Solarsystem observations with HerschelALMA

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Solar-system observations with Herschel/ALMA

• T. Encrenaz, D. Bockelée-Morvan,
• J. Crovisier, E. Lellouch
• LESIA, Observatoire de Paris

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Outline

• Why the far-IR/submm/mm range?
• Major objectives of solar-system research
• Venus, Mars and the giant planets
• Satellites, distant asteroids and TNOs
• Comets

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Why the far-IR/submm/mm range?

• Solar-system objects are COLD objects which
  radiate at low frequencies
• Strong molecular rotational transitions
• Ideal for
• planetary atmospheres
• cometary atmospheres
• distant objects (TNOs)

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Many major discoveries in planetary and cometary
science

• First detection of HCN in Comet Halley (1986)
• Over 20 parent molecules detected in Hale-Bopp
  (1997)
• First detection of a stable atmosphere (SO2)
  around Io (1990) also SO and NaCl(2002)
• Detection of new molecules in Jupiter after the
  SL9 collision (1994)CO, CS, OCS, HCN
• First detection of H2O2 on Mars (2004)

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Major issues in solar-system sciences

• Origin of the solar system
• Giant planets  composition D/H, He/H, oxygen
  source
• Comets  composition and link with ISM minor
  constituents, D/H in various species
• TNOs Ts/albedo
• Evolution of solar-system objects
• Minor constituents and dynamics of planetary and
  satellite atmospheres
• Comets  activity, physico-chemistry and
  thermodynamics

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Venus

• CO, H2O/HDO observed in the mm range -gt vertical
  distributions wind measurements
• No observation with ISO nor Herschel
• Perspective with ALMA
• velocity field from CO, H2O, H218O maps (-gt D/H)
• dynamics of the mesosphere (z 100 km)
• zonal super-rotation, global circulation
• Search for minor mesospheric species (HCl, H2S,
  SO2)
• Follow-up of Venus Express

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Mars a prime objective of planetary exploration

• Questions
• Past and present climate
• Water cycle
• Evidence for liquid water in the past?
• Evidence for traces of fossil life?
• An extensive space exploration with orbiters and
  landers ( Follow the water )

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MarsHigh-resolution spectroscopy

• CO, H2O/HDO/H218O observed in the mm range -gt
  vertical distributions
• ISO, Odin, SWAS -gt water distribution
• Perspectives with Herschel and ALMA
• H2O, CO and isotopes (in part. D/H)
• Minor species H2O2, O2, O3
• Search for undetected species HCl, NH3, HO2,
  H2CO, SO2, H2S, OCS

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MARS OBSERVATIONS WITH ODIN
Biver et al., 2004
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Ozone on Mars with Herschel
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NH3 on Mars with Herschel and ALMA (Q 5 10-10)
Herschel
ALMA
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Mars A 3-D dynamical picture of the middle
atmosphere(winds, T(P) and water mapping)

• First maps using CO(2-1) at IRAM (30m PdB)
• Comparison with GCM good overall agreement but
  strong retrograde winds observed whatever the
  season
• -gt future observations important for better
  understanding the martian climate
• -gt Major objective for ALMA
• Complementarity with space missions
  (Mars Express and future orbiters )

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Mars velocity field, IRAM PdB (Moreno, 2001)
z 50 -70 km
Perspectives with ALMA DV 3-5 m/s, spatial
resolution on Mars about 100 km
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Giant planets formation

• D/H a tracer of giant planets  formation
• In Jupiter and Saturn (mostly made of protosolar
  gas) reflects the protosolar value
• In Uranus and Neptune ( mostly made of an icy
  core) enriched vs protosolar value
• Expected
• (D/H)PS(D/H)J lt(D/H)Slt(D/H)U,Nlt(D/H)C
• Confirmed by ISO Galileo measurements

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HD ISO/SWS Feuchtgruber et al., 1999 Lellouch et
al., 2001
Deuterium in the Solar System
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What to do with Herschel?

• New measurement of HD at 56 and 112 mm on the
  four giant planets with PACS
• Questions
• Is (D/H)S gt (D/H)J ?
• Are (D/H) in protoneptunian ices different from
  cometary values?
• Is D/H in Oort-cloud comets the same as in
  Kuiper-Belt comets?

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Giant planets evolution

• He/H a tracer of giant planets  evolution
• In Jupiter and (even more) in Saturn He is
  expected to be depleted vs the protosolar value
  due to condensation in liquid hydrogen during the
  cooling phase
• In Uranus and Neptune
• no liquid hydrogen expected
• but H partly linked in ices
• -gt He/H might be enriched in the gas phase
• Present determination are still uncertain (except
  Jupiter)
• Future Cassini CIRS (Saturn), Herschel/PACS
  (Uranus,Neptune), from the far-IR continuum

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He/H in the giant planets
Jupiter Galileo mass spectrometer Saturn,
Uranus, Neptune Voyager (IRIS)
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The oxygen source in the giant planets and Titan

• H2O and CO2 emissions detected by ISO-SWS
  SWAS/ODIN (Jupiter, Saturn)
• Comparable H2O input fluxes 105-107 cm-2 s-1
• Possible sources
• interplanetary flux (U, N),
• local source (rings, satellites)(S, T?),
• cometary impacts (J?)
• Important implications on
• Dust production and water content at large Rh
  (collisions in the Kuiper Belt?)
• Rate of cometary impacts

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Observation of the H2O vertical distribution in
Jupiter with SWAS
Bergin et al. 2000
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Oxygen source What to do with Herschel and
ALMA?NB For Saturn complementarity
Herschel/Cassini-CIRS

• Herschel
• H2O abundance and variability
• Possible role of cometary impacts
• H2O vertical distribution (HIFI)
• Constrains on transport models
• Low-resolution mapping of J and S (PACS)
• Possible trapping in aurorae
• ALMA HDO high-resolution mapping
• Determination of D/H in external source?

