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Dr Adam Finley

Postdoctoral Research Associate

Email:

PhD Thesis (completed May 2020):

Constraining the Angular Momentum-loss Rates of the Sun and Other Sun-like Stars

Research Interests:

I wish to understand the complex interaction of magnetic fields and plasma in the solar wind and the winds of other Sun-like stars. The Sun is observed to undergo a 22 year cycle of magnetic activity, over which time the dipolar field polarity is seen to reverse and then be restored. Zeeman Doppler imaging (ZDI) observations have revealed that other Sun-like stars have similarly variable magnetic fields (cyclic or otherwise). Changes to the global magnetic field are expected to influence the amount of angular momentum carried away by these "stellar winds", which then impacts how stars like the Sun spin-down during their lifetimes.

My personal website can be found here: https://adamjamesfinley.github.io/ (contains animations and images from my PhD)

Current Work:

Working in the AWESoMeStars research group, supervised by Sean Matt, I create magnetohydrodynamics (MHD) simulations of stellar winds from Sun-like stars, in which I explore how the structure of the coronal magnetic field influences the morphology and structure of the stellar wind. My research is mainly focused on the creation of semi-analytic "braking laws" that describe the rate of angular momentum loss in stellar winds (based on fundamental stellar properties like mass, radius, magnetic field strength, mass los rate etc). These braking laws can then be used in evolutionary models of stellar spin down, which take into account the changing magnetic field structure observed in many active stars. I have performed a systematic study of the simplest axisymmetric field combinations, dipole, quadrupole and octupole, and produced semi-analytic relations for the angular momentum loss rate in these stellar winds. Following this, I applied these to the variable magnetic field topologies observed for both the Sun and other Sun-like stars. These braking laws have further been explored for a wide range of observed magnetic field configurations by Victor See.

More recently, I have been exploring the impact of non-axisymmetric magnetic field structures on stellar wind angular momentum loss, and seeking to understand the solar angular momentum loss rate (from an astrophysical perspective) using observations from spacecraft immersed in the solar wind itself (e.g. Parker Solar Probe and Solar Orbiter). 

To better visualise the magnetic fields of Sun-like stars (and potentially other magnetised astrophysical phenomena), I have been working with the physics department's 3D printing capability to render handheld models which can be used for research or outreach purposes.

First Author Publications:

2017-

The Effect of Combined Magnetic Geometries on Thermally Driven Winds. I: Interaction of Dipolar and Quadrupolar Fields: 

http://iopscience.iop.org/article/10.3847/1538-4357/aa7fb9

2018-

The Effect of Combined Magnetic Geometries on Thermally Driven Winds. II. Dipolar, Quadrupolar, and Octupolar Topologies: 

http://iopscience.iop.org/article/10.3847/1538-4357/aaaab5

The Effect of Magnetic Variability on Stellar Angular Momentum Loss. I: The Solar Wind Torque During Sunspot Cycles 23 & 24: 

http://iopscience.iop.org/article/10.3847/1538-4357/aad7b6

2019-

The Effect of Magnetic Variability on Stellar Angular Momentum Loss. II. The Sun, 61 Cygni A, ep Eridani, ξ Bootis A, and τ Bootis A: 

https://iopscience.iop.org/article/10.3847/1538-4357/ab12d2

Solar Angular Momentum Loss Over the Past Several Millennia:

https://iopscience.iop.org/article/10.3847/1538-4357/ab3729

Direct Detection of Solar Angular Momentum Loss with the Wind Spacecraft:

https://iopscience.iop.org/article/10.3847/2041-8213/ab4ff4

2020-

The Solar Wind Angular Momentum Flux as Observed by Parker Solar Probe:

https://iopscience.iop.org/article/10.3847/2041-8213/abb9a5

The Contribution of Alpha Particles to the Solar Wind Angular Momentum Flux in the Inner Heliosphere:

https://arxiv.org/abs/2011.00016

Co-Author Publications:

