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 CXE s 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 Io s (not the Sun s!) 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 Europa s 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]). Saturn s Rings Shine in Oxygen Ka Fluorescence Saturn s X-ray Lightcurve Follows the Sun s 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. 2006
Chandra 10th Symposium High resolution X-ray spectroscopy of Mars with XMM/RGS
7+ 6+ 6+ 4+ 7+ O O N C ? Ne C5+
CO2 + 50“ “halo”
+ 15“
- 15“
- 50“
Dennerl et al. 2006
Chandra 10th Symposium X-ray images of Mars in individual emission lines (!)
Emission centered Emission in crescent Emission above and below on disk (scattering). offset towards the Poles (!?) or in limb-effect Sun. crescent.
Alas, no obvious variation of x-ray signal in/out of hemisphere covering dust storm. SWCX Processes in the Earth s GeoCorona. Detection of heavy neutral atoms in the Earth s Magnetosphere implies interaction of the extended cold H envelope of the Earth with the solar wind via SWCX
¤ N.B. - SWCX more important than Jeans escape for terrestrial H loss budget. Evidence : - Atmosphere Explorer C 1974 - Arecibo Incoherent Scatter Radar of e- and neutral H abundances (Maher and Tinsley 1977) - IMAGE/LENA observations of magnetosheath quiescent solar behavior (Collier et al. 2001) - IMAGE/HENA - CME response (Brandt 2001) Chandra : Soft e- X-rays at the Earth : Auroral X-rays Auroral Precipitation + Atmospheric Scattering of Solar X-ray Radiation
Polar PIXIE : 3-10 keV SW Particle Auroral X-rays
¤
¤¤
Polar PIXIE : 3-10 keV In-Flare Scattering + Ar fluorescence Simulated X-ray images using detailed atmospheric and exospheric models of Venus for ..
.. scattering of solar X-rays .. solar wind charge exchange (logarithmic intensity scale) (logarithmic intensity scale)
~ solar maximum Dennerl et al. 2002, A&A 386 Gunell et al. 2007, GRL 34
Comets, Mars and Venus AOGS 2008 Simulated X-ray images using detailed atmospheric and exospheric models of Venus for ..
.. scattering of solar X-rays .. solar wind charge exchange (logarithmic intensity scale) (logarithmic intensity scale)
~ solar minimum Dennerl et al. 2002, A&A 386 Gunell et al. 2007, GRL 34
Comets, Mars and Venus AOGS 2008 ACE: Space Weather at 9P/Tempel 1
Solar wind data from ACE •Proton v, n •Composition
Map SW from ACE to comet SOHO EIT + LASCO Checks for Solar Oubursts X-ray Luminosity Trending of 9P/Tempel 1
Chandra swift chandra (triangles) SWCX SWIFT model (squares)
Proton Flux
QGas.
SOHO/LASCO Swift data from Willingale et al ( 06); Comet gas production from Schleicher ( 06) Natural Outburst and Lisse ( 06) Solar CME
•Results : No prompt X-ray flash detected Deep Impact! •Increased X-ray flux ≤ 20% over 2 days à consistent with coma observations (Kuppers 05, Keller 05, Farnham 07) •Good agreement between observed flux & SWCX model Chandra Spectra of Comets: H Three competing emission features: H O VII ~ 1. C and N emission below 500 eV E 2. O VII emission at 565 eV E C+N 3. O VIII emission at 654 eV
low abundance of highly charged oxygen à cold wind Bodewits et al. 2007 F high abundance of highly charged oxygen à hot wind F
à flux ratios of all observed comets: G flux increases G cold, fast, polar O VII
C / C warm, slow, equatorial A O VIII O VII O
/ A
C+N B B hot, fast, O VII
“disturbed” ≪ D D O VIII / O VII C+N
Bodewits et al. 2007 Studies of Planets and Comets in the X-ray
C.M. Lisse (JHU Applied Physics Laboratory); A. Bhardwaj (SPL, Vikram Sarabhai Space Centre); K. Dennerl (MPI für extraterrestrische Physik); S. J. Wolk (Chandra X-ray Center)D. J. Christian (Queens University Belfast);; D. Bodewits (NASA/GSFC); T.H. Zurbuchen (University of Michigan)
Chandra s First Decade of Discovery Boston, MA, 25 Sept 2009 Questions from Talk:
Careful with Lx ~ nsw * nneutral; only for collisionally thin systems, and for low- dust systems (Auger electron)
Lgalaxy ~ 10^36 erg/sec assumes all stars like the Sun NOW. Need to take stellar luminosity function in x-rays and sum over the galaxy.
Can detect SW-dust charge exchange from heating of dust? (Randall Smith)
Does SW shock at a comet bowshock? How much heating of the ions does it cause? Can see heating in narrow lines, like O+7 at ~600 eV?
Is Snowden et al. XMM SWCX flarng result from Geocoronal or Heliospheric emission? Not clear – but do need a huge density of SW texplain it via heliosphere alone. (N.B. : Expect hard bowshock for the Earth, factor of 4-5 density enhancement in SW and cold H-atoms streaming from the Earth)
If Helisopheric emission dominates & is strong, then should expect to see astropsheric emission from the Alpha Centauri system, but don‘t. Wargelin et al. worked this out & published it?
SWCX: (f+i)/r = 5.8, Thermal : (f+i)/r ~ 1 Spectral Modeling & Lab Measurements of Cometary CXE
LS4: EUVE/Chandra
Solar Wind
Coma
• OVII/OVII line ratios variable • He+,background signal huge at E < 250 eV • All lines, or lines + continuum? • Fast vs slow solar wind - expect different spectra • Auger e- quenching on dust, surfaces (Hale-Bopp)? • Role of Collisions in the cometary atmosphere? SOHO/CELIAS X-ray Emission from the North Pole
Observations: Theoretical CX spectra Bhardwaj et al. (2005) Oxygen and Sulfur Ions Chandra (Kharchenko et al. JGR 2008)
S/O ratio = 0.28
Photon Energy [ keV ] ~40-min Periodicity Seen in X-rays and THz Radio, But Not by Galileo and Cassini s/c in Any Other Passband!