NRO

Report

No. 479

Proceedings of the Nobeyama Symposium

Kiyosato, Japan, Oct. 27-30, 1998

Edited by

T. Bastian, N. Gopalswamy and K. Shibasaki

December 1999

ISSN 0911-5501

Radio observations contribute a unique perspective on the many physical phenomena, which occur on the Sun. From thermal bremsstrahlung emission in the quiet solar atmosphere and filaments, to thermal gyroresonance emission in strongly magnetized solar active regions, to the nonthermal emission from MeV electrons accelerated in flares, observations of radio emission provide a powerful probe of physical conditions on the Sun and provide an additional means of understanding the myriad phenomena which occur there. Moreover, radio observing techniques have led the way in developing and exploiting Fourier synthesis imaging techniques. The Nobeyama Radioheliograph, commissioned in June, 1992, soon after the launch of Yohkoh satellite in August, 1991, is the most powerful, solar-dedicated Fourier synthesis in the world, now capable of imaging the full disk of the Sun simultaneously at frequencies of 17 and 34 GHz, with an angular resolution as much as 10" and 5", respectively, and with a time resolution as fine as 100 msec.

Between 27-30 October, 1998, the Nobeyama Radio Observatory and the National Astronomical Observatory of Japan hosted the Nobeyama Symposium on Solar Physics with Radio Observations, an international meeting bringing more than sixty participants together at the Seisenryo Hotel in Kiyosato, for a meeting devoted to reviewing recent progress in outstanding problems in solar physics. Emphasis was placed on radio observations and, in particular, radio observations from the very successful Nobeyama Radioheliograph. These results were compared and contrasted with those that have emerged from the Yohkoh mission. In addition, looking forward to the next solar maximum, new instruments, upgrades, and collaborative efforts were discussed. The result is the more than seventy invited and contributed papers that appear in this volume.

We thank the members of the Scientific Organizing Committee for their thoughtful assistance in organizing a timely, interesting, and at times provocative meeting. We extend warm thanks to the Local Organizing Committee for organizing a meeting at so beautiful a venue and for providing all of the behind-the-scenes support so critical to the success of the meeting. We thank Dr. Yokoyama for his extensive work to realize this volume. Finally, we thank the sponsoring agencies of this meeting, the Nobeyama Radio Observatory and the National Astronomical Observatory of Japan.

T. Bastian

N. Gopalswamy

K. Shibasaki

Preface ………………………………………………………………………….… i

Contents ……………………………………………………………………………. iii

Program …………………………………………………………………………….. ix

Microwave Observations of the Quiet Sun

K. Shibasaki………………………………………………………………..1

Low Frequency Observations of the Quiet Sun: a Review

P. Lantos……………………………………………………………………11

Heating Events in the Quiet Solar Corona

S. Krucker and A.O. Benz……………………………………………….25

Radio Bright Structures near the Solar Poles at Millimeter Wavelengths

S. Pohjolainen, F. Portier-Fozzani and D. Ragaigne………………...31

Radio Observations of Filaments at the SSRT

V. G. Zandanov and S.V. Lesovoi……………………………………….37

Physics of the Solar Active Regions from Radio Observations

G.B. Gelfreikh ……………………………………………………………41

Magnetic Field Diagnostics in the Low Corona from Microwave Circular Polarization Inversion

C.E. Alissandrakis………………………………………………………..53

Microwave Measurements of the Solar Magnetic Fields at Chromosphere-Corona

A. Grebinskij, K. Shibasaki and H. Zhang……………………………59

Active Region Emissions and Coronal Field Extrapolations

J. Lee, S. M. White, M. R. Kundu and Z. Mikic ……………………..65

RATAN-600 Observations of Solar Cyclotron Lines and their Interpretation

V. Bogod, V. Garaimov, V. Zheleznyakov and E. Zlotnik ……………71

Magnetic Separatrix and Coronal Loop Heating in an Active Region

T. Sakurai and H. Wang………………………………………………….77

17 GHz Mode Coupling in the Solar Corona

A. Lara, N. Gopalswamy, R. Perez-Enriquez and K. Shibasaki……83

Evolution of Active Regions in Microwave Emission at the Stage of Their Initiation

D.Yu. Myachin, V. P.Nefedyev, A.M. Uralov, S. V. Lesovoi and

G. Ya. Smolkov…………………………………………………………….89

Magnetic Neutral Line-Associated Radio Sources and Evolution of the Active Region NOAA 7321

