Where did it come from? If time permits What is it doing? Where is it heading? How do we know what we know? What can an amateur see? The Grea t America n Eclipse 201 7! International Astronomyyy Day 2 spectral type = G2 (yellow/green) apparent Mv = -26.7 (4.83 abolute) mass = 2x1030 kgg( (300k * Earth ) radius = 696,000 km (109 * Earth) composition = 74.9% H, 23.8% He, 1.3% “metals” Sun contains ~99.8% of all solar system mass Compared to other stars in our galaxy, our Sun is average Sun is middle-aged, roughly halfway through a ~10Byr lifespan ilovetheuniverse.com us 3 CORE: fusion engine (25% Rsun) RADIATIVE (25-75% Rsun)/ CONVECTIVE (75-100% Rsun) ZONES: transfer energy to surface PHOTOSPHERE: photons are free, what we see (peak emission)* CHROMOSPHERE: see with Hαlpha CORONA: see during eclipse (or FUV + EUV), hotter than ppphotosphere! abyss.uoregon.edu * Takes between 1kyr & 1Myr for a photon produced in the core to make it to the photosphere 4 ProtonProton-- Proton Chain CNO Cycle (most important) Core energy production ~280 W/m3 (lower than human metabolism) ~4 Mtonnes of mass converted to energy per sec – this plus solar wind means Earth- Sun distance increases 1.6cm/yr 5 wikipedia.org our star has finite “accessible” supply of fusion-able hydrogen when supply of H runs out (5-6 Byr), move to next step in evolution – its giant stage core heats enough for C fusion of H in shell around core fusion, He & H fusion starts, radiation rapidly expands continues in shells medium mass & cools outer layers (0. 5 < M < 1. 5) H-fusion in core stops, core heats enougg,h for He fusion, core collapses H fusion continues in shell how far evolved depends on mass 6 luminous blue variables blue super giants yellow hyper giants red super giants red giants Wolf-Rayet stars asymptotic giant branch Sol will become a red giant Our Sun ending on the asympto tic branch Increase in diameter to ~1 AU Giant phase will last ~ 1 Byr wikipedia.org 7 medium mass C or O-type white dwarf (0. 5 < M < 1. 5) + planetary nebula throughout red giant stage once fusion stopped (more so at the end), strong only core remains, solar winds blow outer layers surrounded by nebula of star into space of star’s former outer all imaggpes: J. Thompson layers M27 Dumbbell M57 Ring M76 Little Dumbbell M97 Owl ngc2392 Eskimo ngc7008 Fetus ngc2438ngc3242 Ghost ngc7048 ngc7293 Helix ngc6826 ngc7662 of Jupiter 8 ½ of Sun’s energy is infrared without ppproper protection you’re literally cooking your eyes! commons.wikimedia.org/ Robert A. Rohde 9 Photosphere Sun only room temp emits in infrared commons.wikimedia.org 10 core radiative ctive zone ne ee oo z conv Hα 6562.8 Å http://www.aanda.org, “Response of the solar atmosphere to magnetic field evolution in a coronal hole region “, S. H. Yang 11 Solar interior is Sudbury Neutrino Detector opaque – can’t use photons to observe Helioseismology: analyse vibra tion patterns visible on surface Neutrino Detectors: count neutrinos of various flavours to understand what is happening in core PPTX “The Sun” by Shana Nash (from Slideplayer.com) 12 NASA/SDO/Goddard Space Flight Center 13 https://www.youtube.com/watch?v=lpzCSZ7Eerc NASA/SDO/Goddard Space Flight Center 14 Energy generated in the sun’s center must be transported outward. In the photosphere, this happens through… Cool gas Convection: Bubbles of hot sinking down gas rising up about 1000 km Granules (bubbles) last for about 10 – 20 min. PPTX “The Sun” by Shana Nash (from Slideplayer.com) Plasma has electric charge – affects magnetic fields & visa-versa Sun rotates faster at equator (25 days @ equator, 27.8 days at 45º) differential rotation winds up magnetic field lines field lines loop, cross, break, combine…very complex a lot of energy tied up in Sun’s magnetic field (impor tan t la ter ) PPTX “The Sun” by Shana Nash (from Slideplayer.com) 16 As field lines wind-up, can tangle and exit surface of ppp(hotosphere (ie. sunspot) After 11 yygpears magnetic pattern becomes so complex the field structure re-arranges itself New magnetic field structure similar but reversed After field orientation reversed, cycle repeats PPTX “The Sun” by Shana Nash (from Slideplayer.com) 17 Cycle start – sunspots at Maunder Minimum higher lat’s As cycle ends – sunspots near equator Number of spp/ots tracks w/ complexity of magnetic field StSunspot obibserving used to Maunder Butterfly Diagram monitor solar activity Activity fluctuates over long time scales also (not just every 11yrs) PPTX “The Sun” by Shana Nash (from Slideplayer.com) 18 Core – Radiative – Convective = forget it! (un less you want to build neutr ino de tec tor in your basemen t) Photosphere = white light Lower Chromosphere = calcium II - K Mid-Upper Chromosp here = hyd rogen II - α Corona = total solar ecli(ipse (naked eye ) 19 view visual band at safe intensity several options available – use existing scope most economical way to observe Sun britastro.orggy/mercury2016 