Tag Archive for 'planets'

Discovery of the Fomalhaut C debris disc

This isn’t a photo for a change. It’s a graphic from a press release about my discovery of a debris disk around Fomalhaut C.

Artists illustration of Fomalhaut C, with Fomalhaut A in the background. Credit: Amanda Smith

Artist’s illustration of Fomalhaut C, with Fomalhaut A in the background. Credit: Amanda Smith

The story has travelled far, including (but not limited to) ABCastrobites, Centauri Dreams, CNES & CNRS (French), Discovery News, Natureslashdot & Universe Today.

Planets or soap bubbles?

Planets or soap bubbles? these photos are beautiful…


Warrumbungle National Park

I’m at Siding Spring Observatory near Coonabarabran in NSW this week. I’m looking for planets via the transit technique for my friend Dan. The observatory is situated in a national park, with great views of the park and surrounding terrain.


There are more photos here.

Hot Super-Earths: accepted!

We have received the excellent news that my third paper has been accepted to ApJ. The paper is about possible mechanisms by which Earth-Neptune (low-)mass planets can reach very close orbits. Using standard models we find trends that might be found by future discoveries, and think about what we can learn from them.

Discovery of low-mass planets (which don’t have large Juipter-like atmospheres) will be particularly interesting, because they may be habitable due to (maybe) having solid surfaces. Unfortunately planets are much easier to find when they’re orbiting very close to their parent stars, and too hot to be habitable. Therefore, if they exist, the first decent sample of low mass planets will be discovered in short-period, close-in orbits.

It’s unlikely that planets in these orbits would form there, because it’s hard to form anything at all close to the star. Therefore, from a formation point of view, there are two main ways these planets
could get to close-in orbits after forming further out: by scattering off other planets, or by migrating through the disk out of which they form. In our paper, we show that planets that scatter will be hard to detect, and that migration is a better mechanism.

At present, very little is known about migration of planets in the “super-Earth” mass range, so discovery of these planets should tell us something about how migration works. Alternatively, we might not find any low-mass planets in short-period orbits, which would tell us that migration doesn’t work how current wisdom says. So either way we learn something!

The paper is posted on astro-ph for now, until the journal publishes it.

Third paper resubmitted

Thanks to a nice referees report, and some simulations finally finishing, I submitted a revised version of our “Hot super-Earths” paper this morning. Hopefully all will be well and that will be number three!



I am a Royal Society University Research Fellow based in the Astronomy and Astrophysics Group at the University of Warwick, UK. I work on various theoretical and observational aspects of planet formation and the end results – planets and debris disks – as seen around nearby stars. Among other topics, I have recently worked on transiting dust populations, what debris disks may tell us about the alignment of orbits in stellar and planetary systems, and the possible impact of exo-Zodiacal dust on future missions to image Earth-like planets around other stars. I am involved in many collaborations, including ongoing surveys such as LBTI HOSTS and NaCo ISPY.


KIC8462852 PDS110
HD181327 HD181327 tau Ceti
Fomalhaut C kappa CrB HD181327
eta Crv 61 Vir and GJ 581 snow line


