Solar System X-ray Targets for AXIS C.M. Lisse (JHU APL) & B. Snios (Harvard-SAO) Comets Charge Exchange Venus Mars Scattering Aurorae Rings Disk Disk Saturn Jupiter S. Wolk 2009 Some of the currently known sources of X-rays in the Solar System. The complete list incl‘s the Sun, Planets, Comets, Moons, the Io Flux Torus, and the Heliosphere itself. [See review in PSS 55,1135 (2007) and update in Encyclopedia of the Solar System, 2014 by Bhardwaj et al.] It all starts with Living With the Sun, an average G2V Main sequence star of 4.56 Gyr whose corona actively emits Lx ~1027 erg/sec… …and streams of Solar Wind H+, He+2, plus Highly Stripped Minor Ions (CV, NVI, OVII, NeIX, etc., at ~10-3 of the H+ abundance) emitted at a total rate of MSW ~ 10-14 M¤/yr into the Heliosphere & InterPlanetary Space. Ulysses - Solar wind properties at: Solar Minimum Solar Maximum Polar Solar Wind: fast (~700 km/s), low density, cold, less ionized, regular Equatorial Solar Wind: •Slow (~400 km/s), warm, more ionized, high density, quiet •From coronal holes : fast, cold, less ionized, disturbed (like polar wind) • With CMEs or flares : fast, hot, McComas et al. 2003 highly ionized, disturbed. Chandra 10th Symposium Thus our Solar System is awash in MEASURABLE 106 K Solar Wind particles and High Energy photons from the Sun, driving NEARBY soft (0.1 – 1.0 keV) X-ray emission in response from the interplanetary and heliospheric environments. 4 Main Soft X-ray Processes Govern Solar System X-ray Generation : •Auroral Precipitation •Charge Exchange •Scattering •Fluorescence Importance & Relevance : •SW Diagnostics – flux density, composition, charge state •SW & X-ray Effects on Planetary Bodies (atmospheric ionization & destruction, high energy chemical alteration [Comets, MAVEN at Mars]) •Heliosphere Structure & Dynamics (Sun in the ISM) •Giant Planet Magnetohydrodynamics Example #1 of Solar System Processes Producing X-rays: Charge Exchange Interaction between the Gravitationally Unbound Neutral Atmospheres of Comets and the Solar Wind 107-8 km Ion Tail Sola r 106 km (Cravens 2000) Win Bowshock d 107-8 km Dust Tail 10 km Nucleus 103 km Contact Surface D/Linear S4 2000 Solar Wind Charge Exchange (SWCXE) is the Dominant Chandra ACIS-S Ionization Process for Outflowing Cometary Gases 0.3 – 0.8 keV Comets Display 73P/SW-3 2006 8P/Tuttle 2008 Diverse X-ray Qgas (mol/sec) Morpholgies, Extents, and 103P/Hartley 2 Luminosities Christian et al. 2010 Wolk et al. 2009 2010 2P/Encke 2003 Lisse et al.2013 C/ISON 2013 9P/Tempel 1 2005 Predicted Morpholgical Neutral Gas Production Dependence Lisse et al. 2005 Snios et al. 2016 + Deep Impact! C/Hyakutake 1996 B2 Lisse et al. 2007 D/Linear S4 2000 ~22 Yrs of Solar Wind – Comet Neutral CXE Comet Morphologies : Sunward Facing, Coma Localized, Lisse et al. 2001 Collisionally Thin or Thick Lisse et al. 1996 SWCX Depends on the Solar Wind (r,T,v) & Coma Density & Composition Coma Neutral Density Ions Are Not Fully Depleted At Nucleus SW Ion Flux Aq+ + B A(q-1)+(nl) + B+ + hn • SWCX cross sections are target and velocity dependent • Quasi resonant • Excited state • X-ray: C5,6+, O7,8+, N6,7+ • FUV: He2+, He+ X-rays! ENAs! ROSAT X-rays?? LTEs Cravens et al. 2002 Heliosphere: In-Streaming neutral ISM H, He gas CXEs with the SW & emit X-rays SOHO/SWAN Ly-Alpha Koutroumpa et al. 2008 SWCXE spectral XMM MOS, signature in Snowden et al. 2004 heliospheric background observations. DXS Background ACIS-S Lunar night- side emission, Wargelin et al. 2004 (see also Wargelin et al. 2009 Chandra posters @ this meeting) Lunar X-rays : Scattering on Day Side + SWCX in Fore-Column on the Nightside Dayside : O, Si, Mg, Al fluorescence lines from lunar soil + rock. Non-zero Non-zero ¤ Emission! Emission! Nightside : ~1% Dayside Rate, Oxygen SWCXE lines. Dennerl et al. 2002 Chandra 10th Symposium First evidence for Exospheric X-ray Emission from Another Planet: Disk = Scattering + Halo = Exopsheric Charge Exchange Chandra Observation Dennerl 2002 Chandra 10th Symposium SWCX at Mars Singlet State Triplet State O6+ 1s 2p 1 1 P SWCX: f+i/r = 5.8 (6 by thery; ~1 for thermal) 1s 2p 3 P0,1,2 1s 2s 2 1 1S 0 0 21.60 Ǻ 1s 2s 3S 1 574.0 eV 21.81 Ǻ 568.5 eV (2 photon continuum) 22.11 Ǻ 560.9 eV 2 1 1s S 0 Dennerl et al. 2006 Comets, Mars and Venus AOGS 2008 January 2001: first X-ray image of Venus (Chandra ACIS-I) First X-ray observation of Venus during solar maximum: Scattering of solar X-rays detected, but no conclusive evidence of SWCX. Solar X-rays Venus ACIS-I Dennerl et al. 2002, A&A 386, 319 Yohkoh SXT 0.25 – 4.0 keV 1995 Venus emission Is dominated by a large 1991 x-ray scattering component due to Chandra