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517 results on '"Gulkis, S."'

1. Jupiter’s interior and deep atmosphere : The initial pole-to-pole passes with the Juno spacecraft

Author

Bolton, S. J., Adriani, A., Adumitroaie, V., Allison, M., Anderson, J., Atreya, S., Bloxham, J., Brown, S., Connerney, J. E. P., DeJong, E., Folkner, W., Gautier, D., Grassi, D., Gulkis, S., Guillot, T., Hansen, C., Hubbard, W. B., Iess, L., Ingersoll, A., Janssen, M., Jorgensen, J., Kaspi, Y., Levin, S. M., Li, C., Lunine, J., Miguel, Y., Mura, A., Orton, G., Owen, T., Ravine, M., Smith, E., Steffes, P., Stone, E., Stevenson, D., Thorne, R., Waite, J., Durante, D., Ebert, R. W., Greathouse, T. K., Hue, V., Parisi, M., Szalay, J. R., and Wilson, R.

Published
2017

2. A Measurement of Anisotropy in the Cosmic Microwave Background on 7-22 Arcminute Scales

Author

Leitch, E. M., Readhead, A. C. S., Pearson, T. J., Myers, S. T., Gulkis, S., and Lawrence, C. R.

Subjects
Astrophysics
Abstract

We report a measurement of anisotropy in the cosmic microwave background radiation (CMBR) on 7-22 arcminute scales. Observations of 36 fields near the North Celestial Pole (NCP) were made at 31.7 and 14.5 GHz, using the 5.5-meter and 40-meter telescopes at the Owens Valley Radio Observatory (OVRO) from 1993 to 1996. Multi-epoch VLA observations at 8.5 and 15 GHz allow removal of discrete source contamination. After point-source subtraction, we detect significant structure, which we identify with emission from a combination of a steep-spectrum foreground and the CMBR. The foreground component is found to correlate with IRAS 100 micron dust emission. Lack of H-alpha emission near the NCP suggests that this foreground is either high-temperature thermal bremsstrahlung (T_e ~ 10^6 K), flat-spectrum synchrotron or an exotic component of dust emission. On the basis of low-frequency maps of the NCP, we can restrict the spectral index of the foreground to beta >= -2.2. Although the foreground signal dominates at 14.5 GHz, the extracted CMBR component contributes 88\% of the variance at 31.7 GHz, yielding an rms fluctuation amplitude of 82^{+12.1}_{-9.1} microKelvin, including 4.3% calibration uncertainty and 12% sample variance (68% confidence). The equivalent broadband amplitude is dT_{l_e} = 59^{+8.6}_{-6.5} microKelvin at l_e = 589. This measurement, when combined with small angular-scale upper limits obtained at the OVRO, indicates that the CMBR angular power spectrum decreases between l ~ 600 and l ~ 2000 and is consistent with flat cosmological models., Comment: Revisions to match the published version, ApJ, 532: 37-56. Latex, emulateapj.sty, 22 pages, 21 Postscript figures

Published
1998

3. MWR: Microwave Radiometer for the Juno Mission to Jupiter

Author

Janssen, M. A., Oswald, J. E., Brown, S. T., Gulkis, S., Levin, S. M., Bolton, S. J., Allison, M. D., Atreya, S. K., Gautier, D., Ingersoll, A. P., Lunine, J. I., Orton, G. S., Owen, T. C., Steffes, P. G., Adumitroaie, V., Bellotti, A., Jewell, L. A., Li, C., Li, L., Misra, S., Oyafuso, F. A., Santos-Costa, D., Sarkissian, E., Williamson, R., Arballo, J. K., Kitiyakara, A., Ulloa-Severino, A., Chen, J. C., Maiwald, F. W., Sahakian, A. S., Pingree, P. J., Lee, K. A., Mazer, A. S., Redick, R., Hodges, R. E., Hughes, R. C., Bedrosian, G., Dawson, D. E., Hatch, W. A., Russell, D. S., Chamberlain, N. F., Zawadski, M. S., Khayatian, B., Franklin, B. R., Conley, H. A., Kempenaar, J. G., Loo, M. S., Sunada, E. T., Vorperion, V., and Wang, C. C.