Refereed Papers

These, and other related proceedings and proposals, can be found on ADS or orcid.org.
2017 (1/15|20/74)
  • Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation, Wyatt et al, MNRAS in press
  • Optical Polarimetry of KIC 8462852 in May-August 2017, Steele et al, MNRAS in press
  • Extinction and the Dimming of KIC 8462852, Meng et al, ApJ in press [ ADS | press ]
  • The First Scattered Light Image of the Debris Disk around the Sco-Cen target HD 129590, Matthews et al., ApJL in press [ ADS ]
  • SONS: The JCMT legacy survey of debris discs in the submillimetre, Holland, Matthews, Kennedy et al, MNRAS in press [ ADS ]
  • Periodic Eclipses of the Young Star PDS 110 Discovered with WASP and KELT Photometry, Osborn et al, MNRAS in press [ ADS | press ]
  • A Complete ALMA Map of the Fomalhaut Debris Disk, MacGregor et al, MNRAS in press [ ADS | press ]
  • Detection of exocometary CO within the 440 Myr-old Fomalhaut belt: a similar CO+CO$_2$ ice abundance in exocomets and Solar System comets, Matra et al, MNRAS in press [ ADS | press ]
  • ALMA observations of the multiplanet system 61 Vir: What lies outside super-Earth systems?, Marino et al, MNRAS in press [ ADS ]
  • The Northern Arc of epsilon Eridani’s Debris Ring as Seen by ALMA, Booth et al, MNRAS in press [ ADS ]
  • Predictions for the secondary CO, C and O gas content of debris discs from the destruction of volatile-rich planetesimals, Kral et al, MNRAS in press [ ADS | press ]
  • The transiting dust clumps in the evolved disk of the Sun-like UXOr RZ Psc, Kennedy et al, RSOS [ ADS | RSOS ]
  • First scattered-light images of the gas-rich debris disk around 49 Ceti, Choquet et al, ApJL [ ADS ]
  • Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD 206893, Milli et al, A&A [ ADS ]
  • ALMA observations of the eta Corvi debris disc: inward scattering of CO-rich exocomets by a chain of 3-30 M_Earth planets?, Marino et al, MNRAS [ ADS ]
2016 (0/12|19/59)
  • The SHARDDS survey: first resolved image of the HD114082 debris disk in Lower Centaurus Crux with SPHERE, Wahhaj, Milli, Kennedy et al, A&A [ ADS ]
  • Dipper disks not inclined towards edge-on orbits, Ansdell et al, MNRASL [ ADS ]
  • ALMA Observations of the Debris Disk of Solar Analogue tau Ceti, MacGregor et al, ApJ [ ADS ]
  • Deep LMT/AzTEC millimeter observations of epsilon Eridani and its surroundings, Chavez et al, MNRAS [ ADS ]
  • The Gaia-ESO Survey: revisiting the Li-rich giant problem, Casey et al, MNRAS [ ADS ]
  • Exocometary gas in the HD 181327 debris ring, Marino et al, MNRAS [ ADS | press ]
  • Effects of disc asymmetries on astrometric measurements, Kral et al, A&A [ ADS ]
  • Polarization measurements of hot dust stars and the local interstellar medium, Marshall et al, ApJ [ ADS ]
  • Nulling Data Reduction and On-Sky Performance of the Large Binocular Telescope Interferometer, Defrere et al, ApJ [ ADS ]
  • Planet Hunters X. KIC 8462852 – Where’s the Flux? Boyajian et al, MNRAS [ ADS | press | kickstarter ]
  • IR-excesses around nearby Lambda Boo stars are caused by debris disks rather than ISM bow waves, Draper et al, MNRAS [ ADS ]
  • Young “Dipper” Stars in Upper Sco and rho Oph Observed by K2, Ansdell et al, ApJ [ ADS ]
2015 (4/11|19/47)
  • The AU Mic debris disk: far-infrared and submillimeter resolved imaging, Matthews, Kennedy et al, ApJ [ ADS ]
  • Kuiper belt structure around nearby super-Earth host stars, Kennedy et al, MNRAS [ ADS ]
  • Warm exo-Zodi from cool exo-Kuiper belts: the significance of P-R drag and the inference of intervening planets, Kennedy & Piette, MNRAS [ ADS ]
  • Stellar Multiplicity and Debris Disks: An Unbiased Sample, Rodriguez et al, MNRAS [ ADS ]
  • Constraining the orbits of sub-stellar companions imaged over short orbital arcs, Pearce, Wyatt, & Kennedy, MNRAS [ ADS ]
  • Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts? Results from the Herschel DEBRIS and DUNES Surveys, Moro-Martin, Marshall, Kennedy, et al., ApJ [ADS ]
  • Five steps in the evolution from protoplanetary to debris disk, Wyatt, Panic, Kennedy, & Matra, Ap&SS [ ADS ]
  • Exo-zodi modelling for the Large Binocular Telescope Interferometer, Kennedy et al, ApJS [ ADS | PDF ]
  • Target Selection for the LBTI Exozodi Key Science Program, Weinberger, Bryden, Kennedy et al, ApJS [ ADS | PDF ]
  • First-light LBT nulling interferometric observations: warm exozodiacal dust resolved within a few AU of eta Crv, Defrere et al, ApJ [ ADS | PDF | press ]
  • Nature or nurture of coplanar Tatooines: the aligned circumbinary Kuiper belt analogue around HD 131511, Kennedy, MNRAS Letters [ ADS | PDF ]
2014 (3/14|15/36)
  • An unbiased study of debris discs around A-type stars with Herschel, Thureau et al, MNRAS [ ADS | PDF ]
  • Towards chemical constraints on hot jupiter migration, Madhusudhan, Amin, & Kennedy, ApJL [ ADS | PDF ]
  • Interpreting the extended emission around three nearby debris disc host stars, Marshall et al, A&A [ ADS ]
  • Do two temperature debris disks have multiple belts? Kennedy & Wyatt, MNRAS [ ADS | PDF ]
  • The Debris Disk of Solar Analogue tau Ceti: Herschel Observations and Dynamical Simulations of the Proposed Multiplanet System, Lawler, di Francesco, Kennedy et al, MNRAS [ ADS | PDF | press ]
  • A Herschel PACS survey of brown dwarfs in IC 2391: Limits on primordial and debris disk fractions, Riaz & Kennedy, MNRAS [ ADS | PDF ]
  • Correlations between the stellar, planetary, and debris components of exoplanet systems observed by Herschel, Marshall et al, A&A [ ADS | PDF ]
  • Spatially Resolved Imaging of the Two-Component eta Crv Debris Disk with Herschel, Duchene et al, ApJ [ ADS | PDF ]
  • Evolution from protoplanetary to debris discs: The transition disc around HD 166191Kennedy et al, MNRAS [ ADS | PDF ]
  • Discovery of the Fomalhaut C debris diskKennedy et al, MNRAS Letters [ ADS | PDF | press | more press ]
  • Alignment in star-debris disc systems seen by Herschel, Greaves, Kennedy, et al, MNRAS Letters [ ADS | PDF ]
  • Herschel Observations of Debris Discs Orbiting Planet-hosting Subgiants, Bonsor, Kennedy, et al, MNRAS [ ADS | PDF ]
  • Imaged sub-stellar companions: not as eccentric as they appear? The effect of an unseen inner mass on derived orbits, Pearce, Wyatt, & Kennedy, MNRAS [ ADS | PDF ]
  • Resolved imaging of the HR 8799 debris disk with Herschel, Matthews, Kennedy, et al, ApJ [ ADS | PDF ]