www.starizona.com, www.flickr.com/photos/alexandra4 www.365astronomy.com Alexandra Hart Solar Filter Herschel Safety Wedge glass or thin film blocks 99.999% of light Rear Projection attach over front of scope wedggpe prism directs 4.6% to ey e, rest out back project image onto white background larger scopes use part-aperture insert into focuser, then eyepiece into wedge many people view at same time improved image – sunspots & some granulation refractors only, 6” or smaller not the best image – see sunspots only reasonably affordable solution best image – lots of sunspot & granule detail use a junk eyepiece! (will get cooked) most expensive solution ($800 CAD) cheapest solution naked eye solar glasses ~$0-20 20 all images: J. Thompson Solar FilterUV/IR Cut Herschel Safety Wedge UV/IR Cut #29 Red Solar Continuum 21 dark granule image: J. Thompson filaments pores umbra granules penumbra light bridge streamer WLF = white faculae bi-polar light flares, sunspot very intense group magnetic activity around uni-polar sunspots, sunspot rare to see • SUNSPOT: concentration of magnetic field lines, • GRANULES: visualization of convection cells in • PORES: small dark spots, start granule size in areas disrupts convection so cooler, often in pairs N-S photosphere, light-hot-rising, dark-cool-sinking with faculae, larger ones may grown into sunspots • FACULAE: local bright spots between granules, • LIMB DARKENING: gradual solar disk darkening as • LIGHT BRIDGE/STREAMER: bright band cutting into due to decreased magnetic activity, see easier at you move towards limb, optical affect umbra & sometimes penumbra, usually thin limb, linked to sunspot formation 22 view narrow (0.5-80Å) bdband in NUV (393-398nm) use your existing scope + ERF (energy rejection filter) expensive way to “observe” Sun - camera only! luntsolarsystems.com agenaastro.com daystarfilters.com Screw-On Filter Fixed Etalon Adjustable Etalon etalon typically gives more accurate band pass most affordable of methods ($350) than screw-on filter use very accurate temperature controlled etalon provides good images but not “the “can” give sharper image than screw-on best” only Lunt Ca-K module available, Coronado PST provides excellent detail very flexible to use no longer for sale very expensive! ($1200 – 6000) relatively expensive ($800-2000) 23 Baader Herschel Wedge + Omega Optical Ca-K all images: J. Thompson 24 Jamey L. Jenkins, Observing the Sun: A Pocket Field Guide k3 plage k2 prominence(?) filaments umbra k1 light bridge penumbra Most Ca-K filter systems are K1-K2 sub-bdband • K-GRAINS: small bright points, k-grains away from other activity, pores within middle of super granule, chromospheric short lived (~10min) netktwork • PLAGE: FhFrench for “b“bh”each”, super patchy bright regions w/ higher temp., found most (or mega) often near sunspots, visible predominantly in Ca-K, mark granule area of increased magnetic activ ity, connection to flfaculae unclear dark • CHROMOSPHERIC NETWORK: granule bi-polar weak but bright background pattern, overlays super- sunspot granules in photosphere (large group granules scale convecti)ive pattern), last day or so • SUPER GRANULE: single cell within network, ~30,000km size limb darkening image: J. Thompson 25 very narrow (0.3-0.7Å) band in dark red (656.28nm) all options require tuneable etalon most expensive way to observe Sun -& most interesting! daystarfilters.com meade.com luntsolarsystems.com Tilt Tuned Etalon tuning of waveband achieved by Dedicated Hα Scope Temp. Tuned Etalon finely adjusting angle of etalon (thum bscrew or pressure) same tilt tituning & blkiblocking filter as use very accurately controlled when buy etalon separately etalon paired with blocking filter etalon (changes thickness with T) can stack etalons for better contrast can stack etalons for better contrast provides excellent detail can only use scope for solar viewing use with existing scope – refractor only very expensive! ($1200 – 16,000) $1200-10,000 26 $1000-8000 much cheaper DIY tilt-tuned possible but poor performance all images: J. Thompson 27 plage • SPICULES: individual jets of hot gas, moving • EMERGING FLUX REGION: area of increasing magnetic verticallyyp at up to 50, 000 kph, last ~10min activity (growing plages, start of sunspots) • FIBRILS: spicules that are stretched & distorted • ARCH FILAMENT SYSTEM: kind of fibril in active regions, by nearby magnetic activity (sunspot) joins areas of opposite magnetic poles • PROMINENCE: cloud of gas above surface • FILAMENT: a prominence viewed from above emerging • FLARE: sudden extreme release of energy flux region sto red in magne tic fieedld of an activ e regegoion ()(EFR) sunspot quiet region filaments (QRF) active region filaments (ARF) spicules (chain) arch filaaement system (AFS) spicules spicules flare (limb) (()bush) image: J. Thompson fibrils (colour inverted for clarity) prominence dark = hot 28 Features change visibly over course of 5-10min – esp.