Investigating solar Lx-B relation: with Hinode/XRT and SDO/HMI.


Nathaniel Cohen (California State Univ.) with Aki Takeda
as a MSU solar/space REU 2026 project.

Project description

Our Sun is a G type star with the surface temperature at around 6000(K), but its thin atmosphere called corona is known to be more than 300 times hotter than the surface. The heating mechanism of the corona above the cooler surface is not fully understood, but the magnetic flux penetrating the surface from Sun's interior is believed to play a crucial role. This project explores the possible heating mechanism by closely comparing the coronal X-ray luminocity (Lx: measured as soft X-ray intensity) with the photospheric line-of-sight magnetic field (B: obtained from spectral information of visible light).

We will use data acquired in space. As soft X-ray data, we will use X-Ray Telescope(XRT) aboard the Hinode satellite (an international mission among Japan/US/UK), As magnetic field data we will use Helioseismic and Magnetic Imager(HMI) aboard the Solar Dynamic Observatory (a NASA mission). Student will first learn about these instruments and basic calibration of the data. The data analysis will be performed using IDL (Interactive Data Language) software. Experience with IDL programming would be favorable, but not required, as the basic programs will be provided.

This REU project started in 2024 as an extension of the study described in Yoshimura et al (2025) , which uses the full-Sun integrated signals of soft X-ray and magnetic field images. In the past two years, Lx-B relation for the sunspots was investiaged. This year, this project will further expand the object of research to other solar structures like coronal bright points and quiet Sun.

Weekly goals

  • Week 1 (5/26 -- 5/29) :
    • attend Python and IDL tutorials.
    • background study (flare class, GOES, solar coordinates, etc.)
    • lend out "Encyclopedia of the Sun".
  • Week 2 (6/1 -- 6/5) :
    • Study of the instruments: Hinode/XRT and SDO/HMI.
    • Preparation for the short presentation on Friday 2pm.
  • Week 3 (6/8 -- 6/12) :
    • Data selection (select dates from SCIA).
    • Understand image co-alignment (XRT & HMI).
    • Pick up XRT bright points and corresponding HMI structures.
    • How to prepare personal web site (uploading the presentation file).
  • Week 4 (6/15 -- 6/19) :
    • XRT intensity readings of selected bright points with two filters (Al_mesh and Al_poly).
    • Preparation for the group meeting on Friday 2pm.
  • Week 5 (6/22 -- 6/26) :
    • Nathaniel's last year's REU experience at Prinston Center for Complex Materials.
    • Conversion of intensity to Te and EM.
    • Preparation of AAS/SPD meeting attendance (8/10-14 in MD).
      • create an account on the SPD meeting site
      • searching for available flights to/from MD
  • Week 6 (6/29 -- 7/3) :
    • Preparation of mid-term presentaion: supporting plots of filter ratio method
      [memo: created by xrt_resp/get_fratio_amap_ch1102.pro]
    • Mid-term comment: Histogram study for BPs would be useful (by Dana).
  • Week 7 (7/6 -- 7/10) :
    • Add more data from the period around solar minimum.
      • 2017/12/29 (by Nathaniel)
      • 2020/02/12 (by Nathaniel)
      • 2021/01/08 (by Nathaniel)
      • 2018/07/09 (by Aki)
      • 2019/05/19 (by Aki)
      • 2020/05/13 (by Aki)
  • Week 8 (7/13 -- 7/17) :
    • To get more data points for a wider range of QS, apply larger or smaller FOV size to solar minimum data.
    • Try linear fitting of BP and QS data points (poly_fit)
    • Make histogram for Te, EM and Luminocity.
    • Plot with error bars.
    • Prepare for the group meeting presentation.
  • Week 9 (7/20 -- 7/24) :
  • Week 10 (7/27 -- 7/31) :

Resources