The Halo CMEs Speeds and Energy of Their Related Active Regions

1
The Halo CMEs Speeds and Energy of Their Related
Active Regions

• Yang Liu¹, and CDAW Source Identification Team²
• ¹Stanford University
• ² Including E. Cliver, N. Gopalswamy, J. Kasper,
  N. Nitta, I. Richardson, B. Thompson, D. Webb, C.
  Wu, S. Yashiro, J. Zhang, A. Zhukov, etc.

2
Motivations

• CMEs and active regions (large-scale and local
  fields)
• Observation has shown some CMEs are associated
  with solar flares in active regions
• Studies further demonstrate correlation between
  the soft X-ray flux of flares and the speeds of
  the CMEs (Moon et al. 2002 Zhang et al. 2004)
  and also show relationship of the inferred
  magnetic reconnection rate and the acceleration
  of the CMEs (Qiu et al. 2004)
• It is generally believed that the energy released
  during the events is primarily the free energy
  stored in the magnetic field in the corona.
• Thus, it is reasonable to search for relationship
  between the magnetic energy of active regions and
  the related CMEs energy.

3
Purpose of this work

• We are seeking for indexes from magnetograms that
  can describe the energy of solar active regions,
  and also seeking for possible correlation between
  the indexes and the related CMEs speeds
• We are seeking for advancing our understanding on
  underlying link between the local field of active
  regions and global phenomenon of CMEs.

4
Energy indexes of active regions
From Fisher et al (2000)

• Potential field energy of active regions.
• Free energy of active regions
• (assuming single flux tube).
• Index of free energy (single flux tube).

Where L is self-inductance and I is electric
current that can be computed assuming the field
is force free. But we need to estimate force-free
alpha.
Two parameters to be calculated tilt angle, and
force free alpha (alpha).
5
Samples

• We choose events from CDAW (Coordinate Data
  Analysis Workshop held in 2005) event list based
  on two criteria
• Halo-CMEs
• Solar source is associated with active regions.

6
List of the events
7
Potential field energy versus CMEs speeds

• No correlation is found.

8
Properties of active regions versus CMEs speeds

• No correlation was found between sizes of active
  regions and CMEs speeds
• No correlation was found between net flux of
  active regions and CMEs speeds.

9
Free energy in active regions versus CMEs speeds

• Weak correlation was found between E_free/length
  and CMEs speed.

10
Energy index of active regions versus CMEs
speeds

• Weak correlation was found between the parameter
  eE_potential and CMEs speed.

11
Summary

• Potential field energy of active regions versus
  CMEs speed NO CORRELATION.
• Free energy of active regions versus CMEs speed
  WEAK CORRELATION.
• Index of free energy of active regions versus
  CMEs speed WEAK CORRELATION.

12
Conclusions

• We have examined here two measures of free energy
  of solar active regions we found weak
  correlations between such measures and related
  halo CMEs speed
• These correlations imply that, although magnetic
  field of active regions is localized and a CME is
  a global phenomenon, active regions make a
  significant contribution in energizing the active
  region-associated CMEs. It suggests again, from
  energy perspective of active regions and CMEs,
  that local and global fields are coupled each
  other.

13
Free energy of active regions versus CMEs
kinetic energy

• No correlation was found between total free
  energy of active regions and CMEs kinetic
  energy
• No correlation was found between proxy of total
  energy (eE_potential) of active regions and
  CMEs kinetic energy.