The evolution of the magnetic interaction between stars, discs, and planets

Lead Research Organisation: University of Exeter
Department Name: Physics

Abstract

Some of the most intense solar fireworks have directly affected modern life on Earth. Rapid increases in solar activity sends fluxes of charged particles towards our planet, giving rise to Aurora and disrupting satellite communications. Yet however spectacular the events on our Sun may seem today, our middle-aged star is comparatively quiet, and hides an even more violent past. A few billion years ago the Sun was a contracting ball of hot gas, although it was still too cool within its core to fuse hydrogen into helium and shine as it does today. Young solar analogues, called T Tauri stars, are about a million times too faint to be seen with the naked eye. Space satellite observations, however, have shown that they are typically 1000 times more active in X-rays than the Sun is presently. They are surrounded by large dusty planet-forming discs, which are bombarded by X-rays arising from violent stellar magnetic events. T Tauri stars are new-born stars which are still shrinking down under gravity to their adult proportions. As such stars collapse they should start to spin faster and faster, just like an ice-skater who pulls their arms in closer to their body. However, such stars are observed to be spinning slowly, an effect that has been attributed to how their strong magnetic fields interact with the gas and dust within their planet-forming discs. T Tauri stars are embedded in a web of magnetic field which binds them to the gas and dust within the disc. It is expected that this magnetic web acts as a brake, allowing the star to remain spinning slowly. This process, however, is poorly understood. Using a technique called Zeeman-Doppler imaging I have been able to determine the structure of their magnetic webs. This technique has strong parallels to the tomographic methods applied to construct 3D images of internal organs of the human body. This newly available data signals the beginning of a fresh era of research in to the formation of solar-like stars. My research will exploit this new stream of data, to investigate how forming stars interact with, and disrupt, their circumstellar environments. Ultimately this work will provide insight into the formation of our own Sun, and Solar System, at a time when the planets were just beginning to form. Roughly 300 planets have now been found orbiting other stars. It recently been discovered that some of these stars twinkle on the same timescale as it takes their planets to complete an orbit. This effect may be caused by highly energetic particles crashing into the stellar surface after being accelerated along strands of the magnetic web connecting the planet to the star. I will investigate this process in detail during the STFC fellowship.

Publications

10 25 50

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Donati J (2010) Complex magnetic topology and strong differential rotation on the low-mass T Tauri star V2247 Oph in Monthly Notices of the Royal Astronomical Society

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Flaccomio, Ettore (2011) Coordinated Optical/X-ray observations of the CTTS V2129 Oph The Chandra View in Astronomical Society of the Pacific Conference Series

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Walter, Fred (2011) Surface and Atmospheric Structure on the T Tauri Star V2129 Oph in Astronomical Society of the Pacific Conference Series

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Gregory S (2010) The magnetic fields of forming solar-like stars in Reports on Progress in Physics

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Johnstone C (2012) The soft X-ray light curves of partially eclipsed stellar flares Eclipsing of stellar flares in Monthly Notices of the Royal Astronomical Society

 
Description STFC received a FINAL REPORT on this grant in 2010.
Exploitation Route STFC received a FINAL REPORT on this grant in 2010.
Sectors Education,Other

 
Description STFC received a FINAL REPORT on this grant in 2010.
 
Description DAOofTau (Disks, Accretion, and Outflows of T Tauri stars) 
Organisation California Institute of Technology
Country United States 
Sector Academic/University 
PI Contribution Theoretical interpretation of Hubble Space Telescope, and associated ground based, data.
Collaborator Contribution Project leadership. Data analysis and observing program coordination.
Impact Two conference proceedings and 3 journal papers. NB: I am only counting publications for which my contributions were made when I was funded from STFC grants. There are multiple other publications associated with this project. NASA ADS bibliography codes: 2013ApJ...767..112I, 2013ApJS..207.1A, 2013ApJ...767..112I, 2013AAS22111704A, 2010HEAD11.1709B.
Start Year 2008
 
Description DAOofTau (Disks, Accretion, and Outflows of T Tauri stars) 
Organisation Peking University
Country China 
Sector Academic/University 
PI Contribution Theoretical interpretation of Hubble Space Telescope, and associated ground based, data.
Collaborator Contribution Project leadership. Data analysis and observing program coordination.
Impact Two conference proceedings and 3 journal papers. NB: I am only counting publications for which my contributions were made when I was funded from STFC grants. There are multiple other publications associated with this project. NASA ADS bibliography codes: 2013ApJ...767..112I, 2013ApJS..207.1A, 2013ApJ...767..112I, 2013AAS22111704A, 2010HEAD11.1709B.
Start Year 2008
 