Published
2017
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6. MWR: Microwave Radiometer for the Juno Mission to Jupiter

Author

Janssen, M. A., primary, Oswald, J. E., additional, Brown, S. T., additional, Gulkis, S., additional, Levin, S. M., additional, Bolton, S. J., additional, Allison, M. D., additional, Atreya, S. K., additional, Gautier, D., additional, Ingersoll, A. P., additional, Lunine, J. I., additional, Orton, G. S., additional, Owen, T. C., additional, Steffes, P. G., additional, Adumitroaie, V., additional, Bellotti, A., additional, Jewell, L. A., additional, Li, C., additional, Li, L., additional, Misra, S., additional, Oyafuso, F. A., additional, Santos-Costa, D., additional, Sarkissian, E., additional, Williamson, R., additional, Arballo, J. K., additional, Kitiyakara, A., additional, Ulloa-Severino, A., additional, Chen, J. C., additional, Maiwald, F. W., additional, Sahakian, A. S., additional, Pingree, P. J., additional, Lee, K. A., additional, Mazer, A. S., additional, Redick, R., additional, Hodges, R. E., additional, Hughes, R. C., additional, Bedrosian, G., additional, Dawson, D. E., additional, Hatch, W. A., additional, Russell, D. S., additional, Chamberlain, N. F., additional, Zawadski, M. S., additional, Khayatian, B., additional, Franklin, B. R., additional, Conley, H. A., additional, Kempenaar, J. G., additional, Loo, M. S., additional, Sunada, E. T., additional, Vorperion, V., additional, and Wang, C. C., additional

Published
2017
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7. Results from the Juno MWR Instrument

Author

Levin, S.M, Janssen, M.A, Bolton, S.J, Connerney, J.E.P, Adumitroaie, V, Allison, M.D, Arballo, J.K, Atreya, S.K, Bellotti, A, Brown, S.T, Gulkis, S, Ingersoll, A.P, Li, C, Lunine, J.I, Misra, S, Orton, G.S, Oyafuso, F.A, Santos-Costa, D, Sarkissian, E, Steffes, P.G, Tabataba-Vakili, F, and Zhang, Z

Published
2018

8. Results from the Juno MWR Instrument

Author

Zhang, Z, Tabataba-Vakili, F, Steffes, P.G, Sarkissian, E, Santos-Costa, D, Oyafuso, F.A, Orton, G.S, Misra, S, Lunine, J.I, Li, C, Ingersoll, A.P, Gulkis, S, Brown, S.T, Bellotti, A, Atreya, S.K, Arballo, J.K, Allison, M.D, Adumitroaie, V, Connerney, J.E.P, Bolton, S.J, Janssen, M.A, and Levin, S.M

Abstract

UNKNOWN

Published
2018

13. Continuum and spectroscopic observations of asteroid (21) Lutetia at millimeter and submillimeter wavelengths with the MIRO instrument on the Rosetta spacecraft

Author

Gulkis, S., Keihm, S., Kamp, L., Lee, S., Hartogh, P., Crovisier, J., Lellouch, E., Encrenaz, P., Bockelee-Morvan, D., Hofstadter, M., Beaudin, G., Janssen, M., Weissman, P., von Allmen, P.A., Encrenaz, T., Backus, C.R., Ip, W.-H., Schloerb, P.F., Biver, N., Spilker, T., and Mann, I.

Published
2012
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16. Microwave observations reveal the deep extent and structure of Jupiter’s atmospheric vortices

Author

Bolton, S. J., primary, Levin, S. M., additional, Guillot, T., additional, Li, C., additional, Kaspi, Y., additional, Orton, G., additional, Wong, M. H., additional, Oyafuso, F., additional, Allison, M., additional, Arballo, J., additional, Atreya, S., additional, Becker, H. N., additional, Bloxham, J., additional, Brown, S. T., additional, Fletcher, L. N., additional, Galanti, E., additional, Gulkis, S., additional, Janssen, M., additional, Ingersoll, A., additional, Lunine, J. L., additional, Misra, S., additional, Steffes, P., additional, Stevenson, D., additional, Waite, J. H., additional, Yadav, R. K., additional, and Zhang, Z., additional

Published
2021
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20. Early Results From The Cosmic Background Explorer (COBE)

Author

Mather, J. C., Hauser, M. G., Bennett, C. L., Boggess, N. W., Cheng, E. S., Eplee, R. E., Jr., Freudenreich, H. T., Isaacman, R. B., Kelsall, T., Lisse, C. M., Moseley, S. H., Jr., Shafer, R. A., Silverberg, R. F., Spiesman, W. J., Toller, G. N., Weiland, J. L., Gulkis, S., Janssen, M., Lubin, P. M., Meyer, S. S., Weiss, R., Murdock, T. L., Smoot, G. F., Wilkinson, D. T., Wright, E. L., and Kondo, Y., editor