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Why are Uranus and Neptune so different?

• Strong internal source in Neptune, not in Uranus
• CO and HCN abundant in Neptune s stratosphere
  (CON 10-6, COU 3 10-8)
• CO mostly internal in Neptune, probably external
  in Uranus
• Uranus is much more sluggish (eddy diffusion
  coefficient 103 times less than in Neptune)

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What to do with Herschel and ALMA?

• Search for tropospheric CO and PH3 (tracer of
  vertical motions in Jupiter and Saturn s
  tropospheres)
• PH3 expected to be abundant in Neptune,
  apparently absent in Uranus (convection
  inhibited?)
• Search for CH4 emission lines
• oversaturation observed in Neptune, not in Uranus
  
• Search for photochemical products in Neptune
  (nitriles)

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Detectability of stratospheric CH4 in Uranus and
Neptune with Herschel/PACS
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Satellites Pluto with ALMA

• Io
• Search for minor species (H2S, S2O, KCl, SiO)
• SO2 low-res. Mapping (-gt volcanism monitoring)
• Titan (complementarity with Cassini/CIRS)
• Mapping of CH3CN, HC3N at z 500 km
  -gt dynamics,
  photochemistry
• HCN winds (low-res.map), D/H
• Triton and Pluto
• Search for CO, HCN

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Distant asteroids and TNOs

• Interest of far-IR/submm measurements
  determination of diameter Ts (in the visible
  aD2 is measured)
• Spitzer program (GTO) 114 TNOs, 14 Centaurs
• With Herschel possible to reach D300 km at 40
  AU
• With ALMA 300 km at 80 UA

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Detectability of TNOs with Herschel/SPIRE
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Observations of comets with Herschel and ALMA (1)

• Water-rich objects -gtStudy with Herschel
• Activity monitoring
• D/H -gt origin
• Tinitial from ortho/para ratio -gt origin
• Tcoma from H2O line intensities -gt thermodynamics
• Doppler shifts -gt velocity fields -gt
  thermodynamics, study of jets...

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Observations of comets with Herschel and ALMA (2)

• Many complex parent molecules -gt study with ALMA
• Search for new species (possible candidates all
  ISM molecules!)
• Chemical diversity among comets
• Relative abundances -gt link with ISM
• Isotopic ratios (D/H in HCN, HNC, H2CO) -gt
  link with ISM
• Velocity fields -gt thermodynamics, origin of
  outgassing (nucleus, grains), structure (jets)

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The heritage from ISO high-resolution
spectroscopy of rovibrational bands
Crovisier et al., 1997
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The heritage from SWAS the 557 GHz line in
comet C 1999 H I (Lee)
About 12 comets observed with SWAS and/or ODIN
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The heritage from ground-based
observations Evolution of production rates with
heliocentric distances
Biver et al., 2002
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Parent molecules observed in comets

• In the far-IR/radio range
• H2O, CO, CH3OH, H2CO, HCN, H2S
• NH3, HNCO,CH3CN,HNC, OCS (Hyakutake)
• HCOOH, CH3CHO, HCOOCH3, NH2CHO, HC3N, H2CS, SO,
  SO2 (Hale-Bopp)
• In the near-IR range
• H2O, CO, CO2, H2CO, OCS, saturated unsaturated
  hydrocarbons
• CH4, C2H2, C2H6, OCS, NH3 (Hyakutake, Hale-Bopp)

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Water in comets (Herschel)

• H2O in a sample of weak comets (down to Q1026
  s-1)-gt prod. rates (HIFI, 557 GHz)
• H2O monitoring as a function of Rh (HIFI, 557
  GHz)
• Search for H2O in distant weakly active objects
  (link with asteroids)
• Measurement of D/H in H2O

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D/H in comets

• D/H in water a stringent clue to the formation
  of comets (T, Rh)
• D/H is known for only 3 Oort-cloud comets, not
  for Kuiper-belt comets
• HDO lines will be searched for with HIFI for
  bright comets (Q gt 2 1028 s-1)
• D/H in other species (HCN, HNC) will be searched
  for with ALMA

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A few good targets for Herschel

• 8P/Tuttle January 2008, QH2O 3. 1028 s-1
  D 0.25 AU
• 46P/Wirtanen February 2008, QH2O 1. 1028 s-1
• 85P/Boethin December 2008, QH2O 3. 1028 s-1
• 67P/Churyu.-G December 2008, QH2O 5. 1027 s-1
• 22P/Kopff May 2009, QH2O 2.5 1028 s-1
• 81P/Wild 2 February 2010, QH2O 1.3 1028 s-1
• 103P/Hartley 2 October 2010, QH2O 1.2 1028
  s-1 D 0.12 AU

possible brighter targets as Targets of
Opportunity
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Mapping cometary atmospheres
CO 230 GHz/Hale-Bopp with IRAM PdB
ALMA Instantaneous 3-D maps of gaseous and dust
(thermal) emissions Coma morphology, spiral
gaseous jets, nucleus outgassing, rotation
properties, dust/gas links Gas temperature and
velocity maps Nucleus thermal emission on long
baselines size, albedo
Henry,2003
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In summary...

• Herschel/ALMA observations of solar-system
  objects will be precious in addition to space
  missions (MEx, VEx, Rosetta)
• D/H in the solar system-gt origins
• Search for minor species in comets-gt link with
  the ISM
• Observation of many samples (KB comets, TNOs)
• High-resolution mapping of planets and satellites
  
• A major program with Herschel H2O in the solar
  system
• Formation of planets and comets
• Activity of outer small bodies and water content
  in outer planetesimals