New England Space Science Meeting 2:

Transition from the Open to Closed Corona

Nathan Schwadron

Jan 4, 2005

Ideas

• Where are the transitions

• Do we see them with TRACE?

• Source Surface Models .. Which field lines hae opened during CMEs

• What is the connection between a region with open field and a region that appears dark in a particular band?

Welcome

• Purpose: – To facilitate interaction among colleagues in space

science in the New England Area (UNH, CfA, BU, MIT, Hanscom/AFRL, Haystack, Dartmouth)

– To leverage these interactions for initiating new, cross-disciplinary and far-reaching projects

• Meetings:– Monthly meetings (first wed each month)– Workshop?

Relationship of open and closed field topologies

• Potential field models (static)• Role of time-dependency (continuous

transitions from open to closed states?)• Conservation of open magnetic flux

– Is open flux conserved, or just preserved

• Highly sectored open fields vs structured closed fields – Open field reflects dipole term– Closed fields on much smaller scales

Relationship of solar wind and coronal heating

• Open field regions free to form steady (supersonic) flows

• Closed field regions injected energy largely lost through radiation

• Is a transition between these regimes expected?

Paths for Deposited Coronal Energy

Injected Electromagnetic

Energy

DownwardConducted Heat,

Radiation,Siphon flows

Bound

, clos

ed

struc

ture

s

Slow wind Fast wind

Open

field

Tra

nsiti

on??

Hot & Bright Cool & DarkIntermediate?Fluctuating?

Paths of deposited Energy

Schw

adro

n an

d M

cCom

as, A

pJ, 2

003

• Solar Wind Scaling Law• Electron heat

conduction and radiative losses

Fast windCool, Dark

Slow windWarm,Brighter

Radiative LossHot, Bright

von Steiger et al., JGR, 2000

Background

Well known anti-correlation between solar wind speed and freezing-in temperature, low FIP elements (Geiss et al, Science, 1995; von Steiger et al., JGR, 2000, Gloeckler, et al. 2003)

Constant Energy/particle Source

Schw

adro

n an

d M

cCom

as, A

pJ, 2

003

Flux-Flux Scaling

Constant injected energy/particle implies injected power proportional to particle flux and magnetic flux:

Injected Power proportional to magnetic flux

Injected Elec.Mag. Energy/Particle (assumed constant)

c

4dS 0

E

B Ý N

f 0 d

S 0

B 0 d

S 0

From Solar Wind to X-rays

• Solar wind power

• Yohkoh (2.8-36.6 Å)

Lx~ 1-2% Pcorona ~ 500 0 ??

Psw mu fast

2

2

GM sm

Rs

f1

B1r

0

50,0000 (cgs units)

Solar Wind to X-rays, Lx = 500 0

Pev

stov

et a

l., 2

003,

Sch

wad

ron

et a

l., 2

005

Quiet Sun

X-ray Bright Points

Active Regions

Disk Averages

G,K,M dwarfs

T-Tauri Stars

Solar Wind

X-rays over the

Solar Cycle

Sch

wad

ron

et a

l., 2

005

Power proportional To MagneticFlux

X-rays over the solar cycle

• Solar Wind Power

• GOES (1-8 Å) Active Regions: Lx~ 2.5x10-4 Pcorona

Quiet Regions: Lx~ 5x10-5 Pcorona

Coronal Holes: Lx~9x10-10 Pcorona

Psw 50,0000 (cgs units)

McC

omas

et a

l., G

RL

, 200

3

Solar wind’s high degree of organization by speed

Solar Minimum vs Solar Max