Helen Giles


About Me

Originally from a town in the North West of England, I was fascinated with astronomy from a young age.
After attending a summer space school for three years, I independently studied for a GCSE in Astronomy during the last four months of my final year of high school.
Two years later, I achieved the necessary grades to attend the University of St Andrews in Scotland to study Astrophysics.

In St Andrews, I opted to enter into the second year - taking each astronomy course possible.
During the course of my degree I undertook two summer internships in exoplanet atmospheres and detection, with Christiane Helling in St Andrews and Chas Beichman in Pasadena.
Then for my final year Masters project, studying starspot lifetimes from Kepler data, was supervised by Raphaëlle Haywood and Andrew Collier Cameron.

After earning an integrated Masters degree in Astrophysics (1st class with Honours), I secured a PhD position at the Observatoire de Genève in Switzerland where I continued my stellar activity work and further exoplanet discovery.

On June 26th 2019 I successfully defended my thesis 'Know thy Star, Know thy Planet - Disentangling Planet Discovery & Stellar Activity' which can be found here.


My Research

Fiery Sun


Whilst we understand sunspots extremely well, our knowledge of these magnetic regions on other stars is limited. And given we can't resolve stellar surfaces to the same degree as we can observe the solar surface, we need to extrapolate information from another source.

During my Masters' project and PhD, I successfully determined the lifetimes of starspots from photometry obtained from the Kepler mission, and how they depend on the stellar spectral type in collaboration with Raphaëlle Haywood and Andrew Collier Cameron.

For details, see the paper available on arXiv.


Exoplanet Discovery & Characterisation

In my role as the CHEOPS PhD student, I conducted the exoplanet discovery and radial velocity follow-up of publicly released data from the K2 mission - in collaboration with Exoplanet groups around Europe, the USA and Chile. This resulted in three planet discoveries (one from a summer internship, two during my PhD).

For details, see the papers for Kepler-1654 b, K2-140 b and EPIC248847494b available on arXiv.



Total Publications: 19 | Total Refereed: 16 | First Author: 3 | h-index: 9

HD 213885b: A transiting 1-day-period super-Earth with an Earth-like composition around a bright (V = 7.9) star unveiled by TESS

Espinoza, N.; Brahm, R.; Henning, T.; Jordán, A.; Dorn, C.; Rojas, F.; Sarkis, P.; Kossakowski, D.; Schlecker, M.; Díaz, M.R.; Jenkins, J.S.; Aguilera-Gomez, C.; Jenkins, J.M.; Twicken, J.D.; Collins, K.A.; Lissauer, J.; Armstrong, D.J.; Adibekyan, V.; Barrado, D.; Barros, S.C.C.; Battley, M.; Bayliss, D.; Bouchy, F.; Bryant, E.M.; Cooke, B.F.; Demangeon, O.D.S.; Dumusque, X.; Figueira, P.; Giles, H.; Lillo-Box, J.; Lovis, C.; Nielsen, L.D.; Pepe, F.; Pollacco, D.; Santos, N.C.; Sousa, S.G.; Udry, S.; Wheatley, P.J.; Turner, O.; Marmier, M.; Ségransan, D.; Ricker, G.; Latham, D.; Seager, S.; Winn, J.N.; Kielkopf, J.F.; Hart, R.; Wingham, G.; Jensen, E.L.N.; Hełminiak, K.G.; Tokovinin, A.; Briceño, C.; Ziegler, C.; Law, N.M.; Mann, A.W.; Daylan, T.; Doty, J.P.; Guerrero, N.; Boyd, P.; Crossfield, I.; Morris, R.L.; Henze, C.E.; Chacon, A.D.

Monthly Notices of the Royal Astronomical Society (pending, 2020)

Using HARPS-N to characterize the long-period planets in the PH-2 and Kepler-103 systems

Dubber, S.C.; Mortier, A.; Rice, K.; Nava, C.; Malavolta, L.; Giles, H.; Coffinet, A.; Charbonneau, D.; Vanderburg, A.; Bonomo, A.S.; Boschin, W.; Buchhave, L.A.; Collier Cameron, A.; Cosentino, R.; Dumusque, X.; Ghedina, A.; Harutyunyan, A.; Haywood, R.D.; Latham, D.; López-Morales, M.; Micela, G.; Molinari, E.; Pepe, F.A.; Phillips, D.; Piotto, G.; Poretti, E.; Sasselov, D.; Sozzetti, A.; Udry, S.