2013 (2/7|12/22)

  • Star – Planet – Debris Disk Alignment in the HD 82943 system: Is planetary system coplanarity actually the norm?, Kennedy et al, MNRAS [ ADSPDF ]
  • First results of the SONS survey: submillimetre detections of debris discs, Panic et al, MNRAS [ ADS | PDF]
  • The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectabilityKennedy & Wyatt, MNRAS [ ADS | PDF ]
  • Spatially Resolved Images of Dust Belt(s) Around the Planet-hosting Subgiant Kappa CrB, Bonsor, Kennedy et al, MNRAS [ ADS | PDF | press ]
  • Resolved debris disks around A stars in the Herschel DEBRIS survey, Booth, Kennedy et al, MNRAS [ ADS | PDF ]
  • Millimeter Emission Structure in the first ALMA Image of the AU Mic Debris Disk, MacGregor et al, ApJL [ ADS | PDF ]
  • The Debris Disk around gamma Doradus Resolved with Herschel, Broekhoven-Fiene, Matthews, Kennedy et al, ApJ [ ADS | PDF ]

2012 (3/6|10/15)

  • A DEBRIS Disk Around The Planet Hosting M-star GJ 581 Spatially Resolved with Herschel, Lestrade et al, A&A [ ADS | PDF | press ]
  • Coplanar circumbinary debris disks, Kennedy et al, MNRAS [ ADS | PDF ]
  • Confusion limited surveys: using WISE to quantify the rarity of warm dust around Kepler stars, Kennedy & Wyatt, MNRAS [ ADS | PDF ]
  • Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems, Wyatt, Kennedy et al, MNRAS [ ADS | PDF | press ]
  • A peculiar class of debris disks from Herschel/DUNES – Steep spectral energy distributions, Ertel et al, A&A [ ADS | PDF ]
  • 99 Herculis: Host to a circumbinary polar ring debris disk, Kennedy et al, MNRAS [ ADS | PDF ]

2011 (2/3|7/9)

  • Searching for Saturn’s Dust Swarm: Limits on the size distribution of Irregular Satellites from km to micron sizes, Kennedy et al, MNRAS [ ADS | PDF ]
  • Multi-Wavelength Modelling of the Beta Leo Debris Disc: 1, 2 or 3 planetesimal populations? Churcher et al, MNRAS [ ADS | PDF ]
  • Collisional Evolution of Irregular Satellite Swarms: Detectable Dust around Solar System and Extrasolar PlanetsKennedy & Wyatt, MNRAS [ ADS | PDF ]