Estimating Magnetic Filling Factors from Zeeman–Doppler Magnetograms - See et al. (2019a): 

https://iopscience.iop.org/article/10.3847/1538-4357/ab1096

Do Non-dipolar Magnetic Fields Contribute to Spin-down Torques? - See et al. (2019b): 

https://iopscience.iop.org/article/10.3847/1538-4357/ab46b2

How Much do Underestimated Field Strengths from Zeeman-Doppler Imaging Affect Spin-down Torque Estimates? - See et al. (2020): 

https://iopscience.iop.org/article/10.3847/1538-4357/ab7918

Alfvén-wave Driven Magnetic Rotator Winds from Low-mass Stars I: Rotation Dependences of Magnetic Braking and Mass-loss Rate - Shoda et al. (2020):

https://iopscience.iop.org/article/10.3847/1538-4357/ab94bf

Parker Solar Probe Observations of Suprathermal Electron Flux Enhancements Originating from Coronal Hole Boundaries - Macneil et al. (2020):

https://academic.oup.com/mnras/article/498/4/5273/5900563

Co-Supervised Summer Student Projects:

  • Amy Hewitt - Direct Detection of Solar Wind Angular Momentum Flux - 2019
  • Siddhant Deshmukh - Long-time Variability of the Solar Angular Momentum Loss Rate - 2018
  • Dean Patient - 3D Printing of Stellar Magnetic Fields - 2017

Teaching Experience:

Postgraduate Teaching Assistant (2016-2020):

  • PHY2021 - Electromagnetism I
  • PHY2022 - Quantum Mechanics I
  • PHY2023 - Thermal Physics
  • PHY2024 - Condensed Matter I

Invited Seminars:

Nuggets and Press:

Attended Events:

  • UKSP Specialist Discussion Day - Presented Talk via Zoom, July 2020
  • 3rd Uk Solar Orbiter Meeting - Presented Talk at St Andrews, UK, January 2020
  • Gave a seminar to the Solar Physics group, University of Exeter, October 2019
  • Chaired the Bath, Bristol, Exeter and Cardiff Student Seminars, University of Exeter, UK, 12th October 2019
  • STFC Adv. Summer School in Solar System Plasmas, Lancaster Univeristy, UK, September 2019
  • Bcool 2019 - Presented Talk at University of Exeter, UK, July 2019
  • IAUS354: Solar and Stellar Magnetic Fields: Origins and Manifestations - Presented Poster in Copiapo, Chile, July 2019
  • ISSI Team Meeting "Solar & Stellar Wind Connection", Bern, Switzerland, June 2019
  • Evry Schatzman School "Multi-D Processes in Stellar Physics", Roscoff, France, October 2018 
  • STFC Intro. Summer School in Solar System Plasmas, University of Exeter, UK, August 2018
  • Cool Stars 20 - Presented Poster in Boston, MA, July 2018
  • Internal Seminar -  Presented talk entitled "The Effect of Magnetic Geometry on the Angular Momentum Loss From the Sun and Other Stars", University of Exeter, July 2018
  • Bcool 2018 - Presented Talk at Trinity College Dublin, April 2018
  • BBECss -  Presented talk entitled "The Effect of Magnetic Variability on the Angular Momentum Loss From the Sun and Other Stars", University of Exeter, December 2017
  • 2nd Year Talks - Presented talk entitled 'Rotational Evolution of Sun-Like Stars Due to Their Stellar Winds", University of Exeter, October 2017
  • Ages2 Conference - Presented Poster in Elba, Italy, September 2017
  • Rotation and Activity Mini Meeting - Western Washington University, WA, August 2017
  • IAUS 335: Space Weather of the Heliosphere: Processes and Forecasts - Assisted the LOC, University of Exeter, July 2017
  • Bcool 2017 - Presentation and 3D models in Montpellier, July 2017
  • National Astronomy Meeting 2017 - Presented Poster and 3D models at University of Hull, July 2017
  • Peer-Organised 1st Year Astrophysics Development Day - University of Exeter,  June 2017
  • TOUPIES Wrap-up - Meeting at Universite de Montpelier France, November 2016
  • HPC Methods for Computational Fluid Dynamics and Astrophysics - Workshop at CINECA Bologna Italy, November 2016
  • Star Formation - Conference at Exeter University, September 2016
  • Modern Observations, Theory and Techniques for Solar and Stellar Physics - Meeting at Warwick University, July 2016

Education:

PhD Physics - University of Exeter (2016-2020)

MPhys Physics with Astrophysics and Space Science - Lancaster University (2012-2016)