1 / 16

Modelling X-ray Bright Points on the Quiet Sun.

Modelling X-ray Bright Points on the Quiet Sun. Parameter fitting to a Coronal Heating solution. Matthew Chantry. University of St Andrews. Mentor: Aad van Ballegooijen. Modelling X-ray Bright Points on the Quiet Sun. What is an X-ray Bright point?.

reya
Download Presentation

Modelling X-ray Bright Points on the Quiet Sun.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Modelling X-ray Bright Points on the Quiet Sun. Parameter fitting to a Coronal Heating solution. Matthew Chantry University of St Andrews Mentor: Aad van Ballegooijen

  2. Modelling X-ray Bright Points on the Quiet Sun. What is an X-ray Bright point? • X-ray bright points are small dynamic loop structures that are observed all over the solar corona. • They have a correspondence with small bipolar magnetic regions (Krieger et al. 1971, Tousey et al. 1973). Matthew Chantry University of St Andrews REU Symposium

  3. Modelling X-ray Bright Points on the Quiet Sun. Aim • To find coronal heating parameters that enable modelling of XRT intensities in multiple filters. Method • Construct a potential field from a magnetogram. • Solve the energy equation for each field line. • Compute XRT intensities. • Compare to XRT data. Matthew Chantry University of St Andrews REU Symposium

  4. Modelling X-ray Bright Points on the Quiet Sun. Construct Potential field Line of sight Matthew Chantry University of St Andrews REU Symposium

  5. Modelling X-ray Bright Points on the Quiet Sun. Coronal Heating rate per unit volume (van Ballegooijen 1986) Bphoto – 1500G, field strength in the photospheric network (Stenflo1984). Bmag – the magnetic field strength at each point along the field line. f – filling factor, the heat is not applied evenly along the LOS, but is applied to a proportion of each part of the LOS. LT – the total length of the field line Lp & τ – variables which describe the length and time scales of the granulations which input the energy into the system. f& Lp are the unknown variables which make up our parameter space. Matthew Chantry University of St Andrews REU Symposium

  6. Modelling X-ray Bright Points on the Quiet Sun. Solving the Energy Equation Field line Temperature Temperature Density Density Line of sight Matthew Chantry University of St Andrews REU Symposium

  7. Modelling X-ray Bright Points on the Quiet Sun. Field line Computing XRT Intensities Line of sight Matthew Chantry University of St Andrews REU Symposium

  8. Modelling X-ray Bright Points on the Quiet Sun. Comparing to XRT data Ti-poly Bp 1 Model: Full line Data: Dashed line Matthew Chantry University of St Andrews REU Symposium

  9. Modelling X-ray Bright Points on the Quiet Sun. Measuring the fit Bp 1 Ti-poly Al-poly/Ti-poly C-poly/Ti-poly C-poly Matthew Chantry University of St Andrews REU Symposium

  10. Modelling X-ray Bright Points on the Quiet Sun. Combined fit Bp 1 Minimum Matthew Chantry University of St Andrews REU Symposium

  11. Modelling X-ray Bright Points on the Quiet Sun. Fitting the Temperature Ti-poly Bp 1 Matthew Chantry University of St Andrews REU Symposium

  12. Modelling X-ray Bright Points on the Quiet Sun. Fitting the Temperature Be-thin Bp 1 Matthew Chantry University of St Andrews REU Symposium

  13. Modelling X-ray Bright Points on the Quiet Sun. Fitting the Temperature Ti-poly Bp 1 Matthew Chantry University of St Andrews REU Symposium

  14. Modelling X-ray Bright Points on the Quiet Sun. Intensities in other filters Al-poly/Ti-poly C-poly/Ti-poly Bp 1 Bp 1 C-poly Be-thin Bp 1 Bp 1 Matthew Chantry University of St Andrews REU Symposium

  15. Modelling X-ray Bright Points on the Quiet Sun. Errors • Using this XRT data, we cannot uniquely determine the filling factor. Need longer exposures in thicker filters? • Other sources of error/uncertainty: • Alignment of XRT images to the magnetogram. • Calibration of XRT intensities. • Unclear what the statistical errors are. • XRT response rates. • Heating model is time averaged, but bright point intensities oscillate (Kariyappa & Varghese 2008). • Plasma beta > 1 for low filling factors. Matthew Chantry University of St Andrews REU Symposium

  16. Modelling X-ray Bright Points on the Quiet Sun. Conclusions • For this bright point a good fit can be achieved for all 5 filters. • This method has also been successfully applied to other bright points (in this and other data-sets). • Fits are not always found for more complicated magnetic structures. • Systematic difference found at the sides of the features. • Work with density sensitive line ratios has found bright point filling factors < 0.1 (Dere 2008 & 2009). Thanks to Aad van Ballegooijen, Steve Saar, Henry (Trae) Winter III, Kelly Koreck and everyone else! Matthew Chantry University of St Andrews REU Symposium

More Related