Published
1990
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21. Subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko

Author

Gulkis, S., Allen, M., von Allmen, P., Beaudin, G., Biver, N., Bockelée-Morvan, D., Choukroun, M., Crovisier, J., Davidsson, B. J. R., Encrenaz, P., Encrenaz, T., Frerking, M., Hartogh, P., Hofstadter, M., Ip, W.-H., Janssen, M., Jarchow, C., Keihm, S., Lee, S., Lellouch, E., Leyrat, C., Rezac, L., Schloerb, F. P., and Spilker, T.

Published
2015

22. Microwave observations reveal the deep extent and structure of Jupiter’s atmospheric vortices

Author

Bolton, S. J., Levin, S., Guillot, T., Li, C., Kaspi, Y., Orton, G., Wong, M. H., Oyafuso, F., Allison, M., Arballo, J., Atreya, S., Becker, H. N., Bloxham, J., Brown, S., Fletcher, L. N., Galanti, E., Gulkis, S., Janssen, M., Ingersoll, A., Lunine, J. L., Misra, S., Steffes, P., Stevenson, D., Waite, J. H., Yadav, R. K., Zhang, Z., Bolton, S. J., Levin, S., Guillot, T., Li, C., Kaspi, Y., Orton, G., Wong, M. H., Oyafuso, F., Allison, M., Arballo, J., Atreya, S., Becker, H. N., Bloxham, J., Brown, S., Fletcher, L. N., Galanti, E., Gulkis, S., Janssen, M., Ingersoll, A., Lunine, J. L., Misra, S., Steffes, P., Stevenson, D., Waite, J. H., Yadav, R. K., and Zhang, Z.

Abstract

Jupiter’s atmosphere has a system of zones and belts punctuated by small and large vortices, the largest being the Great Red Spot. How these features change with depth is unknown, with theories of their structure ranging from shallow meteorological features to surface expressions of deep-seated convection. We present observations of atmospheric vortices using the Juno spacecraft’s Microwave Radiometer. We find vortex roots that extend deeper than the altitude at which water is expected to condense, and identify density inversion layers. Our results constrain the 3-dimensional structure of Jupiter’s vortices and their extension below the clouds.

Published
2021

23. MIRO: Microwave Instrument for Rosetta Orbiter

Author

Gulkis, S., Frerking, M., Crovisier, J., Beaudin, G., Hartogh, P., Encrenaz, P., Koch, T., Kahn, C., Salinas, Y., Nowicki, R., Irigoyen, R., Janssen, M., Stek, P., Hofstadter, M., Allen, M., Backus, C., Kamp, L., Jarchow, C., Steinmetz, E., Deschamps, A., Krieg, J., Gheudin, M., Bockelée-Morvan, D., Biver, N., Encrenaz, T., Despois, D., Ip, W., Lellouch, E., Mann, I., Muhleman, D., Rauer, H., Schloerb, P., and Spilker, T.

Published
2007
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24. Deep Impact: observations from a worldwide earth-based campaign