ACIS-I Its proximity to the 0.4 – 0.9 keV Sun. GOES-7, 8, 10, 12 1.6 – 12.4 keV Dennerl et al. 2008 Chandra 10th Symposium Second Chandra observation of Venus, 2006 March 27 (ACIS-S, 74.9 ks) First evidence for exospheric X-ray emission from Venus SWCX During Solar Max ! O6+ charge exchange N6+ charge exchange limb disk Dennerl et al. 2008 charge exchange fluorescence charge exchange 400* eV 615* eV 660* eV 900* eV * energies shifted by ~110 eV due to optical loading Chandra 10th Symposium Jovian X-rays : Disk Scattering of Solar X-rays + Auroral Precipitation + Polar SWCX Jovian Disk X-rays Correlate With Solar X-ray Output… ¤ …and the Polar X-ray Spectrum can be fit by a Combination of Ios (not the Suns!) O and S undergoing CXE (no solar wind C, Hui et al. 2009)…at an Unexpected Polar Location. Hui et al. 2009 Io, Europa, Ganymede, and the Io Plasma Torus have been detected in the X-ray. Does the IPT provide the S, O atoms for Jupiter s Polar X-ray emission? Have we detected the root of Europas Neutral Atom Torus (Mauk et al. 2003)? Chandra ACIS …and now X-ray (Bhardwaj et al. 2005), showing high variability and polar enhancement, and now recent new Cassini evidence of polar e- precipitation & UV auroral emission]). Saturns Rings Shine in Oxygen Ka Fluorescence Saturns X-ray Lightcurve Follows the Suns Closely (Much More Than Jupiter) Cassini‘s UVIS Observation of the Saturnian Aurora (Pryor et al. 2011) Generalization: Do Exo-Jupiters Make X-rays? Giant Planet w/ strong magnetic field, rapid rotation, and moon source of neutral gas species? => Saturn + Enceladus should show intrinsic x-ray production, like Jupiter + Io (& Europa?) Or will a close-in hot Jupiter with a strong magnetic field + incommensurate orbital and stellar rotation periods do? Ex. : HD 189733 (Pilliteri et al. 2011) Near-Future Solar System X-rays Low Hanging Fruit With AXIS • Detection of X-ray Emission from Uranus & Neptune, examples of the most common type of exoplanets • Heliosphere & Heliopause Spectral Profiles & Maps (+Nearby Astrospheres?) • Saturnian Aurora • Tracking Flares & CMEs through the Solar System • Deep Comet Survey => Mapping the Solar System With Comet CXE : High Latitude & Main Belt Comets, Active Centaurs. Ceres = Comet Pizzaro? Pluto X-ray vs. optical flux levels for solar system objects detected in the X-ray. Pluto’s relatively high X-ray/optical flux ratio is similar to that of comets and the Io plasma torus in the Jupiter system. (After Dennerl+ 2012) Jovian UV and X-ray Emission are Coupled? Footprints are off. X-rays 1st High Resolution Comet X-ray Spectrum: XMM/RGS of C/2000 WM1 Dennerl et al. 2010 The Study of Solar System X-rays is a Very Rich Field, Still Developing. Low Lx but important plasma &scattering processes. Next Up : Mercury, Uranus? High Latitude & Main Belt Comets? Trojan Asteroids? Active Centaurs? YSO dust evolution? Other Astrospheres & the Soft (1/4 keV) X-ray Background? Bhardwaj, Lisse, et al. 2007 & Encyclopedia of the Solar System II, 2008 Current Work & Speculations • Main Belt Comets not Detected by XMM (Dennerl et al. 2011) • Heliopause complicated, ribbon-like structure?? • Total energy in Heliosphere, other astrospheres, galaxy from CXU ~ 1025 erg/sec/Sun*1011 Suns = 1036 erg/sec (compare to Starburst rate) • Assumes all stars have solar value – but can different types of stars dominate? Lx ~ nSW * nNeutral (assuming collisionally thin SWCX) where have both high? Protostars, AGB stars? • HD 189733 lightcurve, WASP-12-b may be very good exo- system SWCX candidates – both contain Jovian planets experiencing very high SW particle fluxes • Giant planets all have SWCX (JUNO @ Jupiter) – but maybe not Ice Giants because of much different magnetic field structure? Pluto ACIS-S Observation in Support of NASA New Horizons Flyby Mission 24 February 2014 • 35 ksec stare performed to detect CXE from SW vs 1027 – 1028 mol/sec of N2 escaping Pluto’s atmosphere • SW monitored by New Horizons/PEPPSI 4 AU upstream of Pluto • No obvious ACIS-S detection found. Maximal potential signal due to Pluto estimated as ≤ 3 photons above background. • 3 photons over background => 1.8 x 1028 mol/sec N2 loss rate, a useful upper limit for Pluto global atmospheeic models pre- encounter ACIS-S Pt Source Pluto Track Photometry in the Pluto Field BD-20 5320? B-V = 1.19 (K5V?) TYC 6289-2743-1 ? B-V = 1.71 (M7V?) Box Photometry Very Bright PN or Galaxy? X-ray grating spectrum of Venus (Chandra LETG/ACIS-S) C-Kα N-Kα ? O-Kα O-Kα CO,CO2: 1s → π* ? Dennerl et al. 2002 Chandra 10th Symposium High resolution X-ray spectroscopy of Mars with RGS “disk” + 10“ - 10“ dispersion direction Dennerl et al.