OSIRIS Observations of Comet 2004/Q2 Machholz Miriam Rengel MPS, Germany Titelseite Jones G. , Küppers M., Keller H.U., Hviid S. MPS, Germany MPS, Germany MPS, Germany MPS, Germany 7/11/2006 NASA/JPL-Caltech/UMD

Rosetta Orbiter Instruments OSIRIS: Scientific cameras onboard Rosetta Cameras Optical, Spectroscopic, and Infrared Remote Imaging System P.I : Horst Uwe Keller, MPS (Germany) NAC During commisioning Machholz was observed for around 3 hours on 20th January 2005. 7/11/2006

Machholz trajectory with respect to fixed Sun-Earth line Ecliptic Plane C/2004 Q2 (Machholz) in an orbit that kept it relatively close to Earth throughout its perihelion passage. Distance Earth-comet= 0.405 AU Figure shows motion of comet with respect to fixed Sun-Earth line. Excellent orbit for comparing comet ion tail structures with near-Earth solar wind data. Perihelion at 1.205 AU Comet on January 20th 0.35 AU from Earth 7/11/2006

Goals To analyse the OSIRIS observations of 2004/Q2 Machholz To investigate the ion tail orientation/appearance in the OSIRIS observations in order to provide indications of the solar wind velocity at the comet To construct an anaglyph with OSIRIS-Earth- based observations to get a quantitative assesment of the 3D vector of the solar wind 7/11/2006

How? Ingredients 7/11/2006

Observations of 2004/Q2 Machholz Narrow Angle Camera (NAC) Pixel scale at the comet 1: 1247 km Filters used: 4 medium bandwidth filters at 648 – 980 nm Wide Angle Camera (WAC) Pixel scale: 5962 km Filters: red continuum, green, UV375, CN, CH, CS, and UV245 Observations Start: 19:54 UT on 20. January 2005 End: 23:01 UT on 20. January 2005 Total number of images: 75 Exposure time: 20 and 60 s Best time resolution: ca. 1 image per minute Stereo angle Rosetta-Machholz – Earth 14º 7/11/2006

Example of images: NAC NAC Orange filter NAC Green filter NAC Blue filter NAC Red filter 649 nm 536 nm 481 nm 744 nm 7/11/2006

WAC red broadband green UV375 CN 376 nm 630 nm 537 nm 388 nm CS UV245 CH 7/11/2006 309 nm 259 nm 246 nm

Emission of ion tail detected with the WAC red & green filters High number of signatures of cosmic rays Algorithm for rejecting cosmic-rays: L.A.Cosmic P. G. van Dokkum, 2001, PASP, 113, 1420 7/11/2006

False Color Composite OSIRIS Image of Comet 2004/Q2 Machholz Visible Ion tail of Lenght of > 200000 km (H2O+) Its orientation remains a valuable method for inferring solar wind velocities 7/11/2006 WAC Red

Model of solar wind conditions Modeled Solar wind conditions at Machholz Solar wind conditions at comet’s orbit modelled using MHD simulation based on solar observations of photosphere. (Matt Owens, Boston University) Solar wind data obtained from OSIRIS observations can be compared to model, and to ACE near-Earth solar wind data. 7/11/2006

ACE near-Earth solar wind conditions indicate that January 20th was a period when several CMEs reached Earth, and hence also Machholz. 7/11/2006

Preliminary results Solar-wind speed and orbital motion causes plasma tail to point several degrees away from the radius vector Schematic showing the aberration effect and the orientation of plasma tails. Courtesy: J. Brandt Plasma tail would point : very close to the anti-solar direction for a very high solar-wind speed (750 km/s) and larger angle for a v of 450 m/s. 7/11/2006

Results Plasma tail points very close to the anti-solar direction  high solar-wind speed (~750 km/s). WAC Red 7/11/2006 Anti-solar direction

Results We do not detected with OSIRIS propagating disturbances in the ion tail in the temporal sequence, neither disconnection events or knots: we do not identify CME signatures The comet appears to be immersed in a fast, steady coronal hole flow 7/11/2006

Ground-based observations Survey of amateur images of Machholz being conducted by Geraint Jones (MPS) and Jack Brandt (University of New Mexico). Extensive collection of amateur images collected. Sequence at left shows rapid change of ion tail in response to arrival of a coronal mass ejection at the comet on January 18, 2005, 2 days before OSIRIS observations. 7/11/2006

