1 / 14

Comets with ALMA N. Biver, LESIA, Paris Observatory

Comets with ALMA N. Biver, LESIA, Paris Observatory. I Comets composition Chemical investigation and taxonomy Monitoring of comet outgassing II Mapping of cometary atmospheres 3-D Gas and dust jets Physical properties of the coma and extended sources.

donkor
Download Presentation

Comets with ALMA N. Biver, LESIA, Paris Observatory

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Comets with ALMA N. Biver, LESIA, Paris Observatory I Comets composition Chemical investigation and taxonomy Monitoring of comet outgassing II Mapping of cometary atmospheres 3-D Gas and dust jets Physical properties of the coma and extended sources

  2. ALMA and the composition of comets: • Observing all types of comets (Kuiper Belt ones), new molecules Biver et al. 2002, E.M.P. 90, 323

  3. Measuring isotopic ratios in comets with ALMA D/H: HDO/H2O 2× terrestrial in 3 comets, DCN/HCN 7× higher in Hale-Bopp HDO with ALMA: in bright comets (Herschel more sensitive) D/H in other molecules with ALMA (DCN, CH2DOH, HDCO, NH2D,…) 13C/12C: terrestrial in > 6 comets ALMA: H13CN, 13CS, 13CO, 13CH3OH,… 34S/32S: ~ terrestrial in 2 comets ALMA: C34S, H234S 18O/16O: ~ terrestrial in 4 comets (H2O) 15N/14N: ~terrestrial in HCN Hale-Bopp but twice higher in CN in > 4 comets? ALMA: HC15N, H15NC? Hersant et al. 2001, ApJ554, 391

  4. Cumulative number of molecules detected in comets as a function of abundance relative to water RADIO Crovisier et al. 2004, A&A 418, L35

  5. Detection of ethylene glycol in comet C/1995 O1 (Hale-Bopp) together with 3 other new species (HC3N, HCOOCH3 and NH2CHO) Crovisier et al. 2004, A&A 418, L35

  6. Comparison of comets chemical composition with interstellar medium Bockelée-Morvan et al. 2000, A&A 353, 1101

  7. Progressive release of 9 molecules by comet C/1995 O1 (Hale-Bopp) - As it approached the Sun (left: 1995-1997) - As it receded from the Sun (right:1997-2001) • ALMA: • Similar monitoring in less active comets (especially investigating transition between H2O and CO sublimation dominated regimes) • Distant activity of comets: detection of CO outgassing in comets active at 5-15 AU • (mag. 16-17  QCO=51026molec./s) Biver et al. 2002, E.M.P. 90, 5

  8. ALMA and the origins (composition) of comets (from line or dust integrated fluxes) • I.1 Relative abundance of 6-8 molecules in a wide diversity of comets: • Chemical difference between Oort clouds comets and Kuiper Belt (Jupiter Family) ones? • I.2 Measuring molecular isotopic ratio: • 34S/32S, 13C/12C, 15N/14N (issue with C15N and HC15N?) in moderately bright comets, • D/H in several molecules (H2O, HCN, H2CO, NH3, CH3OH…): differs between molecules due to different enrichment process • Place of formation of nuclei and proto-planetary nebula properties • I.3 Searching for complex molecules: • ~15 only observed before in Hale-Bopp and new molecules • Origin of solar system material • I.4 Monitoring molecular and dust production rates with heliocentric distance: • Retrieving nucleus composition from abundances in the coma • Structure of cometary ices

  9. II Interferometric maps of cometary atmospheres ALMA will enable high resolution (50-100km) 3-D imaging of gas jets with simultaneous dust jets imaging and good time sampling thanks to its extensive u-v plane coverage (large number of baselines) Strong gas and dust jets in Hale-Bopp: (most of nuclear CO): determines the rotation period of 11h21m Dust jets: 75% of the near nucleus coma signal in 1P/Halley (Giotto)

  10. Rotation of a CO jet in comet Hale-Bopp: 3-D information ALMA: HCN(3-2) or HCN(4-3) in several comets

  11. Cometary « jets » with ALMA Investigating the coupling between dust and gas, and different gaseous species: Difference between night and day-time activity? Dust features predicted different from gas ones close to the nucleus? Variation of dust properties (opacity index,size distribution) with distance to the nucleus Measurement of gas (e.g. CH3OH) temperature and velocity field Interferometric maps at 90 GHz and 220 GHz comet Hale-Bopp with IRAM Plateau de Bure 9, 11, 13 and 16 March 1997: continuum of dust and nucleus Altenhoff et al. 1999, A&A 348, 1020 v

  12. Molecules coming from a distributed source in the cometary atmospheres: ALMA will be used to measure the scalelengths (100-10000 km) H2CO: ~ 80% extended: thermo-degradation of polymers? CO: ~50% extended in Hale-Bopp; HNC, OCS: extended in Hale-Bopp? CS, SO, NS?: daughter molecules; Molecules released by grain sublimation

  13. ALMA and the cometary atmospheres (interferometric mapping of physical properties) • II.1 Measuring rotation from molecular lines (e.g. HCN(3-2), strongest): • 3-D measurements thanks to the spectral resolution: rotation of several comets per year • II.2 Comparing gaseous molecular jets and dust jets close to the nucleus • Coupling of gas and dust in the near nucleus coma (sensitive to the nucleus shape), difference in day/night side activity: e.g. molecules only subliming on day side, difference in dust lifted by the gas,… • Cometary nuclei surface and gross properties (in addition to size) • II.3 Gas temperature and velocity field in the inner coma (50-1000km): • Measuring adiabatic cooling and photolytic heating, T(r), v(r) • II.4 Molecular density profiles n(r) :extended sources • Characterizing the parents (grains, other molecules, chemical reaction) of such daughter molecules: CO, H2CO, CS, SO, HNC, NS… • New parent molecules, better characterization of productions

  14. Example of observable comets for ALMA

More Related