 - Special Relativity (French) - Fall 2009
Teaching Assistant - PHY1651 - Classical Mechanics (French) - Fall 2008

Attended Workshops

Cool Stars 18 (upcoming) - Flagstaff, AZ - Summer 2014
Brown Dwarfs Come of Age - Fuerteventura, SP - Summer 2013
Cool Stars 17 - Barcelona, SP - Summer 2012
JAREPUM 2012 - Montréal, CA - Winter 2012
SPIRou mid-term meeting - Montréal, CA - Winter 2012
Evry-Schatzman School - Roscoff, FR - Summer 2011
CRAQ Student Workshop 2011 - Montréal, CA - Summer 2011
CRAQ 2011 - Mont-Gabriel, CA - Summer 2011
JAREPUM 2011 - Montréal, CA - WInter 2011
Cool Stars 16 - Seattle, US - Summer 2010


        Brown Dwarf Converter iPhone/iPad application for converting BD temperature, spectral type, mass and age. See my AstroBetter post about it.

        A document explaining how to create a very efficient custom search engine on Mac OS X. I use it on a daily basis for SIMBAD, VIZIER, Wikipedia, Google Translate, etc. It saves a lot of time and is really worth the effort.

        A document explaining how to automatically open .fits or .fits.gz files in the darwin version of ds9 on Mac OS X. : An IDL code for querying SIMBAD data from simbad-resolvable object names. : An IDL code for estimating a brown dwarf spectral type/distance from its photometry, using Bayesian Inference.

        A small IDL guide containing tricks for efficient programming.

        An IDL Structure containing the data from Trent Dupuy's Database of Ultracool Dwarf Parallaxes.
Chapter 8   - Quantum Mechanics (In Progress)
Chapter 9   - Thermodynamics (In Progress)
Chapter 10 - Classical Mechanics 2 (In Progress)
Chapter 11 - Instruments for Astronomy (In Progress)
Chapter 13 - Statistical Mechanics (In Progress)
IDL Data reduction pipeline for the 2012 OPIOMM calendar

CRAQLIB IDL codes library (In Progress)

IDL Implementation for, including a user manual to install

        Feel free to contact me by mail if you have any question or remarks concerning these packages. 

Attended Graduate Courses
PHYS643 - Astrophysical Fluids. Andrew Cumming, McGill University. Winter 2012
PHY6771 - Stellar atmospheres. Pierre Bergeron, Université de Montréal. Winter 2012
PHY6795N - Asteroseismology. Gilles Fontaine, Université de Montréal. Winter 2011
PHY6790 - Galactic Astronomy. Claude Carignan, Université de Montréal. Winter 2011
[No ID] - Magnetohydrodynamics. Paul Charbonneau, Université de Montréal. Fall 2010 + Winter 2011
PHY6780 - Instruments for Astronomy. René Doyon, Université de Montréal. Fall 2010

Useful links

My principal hobbies are alpine skiing, kick-boxing, playing violin, piano and guitar.
And playing with mystical floating tops.
My web page

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