2010 (1/2|5/6)

  • Resolving debris discs in the far-infrared: early highlights from the DEBRIS survey, Matthews et al, A&A [ ADS | PDF ]
  • Are Debris Disks Self-Stirred? Kennedy & Wyatt, MNRAS [ ADS | PDF]

2009 (1/1/4)

  • Stellar mass dependent disk dispersal, Kennedy & Kenyon, ApJ [ ADS | PDF ]

2008 (2/2|3/3)

  • Planet formation around stars of various masses: Hot super-Earths, Kennedy & Kenyon, ApJ [ ADS | blog | PDF ]
  • Planet formation around stars of various masses: The snow line and the frequency of gas giants, Kennedy & Kenyon, ApJ [ ADS | blog | PDF ]

2006 (1/1|1/1)

  • Planet formation around low-mass stars: The moving snow line and super-Earths, Kennedy, Kenyon, & Bromley, ApJ [ ADS | blog | PDF | press ]

Conference Proceedings (first author only)

  • Two-temperature debris disks – signposts for directly imaged planets?, Kennedy & Wyatt 2015, IAU314 [ ADS ]
  • The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability, Kennedy & Wyatt 2014, IAU299 [ ADS ]
  • Planet formation around M Dwarfs: The moving snow line and super-EarthsKennedy, Kenyon, & Bromley 2007 [ ADS | blog | PDF ]
Observing programmes (as PI)
  • The frontier of rocky planet formation: are low-mass stars super-efficient?,  ALMA Cycle 5, 2017
  • The Fomalhaut C Debris Disk: Key to the famous eccentric ring around A? ALMA Cycle 5, 2017
  • A unique window on circumbinary planet formation at only 45pc, ALMA Cycle 5, 2017
  • Disk structure and warping in the quadruple HD 98800 system, VLT/SPHERE, 2015
  • Grain size and composition in a planet-forming system with transiting dust clumps, VLT/VISIR, 2015
  • Photometric and spectral variability during terrestrial planet formation, VLT/VISIR, 2014
  • K2 Cycles 2 and 3: Transiting planets as a part of whole planetary systems, K2 target proposal, 2014
  • The Origin of Debris Rings: Planets or Gas?, ALMA Cycles 2 & 3, 2014 & 2015
  • The Fomalhaut C Debris Disk and implications for the Fomalhaut system, SCUBA2 Director’s Discretionary Time, 2013
  • Herschel imaging of a candidate warm debris disk, Herschel Director’s Discretionary Time, 2012
  • Debris Disks as a Tracer of Star and Planet Formation in Binaries, Herschel OT2, 2011
  • An Irregular Dust Cloud around Uranus, Herschel OT1, 2010

Selected observing programmes (as Co-I)

