Long term data for Heliospheric science Nat Gopalswamy NASA Goddard Space Flight Center Greenbelt, MD 20771, USA

Transcription

1 Long term data for Heliospheric science Nat Gopalswamy NASA Goddard Space Flight Center Greenbelt, MD 20771, USA IAU340 1-day School, Saturday 24th February 2018 Jaipur India

2 CMEs & their Consequences

3 Outline CME Properties Heliospheric Phenomena Associated with CMEs Key Data sets CME Catalogs

4 A Total Solar Eclipse Revealing the Corona March 18, 1988 Philippines High Altitude Observatory Moon blocks the bright photosphere so we can see the corona, which is a million times dimmer. These structures are blown off occasionally as coronal mass ejections (CMEs). CMEs contain million-degree plasma with embedded magnetic field

5 Prominence Eruption as Proxy to CMEs Prominence Flare Shock Flux rope

6 Prominence Eruption Locations as a Function of Time html/prominence/ Super synoptic chart of microwave brightness temperature (Tb) from Nobeyama radioheliograph High-latitude Tb proxy to polar magnetic field strength (poloidal) similar to polar faculae (Sheeley 1964) Low-latitude Tb proxy to sunspot field strength (toroidal) Gopalswamy 2015 Prominence eruptions occurring at mid latitudes outside the active region belt: non-spot CME sources updated

7 The SOHO mission creates artificial eclipse using an instrument known as coronagraph, so the corona can be continuously observed Speed: km/s Mass: up to 100 billion tons Energy: up to Joules Frequency: per day CME Daily Rate CME Speed CME speed: 1400 km/s or 3 million mph

8 CMEs and Elephants: 1 CME = 10 9 elephants ESA/NASA Wikimedia Mass ~1.4x10 15 g Mass ~ 1.5 x 10 6 g

9 Mass Loss due to CMEs #CMEs per year ~10 3 Mass per CME ~4x10 14 g Mass loss due to CMEs (Ms = 2x10 30 kg) ~4x10 14 kg.yr -1 = 2x10-16 Ms. yr -1 Total mass loss due to CMEs = 2x10-16 Ms. yr -1 x4.5x10 9 yr = 9x10-7 Ms (about one millionth) Assumes constant CME rate Solar wind mass loss: ~2x10-14 Ms. yr -1 During solar maximum, CME mass loss up to 10% of solar wind flux Solar wind mass loss: ~2x10-14 Ms. yr -1 = 9x10-5 Ms

10 3D Structure of CMEs STEREO A Halo CME STEREO B Limb CME S Limb CME 3-D Structure of CMEs: look like a balloon as is clear from three views STEREO-B E STEREO-A

11 Range of Phenomena: 2005 May 13 CME SW Shock Source Location N11E km/s ESP 100 à3000 pfu SEP Halo CME Sun 33 h Earth Type II Burst shock in-situ view of the CME SSC UN/ESA/NASA/JAXA Workshop

12 Shock Solar Energetic Particles (SEPs) propagate along magnetic field lines in helical paths CME A fast CME driving a shock (cdaw.gsfc.nasa.gov) energetic protons are accelerated in the shock front just ahead of the expanding loop structures observed as mass ejections Kahler, Hildner, & Van Hollebeke (1978)

13 MARIE: The Martian Radiation Environment Experiment The MARIE instrument on the Mars Odyssey gave us a first look at the radiation levels faced by a possible future astronaut crew. The experiment took data on the way to Mars and in orbit, so that future mission designers will know better how to outfit human explorers for their journey to Mars. Another SEP event in October 2003 rendered MARIE inoperative. It is ironic, as MARIE was designed to measure the radiation environment at Mars. Mars Odyssey

14 Generally More SEP Events During Solar Max

15 GOES provides Proton flux for >1 MeV to >100 MeV Thermosphere 1 MeV proton 10 MeV proton Mesopause Altitude (km) Middle Atmosphere Mesosphere 100 MeV proton Stratopause 20 Stratosphere Tropopause Troposphere 1 GeV proton 0 Particle radiation from the Sun can destroy ozone: SEPs interaction with air molecules produce Ho x and No x radicals that react with O 3

16 A Type II Burst and the Associated CME The type II burst can track the CME-driven shock beyond the LASCO FOV and often to Sun-Earth L1

17 Range of Phenomena: 2005 May 13 CME SW Shock Source Location N11E km/s ESP 100 à3000 pfu SEP Halo CME Sun 33 h Earth Type II Burst shock in-situ view of the CME SSC UN/ESA/NASA/JAXA Workshop

18 Satellites Exposed to Interplanetary Space during Geomagnetic Storms GEO The CME shock pushes the magnetopause inside the geosynch. orbit

19 CMEs Near Earth SOHO CME Enhanced B rotation Bz always north Expansion Low T Clear magnetic field signature Temperature signature is also clear Alpha to proton ratio not clear Solar wind speed clear Shock Sheath - Ejecta Flux rope in white light: Chen et al. 1997

20 magnetic reconnection: A key physical process Reconnection leads to particle acceleration at the Sun à Flares Reconnection between interplanetary and Earth s dayside magnetic fields is the basic process for magnetic storms. A second reconnection on the nightside pushes plasma towards Earth Credit: ESA Dungey, 1962

21 Sheath1 MC1 Sheath 2 MC2 Gopalswamy et al., 2008 Sheath Superstorm N E S ENW (FN) Gosling and McComas1987; Tsurutani et al 1988 When MCs have high inclination the rotation is in the Y direction. In the Z-direction, the field will be always to the north or south. In this example, Bz is always north pointing so no storm. But there was a big storm due to the sheath consisting of intense south pointing Bz

22 CMEs contain Helical Magnetic Structure These are called magnetic clouds (MCs): Shock Sheath Cloud NS SN FS FN NS SN FS FN Southward component of MC magnetic field (negative Bz) causes the storm

23 Dst Index and SSN

24 Solar Source location important for Earth Impact 486/488 X17 X10 X8 X28 X5 X8 X1 X1 X17 X10 X28 Heliographic coordinates of the CME source location. CMEs occurring near the disk center head directly toward Earth causing storms (e.g. CMEs associated with the X17 and X10 flares) Dst index measures an average horizontal field of the Sun Storm conditions when Dst< -30 nt Major storms when Dst < -100 nt

25 Strong shock Magnetic connectivity (Outer structure) 1557 km/s 69% Halos = wide 988 km/s 68% Halos = wide Dst = -0.01VBz 32 nt Fast, large Bz, Earth-directed CMEs (Inner Structure)

26 Halo CMEs These are normal CMEs directed toward or away from the observer For a given coronagraph, halo CMEs represent a faster and wider population on the average (Quadrature between SOHO and STEREO: V=1155 km/s; W = 83 deg) Sensitive indicators of the state of the heliosphere G et al. 2010

27 the CDAW Data Center, others