Description DAOofTau (Disks, Accretion, and Outflows of T Tauri stars) 
Organisation University of Colorado Boulder
Country United States 
Sector Academic/University 
PI Contribution Theoretical interpretation of Hubble Space Telescope, and associated ground based, data.
Collaborator Contribution Project leadership. Data analysis and observing program coordination.
Impact Two conference proceedings and 3 journal papers. NB: I am only counting publications for which my contributions were made when I was funded from STFC grants. There are multiple other publications associated with this project. NASA ADS bibliography codes: 2013ApJ...767..112I, 2013ApJS..207.1A, 2013ApJ...767..112I, 2013AAS22111704A, 2010HEAD11.1709B.
Start Year 2008
 
Description MaPP (Magnetic Protostars and Planets) program 
Organisation Paul Sabatier University (University of Toulouse III)
Country France 
Sector Academic/University 
PI Contribution I am the lead theory CoI in the program. Theoretical interpretation of the data, and construction of numerical models.
Collaborator Contribution Project leadership. Data analysis and observing program coordination.
Impact 4 conference paper, and 5 journal papers. NB: I am only counting publications for which my contributions were made when I was funded from STFC PI grants. There are multiple other publications associated with the project. NASA ADS bibliography codes: 2010MNRAS.402.1426D, 2010MNRAS.409.1347D, 2013MNRAS.436..881D, 2014MNRAS.437.3202J, 2014MNRAS.441.2361V, 2014IAUS..30240G, 2014IAUS..30244G, 2014EPJWC..6408009G, 2015IAUGA..2232877V.
Start Year 2008
 
Description V2129 Oph multi-wavelength observing program 
Organisation European Southern Observatory (ESO)
Country Germany 
Sector Charity/Non Profit 
PI Contribution I set up the collaboration and then was involved in the theoretical modelling of the data.
Collaborator Contribution Data analysis and observing program coordination.
Impact 3 conference proceedings and 2 journal papers. My biggest contributions were made while funded from STFC PI grants, although some were published while funded from other sources / working outside of the UK. NASA ADS bibliography codes: 2011A&A...530A1A, 2011MNRAS.412.2454D, 2011ASPC..448..755W, 2011ASPC..448..603F, 2009hrxs.confE..17G.
Start Year 2008
 
Description V2129 Oph multi-wavelength observing program 
Organisation Observatory of Grenoble
Country France 
Sector Academic/University 
PI Contribution I set up the collaboration and then was involved in the theoretical modelling of the data.
Collaborator Contribution Data analysis and observing program coordination.
Impact 3 conference proceedings and 2 journal papers. My biggest contributions were made while funded from STFC PI grants, although some were published while funded from other sources / working outside of the UK. NASA ADS bibliography codes: 2011A&A...530A1A, 2011MNRAS.412.2454D, 2011ASPC..448..755W, 2011ASPC..448..603F, 2009hrxs.confE..17G.
Start Year 2008
 
Description V2129 Oph multi-wavelength observing program 
Organisation Paul Sabatier University (University of Toulouse III)
Country France 
Sector Academic/University 
PI Contribution I set up the collaboration and then was involved in the theoretical modelling of the data.
Collaborator Contribution Data analysis and observing program coordination.
Impact 3 conference proceedings and 2 journal papers. My biggest contributions were made while funded from STFC PI grants, although some were published while funded from other sources / working outside of the UK. NASA ADS bibliography codes: 2011A&A...530A1A, 2011MNRAS.412.2454D, 2011ASPC..448..755W, 2011ASPC..448..603F, 2009hrxs.confE..17G.
Start Year 2008
 
Description V2129 Oph multi-wavelength observing program 
Organisation University at Buffalo
Country United States 
Sector Academic/University 
PI Contribution I set up the collaboration and then was involved in the theoretical modelling of the data.
Collaborator Contribution Data analysis and observing program coordination.
Impact 3 conference proceedings and 2 journal papers. My biggest contributions were made while funded from STFC PI grants, although some were published while funded from other sources / working outside of the UK. NASA ADS bibliography codes: 2011A&A...530A1A, 2011MNRAS.412.2454D, 2011ASPC..448..755W, 2011ASPC..448..603F, 2009hrxs.confE..17G.
Start Year 2008
 
Description V2129 Oph multi-wavelength observing program 
Organisation University of Palermo
Country Italy 
Sector Academic/University 
PI Contribution I set up the collaboration and then was involved in the theoretical modelling of the data.
Collaborator Contribution Data analysis and observing program coordination.
Impact 3 conference proceedings and 2 journal papers. My biggest contributions were made while funded from STFC PI grants, although some were published while funded from other sources / working outside of the UK. NASA ADS bibliography codes: 2011A&A...530A1A, 2011MNRAS.412.2454D, 2011ASPC..448..755W, 2011ASPC..448..603F, 2009hrxs.confE..17G.
Start Year 2008
 
Description Exeter astronomy open day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Talked with members of the public about astronomical research at Exeter, and answered general astronomy questions.

Increased public awareness of UK astronomy research, and in particular the ongoing work at the University of Exeter.
Year(s) Of Engagement Activity 2010