  • Pericenter glow and dust production in the debris disk around HR 4796, PI: J. Olofsson, 2017
  • Proto-planetary disc masses at the end of their lifetime, PI: G. Rosotti, 2017
  • SPHERE imaging of nearby super-Earth planet host systems, PI: M. Read, 2017
  • Spin-orbit alignment in debris disks, VLT/GRAVITY, PI: S Kraus, 2016
  • “Where’s the flux?”: Exocomets or Giant Impact?, Spitzer, PI: H. Meng, 2015/2016
  • Imaging Planets in Sco-Cen Double-Belt Debris Disk Systems, VLT/SPHERE, PI: S. Hinkley, 2015
  • Imaging Planets in the Best-Characterized Double-Belt Debris Disk Systems, VLT/SPHERE, PI: E. Matthews, 2015
  • Awakening the giants, DDo51 survey of the bulge, La Silla 2.2m, PI: M. Ness, 2015
  • Giant planets around nearby young stars – a large NaCo L’ imaging survey, VLT/NaCo GTO 2015-
  • Behind Hubble’s blind spot (a.k.a. SHARDDS), VLT/SPHERE, PI: J. Milli, 2015
  • Characterisation of hot circumstellar dust using optical polarisation, HIPPI, PI: J. Marshall, 2015
  • Imaging Planets in the Best-Characterized Double-Belt Debris Disk Systems, VLT/SPHERE, PI: S. Hinkley, 2014
  • LMT/AzTEC millimetre observations of eps Eri’s cold debris disk, LMT, PI: M. Chavez, 2014
  • CO in bright debris disks within 100pc, Nobeyama 45m, PI: L. Matra, 2014
  • Resolving the narrow Kuiper belt analog around epsilon Eridani, ALMA Cycle 2, PI: A. Jordan, 2014
  • What lies outside super-Earth planetary systems?, ALMA Cycle 2, PI: M. Wyatt, 2014
  • Constraining the Inner Disk Edge of the Solar Analog tau Ceti, ALMA Cycle 2, PI: S. Lawler, 2014
  • Testing the correlation between low mass planets and debris disks, HST, PI: P. Kalas, 2014
  • SpiKeS, Spitzer IRAC survey of the Kepler field, Spitzer, PI: M. Werner, 2013
  • Constraining the structure of the Kappa Cr B planetary system, a unique subgiant, orbited by two companions and a debris disc, HST, PI: A. Bonsor, 2013
  • Finding low-mass planets in debris-disk systems: searching for correlations, SOPHIE, PI: E. Di Folco, 2013
  • Small SpiKeS, Spitzer IRAC pilot survey of one Kepler tile, Spitzer, PI: M. Werner, 2012
  • LBTI exo-zodi key science team, PI: M. Wyatt, 2012
  • SONS, SCUBA-2 Legacy survey PI: B. Matthews, 2012
  • Imaging the Birth Ring of the AU Mic Debris Disk, ALMA, PI: D. Wilner, 2011
  • Confirmation and characterisation of two debris disks around low-mass stars, Herschel, PI: J-F Lestrade, 2011
  • Debris Disks around Low-Mass Planet-Bearing Stars, Herschel, PI: G. Bryden, 2011
  • Debris Disks around Planet-Bearing Stars, Herschel, PI: G. Bryden, 2010
  • Search for a correlation between planets and debris discs around retired A stars, Herschel, PI: A. Bonsor, 2010
  • Testing Planetary Dynamics and Evolutionary History in the HR 8799 Planet/Disc System, Herschel, PI: B. Matthews, 2010
  • DEBRIS, PI: B. Matthews & J. Greaves, Herschel Key Programme, 2009


  • Nature
  • NASA Exoplanet Research Program
  • Monthly Notices of the Royal Astronomical Society
  • Astronomy & Astrophysics
  • The Astrophysical Journal
  • Research in Astronomy and Astrophysics
  • James Clerk Maxwell Telescope TAG


  • Occasional substitute lecturer for Mark Wyatt’s Planetary System Dynamics course
  • Co-supervision of Cambridge PhD students (Tim Pearce, Matthew Read, Sebastian Marino, 2013-)
  • Supervision of Cambridge summer and part III students (2009-)
  • Supervising for Astrophysical Fluid Dynamics (third year course at University of Cambridge, 2013/14/16)
  • Supervising for Mathematical Methods (second your course at University of Cambridge, 2014/15)
  • Graduate student lectures, Nov 2012, IoA [ slides ]

Funding Awarded

  • RAS Undergraduate Bursary for a summer student, April 2015
  • RAS Undergraduate Bursary for a summer student, March 2014
  • RAS Undergraduate Bursary for a summer student, March 2013