Mike Holloway Van Buren, Arkansas January 19, 00:46 UT

Masaaki Uto, Itawa, Japan January 20 2005, 11:40 UT 7/11/2006

Isao Ootsuki (Miyagi, Japan) 2005 Jan. 21 13:32 UT

Mike Holloway Van Buren, Arkansas January 21, 02:14 UT 7/11/2006

Earth from Machholz during the OSIRIS ion tail observations (20:42 on 2005 January 20) Extensive cloud cover over northern Europe, but Italy, Spain clear. Moon ¾ full. No images taken during OSIRIS observations located so far. 7/11/2006

...we can recostruct the 3D velocity vector Nevertheless....if solar wind direction does not change significantly in few hours.... ...we can recostruct the 3D velocity vector Observations: Same resolution Consider comet‘s orbital motion Two problems of Stereo: Correspondence Reconstruction Non-parallel cameras 14 degrees 0.4 AU 0.405 AU 7/11/2006

Results Original resolutions: Arkansas:2159,4 km/pixel WAC: 5961,7 km/pixel WAC OSIRIS Arkansas image Half-colour Colour 7/11/2006 Stereo-imaging

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Plans *Improve stereo images Schematic of stereo imaging setup   *Improve stereo images If you have/know Machholz Earth-based observations taken around 21 UT on 20th January 2005 Please let me know it! *construct the epipolar geometry - to perform the 3D reconstruction by triangulation * Compare the results with the available modeled Solar wind conditions                                                                                   7/11/2006

OSIRIS Publications & Proceedings Rengel, M. , Kueppers, M.; Keller, H. U.; Gutierrez, P.; Hviid, S. "A Study of the Velocities of the Ejected Dust and of the Rotational Variability of Comet 9P/Tempel 1 around the Deep Impact Event ". American Astronomical Society, DPS meeting 38, 17.06. California, USA, October 2006. H.U. Keller, M. Rengel , M. Kueppers, P. Gutierrez and S. Lowry "Monitoring of Comet 9P/Tempel 1 around the Deep Impac event with the OSIRIS NACCamera ". IAU XXVIth General Assembly, Prague, Chezk Republic, August 14-25,2006. M. Rengel , M. Kueppers, H.U. Keller, and P. Gutierrez. "Modeling of the Terminal Velocities of the Dust Ejected Material by the Impact ". Deep Impact as a World Observatory Event - Synergies in Space, Time, and Wavelength, Brussels, Belgium, 7-10 August 2006. Proceedings in the ESO / SPRINGER series (eds. Ulli Käufl & Chris Sterken). H.U. Keller, M. Kueppers, M Rengel , S. Fornasier, G. Cremonese, P. Gutierrez, W. H. Ip, J. Knollenberg, L. Jorda "Observations of comet 9P/Tempel 1 around the Deep Impact event with the OSIRIS cameras on Rosetta". The 36th COSPAR Scientific Assembly, Beijing, China, 16-13 July 2006. Rengel M., Küppers, M.; Keller, H. U.; Gutierrez, P. "Analysing the Post Deep Impact Brightness distribution of the Cometary Dust of the Comet 9P/Tempel 1 with OSIRIS". General Assembly of the European Geosciences Union, Vienna, Austria, April 2-7, 2006. Horst Uwe Keller, Michael Küppers, Sonia Fornasier , Pedro J. Gutierrez, Stubbe F. Hviid, Laurent Jorda, Jörg Knollenberg, Stephen C. Lowry, Miriam Rengel, et al. "Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta". Special issue of Icarus on the Deep Impact mission (accepted). http://www.mps.mpg.de/homes/rengel/ http://www.mps.mpg.de/en/projekte/rosetta/osiris/ DI will continue to produce new results! END 7/11/2006

Next Slides Possible questions Possible answers 7/11/2006

Geometry for comet Machholz on 20-Jan-2005 22 UT: Heliocentric distance of the comet: 1.207 Geocentric distance of the comet: 0.405 Distance Comet-Rosetta: 0.443 Distance Earth-Rosetta: 0.110 Heliocentric distance of Rosetta: 1.069 Solar elongation of the comet as seen from Rosetta: 97.1 Phase angle of the comet as seen from Rosetta: 61.5 Phase angle of the comet from the Earth: 48.2 Angle between the Earth and Rosetta as seen from the comet: 14.0 Heliocentric velocity of the comet: -1.4 Geocentric velocity of the comet: 11.8 Distances in AU, Angles in degrees, velocities in km/s 7/11/2006