Monthly Notices of the Royal Astronomical Society, Volume 490:4, 5103-5121 (2019)

Exoplanet Imitators: A test of stellar activity behavior in radial velocity signals

Nava, C.; López-Morales, M.; Haywood, R.D.; Giles, H.A.C.

Submitted to Astrophysical Journal

Exoplanet characterisation in the longest known resonant chain: the K2-138 system seen by HARPS

Lopez, T. A.; Barros, S. C. C.; Santerne, A.; Deleuil, M.; Adibekyan, V.; Almenara, J. -M.; Armstrong, D. J.; Brugger, B.; Barrado, D.; Bayliss, D.; Boisse, I.; Bonomo, A. S.; Bouchy, F.; Brown, D. J. A.; Carli, E.; Demangeon, O.; Dumusque, X.; Díaz, R. F.; Faria, J. P.; Figueira, P. Foxell, E.; Giles, H.; Hébrard, G.; Hojjatpanah, S.; Kirk, J.; Lillo-Box, J.; Lovis, C.; Mousis, O.; da Nóbrega, H. J.; Nielsen, L. D.; Neal, J. J.; Osborn, H. P.; Pepe, F.; Pollacco, D.; Santos, N. C.; Sousa, S. G.; Udry, S.; Vigan, A.; Wheatley, P. J.

Astronomy & Astrophysics, Volume 631, A90

Optical phase curve of the ultra-hot Jupiter WASP-121b

​Bourrier, V.; Kitzmann, D.; Kuntzer, T.; Nascimbeni, V.; Lendl, M.; Lavie, B.; Hoeijmakers, H. J.; Pino, L.; Ehrenreich, D.; Heng, K.; Allart, R.; Cegla, H. M; Dumusque, X.; Melo, C.; Astudillo-Defru, N.; Caldwell, D. A.; Cretignier, M.; Giles, H.; Henze, C. E.; Jenkins, J. Lovis, C.; Murgas, F.; Pepe, F.; Ricker, G. R.; Rose, M. E.; Seager, S.; Segransan, D.; Suarez-Mascareno, A.; Udry, S.; Vanderspek, R.; Wyttenbach, A.

Submitted to Astronomy & Astrophysics

PhD Thesis

Know thy Star, Know thy Planet - Disentangling Planet Discovery & Stellar Activity

Giles, H. A. C.

PhD Thesis, Université de Genève (2019)

The CORALIE survey for southern extrasolar planets. XVIII. Three new massive planets and two low-mass brown dwarfs at greater than 5 AU separation

Rickman, E. L.; Ségransan, D.; Marmier, M.; Udry, S.; Bouchy, F.; Lovis, C.; Mayor, M.; Pepe, F.; Queloz, D.; Santos, N. C.; Allart, R.; Bonvin, V.; Bratschi, P.; Cersullo, F.; Chazelas, B.; Choplin, A.; Conod, U.; Deline, A.; Delisle, J. -B.; Dos Santos, L. A. Figueira, P.; Giles, H. A. C.; Girard, M.; Lavie, B.; Martin, D.; Motalebi, F.; Nielsen, L. D.; Osborn, H.; Ottoni, G.; Raimbault, M.; Rey, J.; Roger, T.; Seidel, J. V.; Stalport, M.; Suárez Mascareño, A.; Triaud, A.; Turner, O.; Weber, L.; Wyttenbach, A.

Astronomy & Astrophysics, Volume 625, A71 (2019)

The solar benchmark: rotational modulation of the Sun reconstructed from archival sunspot records

Morris, B.M.; Davenport, J.R.A.; Giles, H.A.C.; Hebb, L.; Hawley, S.L.; Angus, R.; Gilman, P.A.; Agol, E.