A. M. Uralov, H. Nakajima, V. G. Zandanov, and V. V. Grechnev ..93

Thermal Evolution of Coronal Active Regions

S. Yashiro, K. Shibata and M. Shimojo……………………………….99

Temperature Structure of Non-Flaring Loops

N. Nitta…………………………………………………………………..103

Distribution of Photospheric Current Helicity

8. H. Zhang and S. Bao…………………………………………………………107

Radio Observations of Weak Coronal Transients

M.R. Kundu …………………………………………………..…………111

Weak Transient Activities in the Corona

T. Shimizu……………………………………………………….………123

Radio Counterparts to SXR Transients

D.E. Gary………………………………………………………………...129

A Microwave Study of Coronal and Chromospheric Ejecta

1. Nindos, M. R. Kundu, J. -P. Raulin, K. Shibasaki, S. M. White,

X-ray and Microwave Signatures of Coronal Mass Ejections

N. Gopalswamy…………………………………………………………141

Long Duration Events Observed with the Nobeyama Radioheliograph

Y. Hanaoka………………………………………………………………153

Coronal Mass Ejections at High Temperatures

H. Hudson………………………………………………………………..159

Multi-Wavelength Observations of a Large-Scale Jet and an Eruptive-Prominence on 28 August 1992

Ta. Watanabe, K. Ashizawa, Y. Nakagawa, H. Miyazaki, M. Irie,

K. Ichimoto, H. Kurokawa, H. Hudson and H. Yatagai…………..171

Large-Scale Shining Chains on the Solar Disk: Nobeyama Radioheliograph Data

I. M. Chertok and K. Shibasaki………………………………………175

Large-Scale Shining Chains on the Solar Disk: Yohkoh/SXT, SOHO/EIT and TRACE data

I. M. Chertok…………………………………………………………….181

Radio and Coronagraph Observations: Shocks, Coronal Mass Ejections and Particle Acceleration

M. Pick……………………………………………………………………187

Geomagnetic Disturbances Around the Solar Minimum of Cycle 22 and Their Solar Sources

S. Watari and Ta. Watanabe…………………………………………...199

Nobeyama Radioheliograph Data on Dynamics of Microwave Counterparts of Giant Post-Eruptive Soft X-ray Arches

1. M. Chertok, V. V. Fomichev, R. V. Gorgutsa, J. Hildebrandt,

Multi-wavelength Signatures of Coronal Mass Ejection

N. Gopalswamy, S. Yashiro, M. L. Kaiser, B. J. Thompson and S. Plunkett…...207

Impulsive Flares: A Microwave Perspective

T. S. Bastian……………………………………………………………...211

Millimeter Interferometer Observations of Flares

S.M. White………………………………………………………………..223

Radio and X-ray Observations of the Flares Caused by Interacting Loops

Y. Hanaoka……………………………………………………………….229

Nobeyama/HXT Observations of Impulsive Flares

M. Nishio, T. Kosugi, K. Yaji and H. Nakajima…………………….235

Thermal and Nonthermal Components in an X-Class Long Duration Flare

H. Nakajima, J. Sato and K. Fujiki…………………………………..243

17 and 34 GHz Observations of the Sun with The Nobeyama

Radioheliograph

K. Fujiki…………………………………………………………………..249

Comparison of Microwave and HXR Spectra from Solar Flares

A.V. R. Silva, H. Wang and D. E. Gary……………………………….255

Intensity Fluctuations of Solar Radio Emission, Scattered by Coronal Turbulence

A.M. Uralov………………………………………………………………261

Fast Temporal Variations of the Circular Polarization Degree During a Microwave Solar Burst

E. Correia, P. Kaufmann and V. Melnikov…………………………..263

Study of Solar Decimetric Bursts with a Pair of Cutoff Frequencies

K. Hori………………………………………………………………….…267

Temporal and Spatial Evolution of Microwave Spikes by Beijing and Nobeyama Observatories