  • The exocomet interpretation of KIC 8462852, Mt Stromlo, March 2017
  • Exoplanetary systems, Warwick, October 2016
  • Transiting dust clumps around a Sun-like star, Cambridge, October 2016
  • Exo-Zodi, IoA Colloquium, Cambridge, February 2016
  • Exploding asteroids and fragmented comets, GAIA Alerts, Liverpool, November 2015
  • The exo-Zodi problem, UCL colloquium, 5 October 2015
  • Debris disks: seeing dust, Invited Review, Cosmic Dust, Tokyo, August 2015
  • Warm exo-Zodi from cool exo-Kuiper belts, Pathways II Satellite, July 2015
  • The challenge of the exo-Zodi, EWASS, June 2015
  • A wider view of circumbinary planetary system alignment, EWASS, June 2015
  • The exo-Zodi problem, Exeter colloquium, June 2015
  • Two-temperature debris disks, IAU Symposium 314, Atlanta, May 2015 [ slides ]
  • A wider view of planetary system alignment, UK Exoplanet meeting, Warwick, Apr 2015
  • First results from the LBTI, Cambridge Exoplanets, Jan 2015
  • Exo-Zodi characterisation and origins, Invited talk, MAD Workshop, Santiago, Chile, Nov 2014
  • Planet formation and evolution from debris disks, Invited review, La Cristalera workshop, Madrid, Spain, Sept 2014
  • Disk Modelling results, Invited review, 30 Years of beta Pictoris, Paris, France, Sept 2014 [ slides ]
  • exo-Zodi and exo-Earths, AcrossHR, Cambridge 2014, [ slides ]
  • Theory and Modelling of Debris Disks, Invited review, G. Haro 2014 workshop, INAOE, Mexico
  • Debris disk science with SPICA, SPICA workshop, Leiden, May 2014 [slides ]
  • Debris disks, IPAC, March 2014 [ slides ]
  • The origin of the Fomalhaut stellar and planetary systems, Cambridge Exoplanet group, Jan 2014
  • exo-Zodi and exo-Earths, IAU Symposium 299, Victoria, June 2013 [ slides ]
  • Debris disks and planets, and vice versa, IoA, Cambridge, Feb 2013 [ slides ]
  • Debris disks and their relation to planets, UNSW, Sydney, Dec 2012
  • Debris disks and their relation to planets, Mt Stromlo, Australian Exoplanet Workshop, Dec 2012 [ slides ]
  • Debris disks and their relation to planets, Mt Stromlo, Australian National University, Dec 2012
  • Debris disks and their relation to planets, CAR, Uni of Hertfordshire, Nov 2012 [ slides ]
  • Dust from Saturn’s Irregular Satellites, UK NAM, Mar 2011 [ pdf ]
  • Irregular Satellite Swarms, Mt Stromlo, Feb 2011 [ pdf ]
  • Evolution of Irregular Satellites, Cambridge DAMTP, Feb 2011
  • Herschel DEBRIS Survey, RAS Early Impact of Herschel meeting, January 2011 [ pdf ]
  • Theory of Disk Dispersal around M-Dwarfs, Invited review, August 2010, Cool Stars Splinter on M-Dwarf Planet Formation [ keynote | pdf ]
  • IoA Theory Grant talks, August 2010
  • IoA Star and Planet Formation group, March 2010
  • INI Dynamics of Disks and Planets Final Workshop, Dec 2009
  • IoA Theory Grant talks, Nov 2009
  • Final talk at RSAA [ slides (main) (side) | blog ]
  • Super-Earth talk at ASA 2008 [ slides | blog ]
  • Mid-term review at RSAA [ slides ]
  • Super-earth talk at the Fifth Stromlo Symposium [ slides ]


  • exo-Zodi and prospects for exo-Earth detection at PPVI, 2013 [ poster ]
  • A Circumbinary Polar-ring Debris Disk at Herschel’s View of Star and Planet Formation, 2012 [ poster ]
  • A Circumbinary Polar-ring Debris Disk at Signposts of Planet Formation Conference, 2011 [ poster ]
  • Are debris disks self-stirred? posters at Newton Institute workshops in Cambridge and Edinburgh late 2009 [ poster ]
  • Gas giant frequency poster at ASA 2008 [ poster ]
  • Gas giant frequency poster at Origins of Solar Systems Gordon Conference, 2007 [ poster ]
  • Super-earth poster at the Astronomical Society of Australia Annual Meeting, 2006 [ poster ]

Conference/meeting involvement

  • Co-organiser, Lorentz Center Rocks, Rings, and Rubble workshop, Leiden, 2016
  • Session Chair, Resolving planet formation in the era of ALMA and extreme AO, Santiago, 2016
  • Session chair, Cosmic Dust, Tokyo, 2015
  • LOC, Characterizing Planetary Systems Across the HR Diagram, Cambridge, 2014
  • OC, Stromlo Student Seminars, Australian National University, 2006
  • OC, Harley Wood Winter School, Bateman’s Bay, Australia, 2006



  • Some thoughts on how to create your own space in your research field + tips for fellowship applications. Written for this fellowship event.

My PhD involved thinking about how planet formation depends on the star the planets form around, and what we might learn as more planets orbiting a range of different stars are discovered. I worked with Scott Kenyon of Smithsonian Astrophysical Observatory, part of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA in the USA. This link has a copy of my thesis as submitted (no corrections), though the body is just the first four papers listed here outlined a bit more in blog posts, links below.