Monthly Notices of the Royal Astronomical Society, Volume 484:3, 3244-3250 (2019)

A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS

​Nielsen, L. D.; Bouchy, F.; Turner, O.; Giles, H.; Mascareño, A. Suárez; Lovis, C.; Marmier, M.; Pepe, F.; Ségransan, D.; Udry, S.; Otegi, J. F.; Ottoni, G.; Stalport, M.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J. N.; Jenkins, J. M.; Kane, S. R. Wittenmyer, R. A.; Bowler, B.; Crossfield, I.; Horner, J.; Kielkopf, J.; Morton, T.; Plavchan, P.; Tinney, C. G.; Zhang, Hui; Wright, D. J.; Mengel, M. W.; Clark, J. T.; Okumura, J.; Addison, B.; Caldwell, D. A.; Cartwright, S. M.; Collins, K. A.; Francis, J.; Guerrero, N.; Huang, C. X.; Matthews, E. C.; Pepper, J.; Rose, M.; Villaseñor, J.; Wohler, B.; Stassun, K.; Howell, S.; Ciardi, D.; Gonzales, E.; Matson, R.; Beichman, C.; Schlieder, J.

Astronomy & Astrophysics, Volume 623, A100 (2019)

Transiting planet candidate from K2 with the longest period

Giles H.A.C.; Osborn, H.P.; Blanco-Cuaresma, S.; Lovis, C.; Bayliss, D.; Eggenberger, P.; Collier Cameron, A.; Kristiansen, M.H.; Turner, O.; Bouchy, F.; Udry S.

Astronomy & Astrophysics, Volume 615, L13 (2018)

An Earth-sized exoplanet with a Mercury-like composition

Santerne, A.; Brugger, B.; Armstrong, D.J.; Adibekyan, V.; Lillo-Box, J.; Gosselin, H.; Aguichine, A.; Almenara, J.-M.; Barrado, D.; Barros, S.C.C.; Bayliss, D.; Boisse, I.; Bonomo, A.S.; Bouchy, F.; Brown, D.J.A.; Deleuil, M.; Delgado Mena, E.; Demangeon, O.; Díaz, R.F.; Doyle, A.; Dumusque, X.; Faedi, F.; Faria, J. P.; Figueira, P.; Foxell, E.; Giles, H.A.C.; Hébrard, G.; Hojjatpanah, S.; Hobson, M.; Jackman, J.; King, G.; Kirk, J.; Lam, K.W.F.; Ligi, R.; Lovis, C.; Louden, T.; McCormac, J.; Mousis, O.; Neal, J.J.; Osborn, H.P.; Pepe, F.; Pollacco, D.; Santos, N.C.; Sousa, S.G.; Udry, S.; Vigan, A.

Nature Astronomy, Volume 2, 393-400 (2018)

An Accurate Mass Determination for Kepler-1655b, a Moderately Irradiated World with a Significant Volatile Envelope

Haywood, R.D.; Vanderburg, A.; Mortier, A.; Giles, H.A.C.; López-Morales, M.; Lopez, E.D.; Malavolta, L.; Charbonneau, D.; Collier Cameron, A.; Coughlin, J.L.; Dressing, C.D.; Nava, C.; Latham, D.W.; Dumusque, X.; Lovis, C.; Molinari, E.; Pepe, F.; Sozzetti, A.; Udry, S.; Bouchy, F.; Johnson, J.A.; Mayor, M.; Micela, G.; Phillips, D.; Piotto, G.; Rice, K.; Sasselov, D.; Ségransan, D.; Watson, C.; Affer, L.; Bonomo, A.S.; Buchhave, L.A.; Ciardi, D.R.; Fiorenzano, A.F.; Harutyunyan, A.

The Astronomical Journal, Volume 155, Issue 5, 203 (2018)

K2-140b - an eccentric 6.57 d transiting hot Jupiter in Virgo

Giles, H.A.C.; Bayliss, D.; Espinoza, N.; Brahm, R.; Blanco-Cuaresma, S.; Shporer, A.; Armstrong, D.; Lovis, C.; Udry, S.; Bouchy, F.; Marmier, M.; Jordán, A.; Bento, J.; Collier Cameron, A.; Sefako, R.; Cochran, W. D.; Rojas, F.; Rabus, M.; Jenkins, J.S.; Jones, M.; Pantoja, B.; Soto, M.; Jensen-Clem, R.; Duev, D.A.; Salama, M.; Riddle, R.; Baranec, C.; Law, N.M.