Q. Fu, G. Huang, K. Shibasaki, H. Nakajima and Y. Liu…………273

Microwave Observations of Sub-second Pulses with Spatial Resolution

A. Altyntsev, H. Nakajima, T. Takano, V. Grechnev and S. Konovalov…………..279

The Study of Solar Flares with Microwave Sub-second Pulses at 5.7 and 17 GHz

1. Altyntsev, V. Grechnev, H. Nakajima, Y. Hanaoka,
2. S., Konovalov and T. Takano……………………………………….283

Spatial and Temporal Evolution of Magnetic Loops on April 15, 1998

G. L. Huang and Q. Fu

On Some New Results of Broadband Meter / Decimeter Observations

H. Aurass…………………………………………………………………293

Radio and Hard X-ray Observations of Flares and their Physical Interpretation

M. Aschwanden………………………………………………………….307

HXT Observations of Solar Flares - A Review and Perspective -

T. Sakao…………………………………………………………………...321

Energetic (HXR/GR) Emission from Flares: Implications for Particle Acceleration and Transport

N. Vilmer………………………………………………………………….335

Flare Loop Geometry

N. Nitta…………………………………………………………………...343

Observation of the Loop-Top Source of the 1998 April 23 Flare

J. Sato and Y. Hanaoka…………………………………………………349

Two Types of Gamma-Ray Flares

M. Yoshimori, A. Shiozawa and K. Suga…………………………….353

Models for Flare Statistics and the Waiting-time Distribution of Solar Flare Hard X-ray Bursts

M. S. Wheatland and S. D. Edney……………………………………357

Nonthermal Electrons Accelerated in Solar Flare Loops

K. Yaji……………………………………………………………………..361

X-ray Plasma Ejection Associated with H-alpha Filament Eruption

M. Ohyama and K. Shibata……………………………………………367

Flare Models and Radio Emission

D. B. Melrose…………………………………………………………..…371

Reconnection Models of Flares

K. Shibata…………………………………………………………….…..381

MHD Simulations of Flares

T. Yokoyama ..………………………………………………………...… 391

Evidence Supporting Quadruple Magnetic Source Model of Arcade Flarings, and Implications

Y. Uchida, S. Morita, M. Torii, K. Fujisaki, S. Hirose and

T. Yamaguchi …………………………………………………………….397

Numerical Magnetohydrodynamic Model of Dark Filament Eruption and Arcade Flaring

S. Hirose, Y. Uchida, S. B. Cable, S. Uemura and T. Yamaguchi…403

Current-Injection Model for Loop Flares and Active Region Transient Loop Brightenings

T. Miyagoshi, T. Yabiku, Y. Uchida and S. Hirose ………………… 407

Derivation of the 3D Structure of Flares in the Homologous Flare Series of 1992 February

S. Morita, Y. Uchida, S. Hirose, S. Uemura and T. Yamaguchi … 413

Observational Evidence of Ballooning Instabilities in a Solar Flare

K. Shibasaki ……………………………………………………………. 419

The SSRT in the 23^rd Cycle of Solar Activity

V. G. Zandanov, A. T. Altyntsev and S. V. Lesovoi ………………… 425

OVRO Solar Array Upgrades in Preparation for MAX 2000

D. E. Gary and G. J. Hurford ………………………………………… 429

A Broadband Radiospectrometer and Fine Structures in Microwave bursts

Q. Fu, Y. Liu, H. Ji, C. Cheng, Z. Cheng, D. Lao, Z. Qin, G. Yang,

L. Pei, G. Huang, H. Wu, Q. Yao, Z. Xia and R. Xie ......... 433

Progress Report of the New Solar Submm-Wave Telescope (SST) Installation

P. Kaufman, A. Magun, H. Levato, M. Rovira, K. Arzner, E. Correia,

J. E. R. Costa, C. G. Gimenez de Castro, N. Kampfer, J.-P. Raulin,

E. Rolli and A. V. R. Silva ………………………………………………... 439

Development of New Solar Optical Observation Systems at Mitaka, NAOJ

Y. Suematsu ……………………………………………………………. 443

The Astronomical Low Frequency Array (ALFA): Imaging from Space

N. Gopalswamy, M. L. Kaiser D. L. Jones, M.L.

and The ALFA Team …………………………………………………… 447

Solar Max 2000: Scientific Objectives and Coordinated Observation

T. Kosugi ………………………………………………………………... 453

T. Shimizu and The Solar-B Working Group ...............457

List of Participants ………………………………………………………………471

9:00 - 9:20 OPENING ADDRESSES

9:20 - 10:00 K. Shibasaki:

Microwave Observations of the Quiet Sun

10:00 - 10:40 P. Lantos:

Low Frequency Observations of the Quiet Sun

10:40 - 11:00 (Break)

11:00 - 11:20 S. Krucker and A.O. Benz:

11:20 - 11:40 S. Pohjolainen, F. Portier-Fozzani and D. Ragaigne:

11:40 - 11:45 Poster Presentation and Discussion

V. Zandanov and S. Lesovoi

Filament Observations at the SSRT

11:45 - 12:25 G.B. Gelfreikh :

Physics of the Solar Active Regions from Radio Observations

12:25 - 12:45 C.E. Alissandrakis :

12:45 - 14:00 (Lunch Break)

14:00 - 14:20 A.S. Grebinskij :

14:20 - 14:40 J. Lee :

Active Region Emission and Coronal Field Extrapolation

14:40 - 15:00 V. Bogod, V. Garaimov, V. Zheleznyakov and E. Zlotnik :

RATAN-600 Observations of Solar Cyclotron Lines and their Interpretation

15:00 - 15:20 T. Sakurai and H.N. Wang:

Quasi-Separatrix Layers and Coronal Loop Heating in an Active Region

15:20 - 15:50 Poster Presentation and Discussion

A. Lara, N. Gopalswamy and K. Shibasaki

Microwave Observations of Mode Coupling in Solar Active Regions

D.Yu. Myachin et al.

Evolution of Active Regions in Microwave Emission at the Stage of Their

Initiation

A. Uralov, H. Nakajima, V. Zandanov, and V.Grechnev

Behavior of Neutral Line Associated Source at 17 GHz and Deduced Spatial

Model

S. Yashiro, K. Shibata and M. Shimojo

Thermal Evolution of Coronal Active Regions

N. Nitta

Temperature Structure of Non-Flaring Loops

H. Zhang

Magnetic Helicity and Solar Activity Cycle

15:50 - 16:10 (Break)

16:10 - 16:50 M.R. Kundu :

Radio Observations of Weak Solar Transients: A Review

16:50 - 17:10 T. Shimizu :

Soft X-ray Transient Activities in the Corona

17:10 - 17:30 D.E. Gary:

Radio Counterparts to SXR Transients

17:30 - 17:50 A. Nindos et al:

A Microwave Study of Coronal and Chromospheric Ejecta

17:50 - 17:55 Poster Presentation and Discussion

K. Hori

Study of Microwave Blobs above a Top of Arcade Loops in the Solar Corona

9:00 - 09:40 N. Gopalswamy:

Microwave and X-ray Signatures of Coronal Mass Ejections

9:40 - 10:00 Y. Hanaoka:

Long Duration Events Observed with the Nobeyama Radioheliograph

10:00 - 10:30 H. Hudson:

Coronal Mass Ejections at High Temperatures

10:30 - 10:50 Ta. Watanabe et al.:

10:50 - 11:10 (Break)

11:10 - 11:30 I.M. Chertok:

Large-Scale Shining Chains on the Solar Disk

11:30 - 12:10 M. Pick:

Review of Meter Wavelength and Coronagraph Observations

12:10 - 12:30 Poster Presentation and Discussion

S. Watari and Ta. Watanabe

Geomagnetic Disturbances Around the Solar Minimum of Cycle 22 and Their

Solar Sources

I.M. Chertok et al.

Nobeyama Radioheliograph Data on Dynamics of Microwave Counterparts of

Giant Post-Eruptive Soft X-ray Arches

Afternoon - (Excursion + Get-together Party)

09:00 - 09:40 T. Bastian:

Impulsive Flares: A Microwave Perspective

09:40 - 10:00 S.M. White:

Recent Progress in Millimeter Observations

10:00 - 10:20 Y. Hanaoka:

10:20 - 10:40 M. Nishio et al.:

Nobeyama/HXT Observations of Impulsive Flares

10:40 - 11:00 (Break)

11:00 - 11:20 H. Nakajima et al.:

11:20 - 11:40 K. Fujiki:

Nobeyama 17/34 GHz Observations

11:40 - 12:00 A.V.R. Silva, H. Wang and D.E. Gary:

Comparison of Microwave and HXR Spectra from Solar Flares

12:00 - 12:20 A.M. Uralov:

Scintillation of Solar Radio Sources: Implications for Spikes

12:20 - 13:00 Poster Presentation and Discussion

E. Correia and P. Kaufmann

Temporal Behaviour of the Circular Polarization of Solar Bursts at 7 GHz

K. Hori

Study of Solar Decimetric Bursts with A Pair of Cutoff-Frequency Drifts

D.Yu. Myachin and G.Ya. Smolkov

Q. Fu et al.

A. Altyntsev et al.

Microwave observations of sub-second pulses with spatial resolution

A. Altyntsev et al.

GHz

G. Huang and Q. Fu

Spatial and Temporal Evolution of Magnetic Loops on April 14, 1998

14:00 - 14:40 H. Aurass:

14:40 - 15:20 M. Aschwanden:

Radio and HXR Observations and their Interpretation

15:20 - 15:40 J.-P. Raulin et al.:

Time and Space Distibution of Discree Energetic Releases in Millimeter-wave

Solar Bursts

15:40 - 16:00 (Break)

16:00 - 16:40 S. Tsuneta:

SXT Observations of Flares

16:40 - 17:20 T. Sakao:

HXT Observations of Solar Flares - A Review and Perspective -

17:20 - 17:40 N. Vilmer:

Energetic (gamma-ray) Emission from Flares: Implications for Particle

Acceleration and Transport

17:40 - 18:15 Poster Presentation and Discussion

N. Nitta

Flare Loop Geometry

J. Sato and Y. Hanaoka

Observation of Loop-Top Sources on 23 April 1998 Flare

M. Yoshimori, A. Shiozawa and K. Suga

Two Types of Gamma-Ray Flares

M.S. Wheatland and S.D. Edney

Models for Flare Statistics and the Waiting-time Distribution of Solar Flare

Hard X-ray Bursts

N. Vilmer et al.

Production of Energetic Electrons in the November 27, 1997 Flare:

A Preliminary X-ray and Radio Analysis of Impulsive Phase and Shock Wave

Acceleration

K. Yaji

Nonthermal Electrons Acceletated in Solar Flare Loops by Microwave/X-ray

Observations

M. Ohyama and K. Shibata

X-ray Plasma (Plasmoid) Ejection and Magnetic Reconnection

09:00 - 9:30 D. Melrose:

Flare Models and Radio Emission

09:30 - 10:00 K. Shibata:

Reconnection model

10:00 - 10:20 T. Yokoyama:

MHD Simulations of Flares

10:20 - 10:40 Y. Uchida et al.:

Quadruple Magnetic Source Model of Arcade Flares and Arcade Formations

10:40 - 11:00 S. Hirose et al.:

Magnetohydrodynamic Model of Dark Filament Eruption and Arcade Flaring

11:00 - 11:20 (Break)

11:20 - 11:40 Poster Presentation and Discussion

T. Miyagoshi et al.

Current-injection Model for Loop Flares and Active Region Transient Loop

Brightenings

S. Morita et al.

Derivation of the 3D Structure of Flares in the Homologous Flare Series of

1992 February

K. Shibasaki

Observational Evidences of Ballooning Instability in Solar Flares

11:40 - 12:20 G.J. Hurford and the HESSI Team:

12:20 - 13:00 Poster Presentation and Discussion

V. Zandanov, A. Altyntsev and S. Lesovoi

Development of the Siberian Solar Radio Telescope

D.E. Gary and G.J. Hurford

OVRO Solar Array Upgrades in Preparation for MAX 2000

Q. Fu, Y. Liu, H. Ji and G. Huang

A Broadband Radiospectrometer and Preliminary Results

P. Kaufman et al.

Progress Report of the New Solar Sub-Millimeter Telescope Installation

G.J. Hurford et al.

SRBL - Solar Radio Burst Locator

Y. Suematsu

Development of New Solar Optical Observation Systems at Mitaka, NAOJ

N. Gopalswamy, D.L. Jones, M.L. Kaiser and the ALFA Team

Astronomical Low Frequency Array (ALFA): Imaging from Space

13:00 - 14:00 (Lunch Break)

14:00 - 14:40 T. Kosugi:

Scientific Objectives vs Coordinated Observation

14:40 - 15:20 Discussion for Collaboration

15:20 - 16:00 T. Shimizu:

SOLAR-B: The Next Japanese Solar Mission

16:00 - 16:20 CLOSING ADDRESSES