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Tim Cunningham

I am a postdoctoral research fellow (Leverhulme Trust) in the White Dwarf Research Group within Astronomy and Astrophysics at the University of Warwick working with Pier-Emmanuel Tremblay.

Research Interests

Artist's impression

My research primarily focuses on understanding the nature of convection, in particular convective overshoot, in white dwarf atmospheres using CO5BOLD - a 3D radiation-hydrodynamics code. Convective overshoot is a boundary effect which requires a multi-dimensional treatment to be properly characterised. It causes the mixing of material outside of the layers where convective instabilities live and this is significant for understanding the mass of material mixed by convection, a key parameter in calculations of the mass and composition of accreted material. I study this using passive scalar tracers in 3D simulations which allow us to quantify the macroscopic diffusive properties of the region beneath the convection zone.


Artist's impression

In order to test the higher accretion rates predicted by models of convective overshoot, we recently made the first detection of X-rays from a metal-polluted white dwarf (see the Warwick Press Release here). Utilising the Chandra X-ray Observatory we detected a significant source of soft X-rays at the expected position of G29–38; a heavily-polluted white dwarf with a circumstellar debris disk inferred from infrared observations. When the disrupted planetary material leaves the disk and hits the white dwarf surface, a plasma is formed and cools via detectable X-ray emission. This detection of X-rays provides the "smoking gun" signature of ongoing accretion at these planet-eating stars. [Artist's impression credit: University of Warwick/Mark Garlick]


Publications as first author

5) Cunningham, T., Wheatley, P. J., Tremblay, P.-E., et al. 2022 Nature 602 219
4) Cunningham, T., Tremblay, P.-E., Bauer, E. B., et al. 2021 MNRAS 503 1646
3) Cunningham, T., Tremblay, P.-E., Gentile Fusillo, N. P., et al. 2020 MNRAS 492 3540

From hydrogen to helium: the spectral evolution of white dwarfs as evidence for convective mixing

2) Cunningham, T., Tremblay, P.-E., Freytag, B., et al. 2019 MNRAS 488 2503

Convective overshoot and macroscopic diffusion in pure-hydrogen-atmosphere white dwarfs

1) Cunningham T., Wolf W. M. & Bildsten L. 2015 ApJ 803 76

Photoionization heating of nova ejecta by the post-outburst supersoft source


Publications as co-author

8) Rebassa-Mansergas, A., et al. 2021 MNRAS 505 3165
7) Veras, D., et al. 2021 MNRAS 506 1148
4) Green, M. J., et al. 2020 MNRAS 496 1243
2) Gentile Fusillo, N. P., et al. 2019 MNRAS 482 4570
Full Lists at:

Contributed Presentations

May '22 X-ray Astronomy UK, Leicester, UK - [talk]
May '22 AASTCS 9: Exoplanets IV, Las Vegas, US - [talk, plenary session]
Jan '22 Astrophysics Group, Keele University, Keele, UK - [seminar]
Dec '21 Astrophysics Group, Imperial College London, London, UK - [seminar]
Nov '21 KITP: Transport in Stellar Interiors, KITP, UCSB, California, US - [panel discussion on chemical mixing]
Nov '21 KITP: Probes of Transport in Stars, KITP, UCSB, California, US - [collaborative workshop]
Jun '21 O-MESS: Online Meetings on Evolved Stars and Systems - [talk]
Apr '21 Albert Einstein Institute (MPI): Computational Relativistic Astrophysics Group, Potsdam, DE - [seminar]
Aug '20 KITP Online Reunion Conference: Exostar Redux, KITP, UCSB, California, US - [lighting talk]
Oct '19 IAUS 357: White Dwarfs as probes of fundamental physics and ..., Hilo, Hawaii, US - [talk]
Sept '19 CCC2019: Compressible Convection Conference 2019, Newcastle, UK - [talk]
July '19 NAM2019: National Astronomy Meeting 2019, Lancaster, UK - [talk]
July '18 EuroWD21: 21st European White Dwarf Workshop, Austin, Texas, US - [talk]
April '18 EWASS 2018: European Week of Astronomy and Space Science, Liverpool, UK - [talk]
June '17 Current Challenges in the Physics of White Dwarf Stars, Santa Fe, New Mexico, US - [poster]
July '16 EuroWD16: 20th European White Dwarf Workshop, Warwick, UK - [poster]
July '15 Seventh Meeting on Hot Subdwarfs and Related Objects, Oxford, UK - [poster]

Write to:

Tim Cunningham,
Department of Physics,
University of Warwick,
Coventry CV4 7AL
UK
 

Contact details:

E-Mail:
timothy.cunningham
(at)
warwick.ac.uk

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