Monthly Notices of the Royal Astronomical Society, Volume 475:2, 1809-1818 (2018)

Validation and Initial Characterization of the Long-period Planet Kepler-1654 b

Beichman, C.A.; Giles, H.A.C.; Akeson, R.; Ciardi, D.; Christiansen, J.; Isaacson, H.; Marcy, G.M.; Sinukoff, E.; Greene, T.; Fortney, J.J.; Crossfield, I.; Hu, R.; Howard, A. W.; Petigura, E. A.; Knutson, H.A.

The Astronomical Journal, Volume 155, Issue 4, 158, 11, (2018)

Understanding Stellar Contamination in Exoplanet Transmission Spectra as an Essential Step in Small Planet Characterization

Apai, D.; Rackham, B.V.; Giampapa, M.S.; Angerhausen, D.; Teske, J.; Barstow, J.; Carone, L.; Cegla, H.; Domagal-Goldman, S.D.; Espinoza, N.; Giles, H.A.C.; Gully-Santiago, M.; Haywood, R.; Hu, R.; Jordan, A.; Kreidberg, L.; Line, M.; Llama, J.; López-Morales, M.; Marley, M.S.; de Wit, J.

White paper submitted to the NAS Committee on Exoplanet Science Strategy

A Kepler study of starspot lifetimes with respect to light-curve amplitude and spectral type

Giles, H.A.C.; Collier Cameron, A.; Haywood, R.D.

Monthly Notices of the Royal Astronomical Society, Volume 472:2, 1618-1627 (2017)

Ground-based photometry of the 21-day Neptune HD 106315c

Lendl, M.; Ehrenreich, D.; Turner, O. D.; Bayliss, D.; Blanco-Cuaresma, S.; Giles, H.; Bouchy, F.; Marmier, M.; Udry, S.

Astronomy & Astrophysics, Volume 603, L5 (2017)

Kepler-21b: A Rocky Planet Around a V = 8.25 Magnitude Star

López-Morales, M.; Haywood, R.D.; Coughlin, J.L.; Zeng, L.; Buchhave, L.A.; Giles, H.A.C.; Affer, L.; Bonomo, A.S.; Charbonneau, D.; Collier Cameron, A.; Consentino, R.; Dressing, C.D.; Dumusque, X.; Figueira, P.; Fiorenzano, A.F.M.; Harutyunyan, A.; Johnson, J.A.; Latham, D.W.; Lopez, E.D.; Lovis, C.; Malavolta, L.; Mayor, M.; Micela, G.; Molinari, E.; Mortier, A.; Motalebi, F.; Nascimbeni, V.; Pepe, F.; Phillips, D.F.; Piotto, G.; Pollacco, D.; Queloz, D.; Rice, K.; Sasselov, D.; Segransan, D.; Sozzetti, A.; Udry, S.; Vanderburg, A.; Watson, C.

The Astronomical Journal, Volume 152, Issue 6, 204 (2016)

Dust in brown dwarfs and extra-solar planets.
IV. Assessing TiO2 and SiO nucleation for cloud formation modelling

Lee, G.; Helling, Ch.; Giles, H.A.C.; Bromley, S.T.

Astronomy & Astrophysics, Volume 575, A11 (2015)


Talks & Posters


RAS Specialist Discussion Meeting
High Precision Photometry for Exoplanet and Time Domain Astronomy

8 November 2019

Hijacking Exoplanet Missions for the Stellar Cause

A talk given at the Royal Astronomical Specialist Meeting on High Precision Photometry for Exoplanet and Time Domain Astronomy in London, UK.

Contact Me

If you want to get in touch, I’d love to hear from you! You can either send me a message or find me on social media.


© 2020 by Helen Giles - All opinions expressed are my own