  • Stellar mass dependent disk dispersal in the Astrophysical Journal in April 2009 (ApJ v695 p1210) [ ADS ]
  • Planet formation around stars of various masses: Hot super-Earths in the Astrophysical Journal in August 2008 (ApJ v682 p1264) [ ADS | blog entry ]
  • Planet formation around stars of various masses: The snow line and the frequency of gas giants appeared in the Astrophysical Journal in January 2008 (ApJ v673 p502) [ ADS | blog entry ]
  • Planet formation around M Dwarfs: The moving snow line and super-Earths appeared in Astrophysics and Space Science in August 2007 (Ap&SS v311 p9) [ ADS | blog entry ] (this paper is basically a clearer version of the one below)
  • Planet formation around low-mass stars: The moving snow line and super-Earths appeared in the Astrophysical Journal Letters in October 2006 (ApJL v650 p139) [ ADS | blog entry ]

Hot Super-Earths: submitted

So any complaints from referees aside, I’ve submitted a paper today, which gives me something to show for my time here in Boston!


Finding planets

CoRoT is discovering exo-planets at a rate only set by the available resources to follow up the detections

Paper accepted!

After four revisions and seven months of extra (part time) work, my second planet formation paper has been accepted, finally! To sum up the paper in a few sentences…

We think that the likelihood of a star forming at least one gas giant planet increases with the mass of the star. There are two reasons for this: Firstly, the mass of the disks surrounding these stars seems to increase with the mass of the star, and therefore so do the masses of protoplanets that form. Secondly, there is probably a threshold protoplanet mass at which gas accretion occurs and giant planets form. Higher mass stars can therefore form protoplanets above the gas giant forming threshold (and therefore gas giants) more easily, because on average they have more material to do so.

The preprint can be found here.

Planet formation around stars of various masses: The snow line and the frequency of gas giants

This paper was just accepted to the Astrophysical Journal. It considers a simple disk and snow line model, and uses this to predict the likelihood of stars of different masses harbouring gas giants. We think gas giant frequency increases with stellar mass, which is consistent with observations at present.

In summary, observations indicate that disk mass changes roughly with stellar mass, with a wide distribution of masses at a given stellar mass. Therefore more massive stars on average have more material available for planet formation. In addition, there appears to be a threshold protoplanet mass for forming gas giants of about ten Earth masses. Around more massive stars, a higher fraction of the disks can form protoplanets greater than ten Earth masses, so these stars are more likely to form gas giants.

Recent observations by John Johnson indicate a trend of increasing planet frequency with stellar mass, as our paper predicts. Future observations will improve statistics to solidify this result. In the more distant future, planet discoveries will find how processes like migration and scattering have influenced the distribution of planets we can see now.

The paper can be found through the NASA Astrophysics Data System. For more information on my PhD have a look at the main PhD page.

Planet formation around M Dwarfs: The moving snow line and super-Earths

This paper, just accepted to the 5SS conference proceedings, is similar to the ApJ letter here. It uses a smaller increase in surface density at the snow line, based on modern Solar abundance figures for oxygen. A brief comment on type I migration has also been added.

The paper can be found through the NASA Astrophysics Data System. For more information on my PhD have a look at the main PhD page.

Planet formation around low-mass stars: The moving snow line and super-Earths

Our first paper is about how the snow-line in a protoplanetary disk can move due to evolution of the central star, and how it helps the formation of super-Earth mass planets around M Dwarfs. Kennedy, Kenyon & Bromley (2006) uses a simple disk evolution model, with which we are starting to link formation of planets with that of their parent stars.

As a low-mass red dwarf is born it contracts to its main sequence size over hundreds of millions of years. This contraction limits the radiating area of the star, and so it becomes fainter, and the surrounding disk in which planets form becomes cooler.

The cooling of the star means that the distance where ices condense (known as the ‘snow line’) moves inward. In the same way that it is easier to build a snowman above the snow line on a mountain, the presence of ices in the planet forming disk makes it easier to build planets. These planets can be several times larger than our Earth, and are largely made up of ice, roughly similar in structure to Neptune.

The paper had an associated press release, and subsequently generated a bunch of media attention

ANU Press release | CfA Press Release | Uni of Utah press release | Universe Today | Spaceflight Now | Space Daily | Centauri Dreams | PhysOrg | Unexplained Mysteries | Astrobiology Magazine | SciFi Source Book | AstroFind.net | Science Alert | ABC Radio National | ABC Canberra | Nature

The paper can be found through the NASA Astrophysics Data System. For more information on my PhD have a look at the main PhD page.