Author

Meech, K.J., Ageorges, N., A'Hearn, M.F., Arpigny, C., Ates, A., Aycock, J., Bagnulo, S., Bailey, J., Barber, R., Barrera, L., Barrena, R., Bauer, J.M., Belton, M.J.S., Bensch, F., Bhattacharya, B., Biver, N., Blake, G., Bockelee-Morvan, D., Boehnhardt, H., Bonev, B.P., Bonev, T., Buie, M.W., Burton, M.G., Butner, H.M., Cabanac, R., Campbell, R., Campins, H., Capria, M.T., Carroll, T., Chaffee, F., Charnley, S.B., Cleis, R., Coates, A., Cochran, A., Colom, P., Conrad, A., Coulson, I.M., Crovisier, J., deBuizer, J., Dekany, R., de Leon, J., Russo, N. Dello, Delsanti, A., DiSanti, M., Drummond, J., Dundon, L., Etzel, P.B., Farnham, T.L., Feldman, P., Fernandez, Y.R., Filipovic, M.D., Fisher, S., Fitzsimmons, A., Fong, D., Fugate, R., Fujiwara, H., Fujiyoshi, T., Furusho, R., Fuse, T., Gibb, E., Groussin, O., Gulkis, S., Gurwell, M., Hadamcik, E., Hainaut, O., Harker, D., Harrington, D., Harwit, M., Hasegawa, S., Hergenrother, C.W., Hirst, P., Hodapp, K., Honda, M., Howell, E.S., Hutsemekers, D., Iono, D., Ip, W.-H., Jackson, W., Jehin, E., Jiang, Z.J., Jones, G.H., Jones, P.A., Kadono, T., Kamath, U.W., Kaufl, H.U., Kasuga, T., Kawakita, H., Kelley, M.S., Kerber, F., Kidger, M., Kinoshita, D., Knight, M., Lara, L., Larson, S.M., Lederer, S., Lee, C.-F., Levasseur-Regourd, A.C., Li, J.Y., Li, Q.-S., Licandro, J., Lin, Z.-Y., Lisse, C.M., LoCurto, G., Lovell, A.J., Lowry, S.C., Lyke, J., Lynch, D., Ma, J., Magee-Sauer, K., Maheswar, G., Manfroid, J., Marco, O., Martin, P., Melnick, G., Miller, S., Miyata, T., Moriarty-Schieven, G.H., Moskovitz, N., Mueller, B.E.A., Mumma, M.J., Muneer, S., Neufeld, D.A., Ootsubo, T., Osip, D., Pandea, S.K., Pantin, E., Paterno-Mahler, R., Patten, B., Penprase, B.E., Peck, A., Petitas, G., Pinilla-Alonso, N., Pittichova, J., Pompei, E., Prabhu, T.P., Qi, C., Rao, R., Rauer, H., Reitsema, H., Rodgers, S.D., Rodriguez, P., Ruane, R., Ruch, G., Rujopakarn, W., Sahu, D.K., Sako, S., Sakon, I., Samarasinha, N., Sarkissian, J.M., Saviane, I., Schirmer, M., Schultz, P., Schulz, R., Seitzer, P., Sekiguchi, T., Selman, F., Serra-Ricart, H., Sharp, R., Snell, R.L., Snodgrass, C., Stallard, T., Stecklein, G., Sterken, C., Stuwe, J.A., Sugita, S., Sumner, M., Suntzeff, N., Swaters, R., Takakuwa, S., Takato, N., Thomas-Osip, J., Thompson, E., Tokunaga, A.T., Tozzi, G.P., Tran, H., Troy, M., Trujillo, C., Van Cleve, J., Vasundhara, R., Vazquez, R., Vilas, F., Villanueva, G., von Braun, K., Vora, P., Wainscoat, R.J., Walsh, K., Watanabe, J., Weaver, H.A., Weaver, W., Weiler, M., Weissman, P.R., Welsh, W.F., Wilner, D., Wolk, S., Womack, M., Wooden, D., Woodney, L.H., Woodward, C., Wu, Z.-Y., Wu, J.-H., Yamashita, T., Yang, B., Yang, Y.-B., Yokogawa, S., Zook, A.C., Zauderer, A., Zhao, X., Zhou, X., and Zucconi, J.-M.

Subjects
Tempel 1 comet -- Observations -- Research, Earth -- Research, Science and technology
Abstract

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics., The Deep Impact mission was designed so that much of the mission-critical science would be done from Earth-based telescopes. These facilities would observe the comet before, during, and after impact [...]

Published
2005

25. Microwave remote sensing of Jupiter's atmosphere from an orbiting spacecraft

Author

Janssen, M.A., Hofstadter, M.D., Gulkis, S., Ingersoll, A.P., Allison, M., Bolton, S.J., Levin, S.M., and Kamp, L.W.

Subjects
Radiative transfer -- Research, Atmosphere -- Research, Jupiter (Planet) -- Research, Jupiter (Planet) -- Observations, Jupiter (Planet) -- Discovery and exploration, Earth -- Atmosphere, Earth -- Research, Astronomy, Earth sciences
Abstract

Microwave remote sounding from a spacecraft flying by or in orbit around Jupiter offers new possibilities for retrieving important and presently poorly understood properties of its atmosphere. In particular, we show that precise measurements of relative brightness temperature as a function of off-nadir emission angles, combined with absolute brightness temperature measurements, can allow us to determine the global abundances of water and ammonia and study the dynamics and deep circulations of the atmosphere in the altitude range from the ammonia cloud region to depths greater than 30 bars in a manner which would not be achievable with ground-based telescopes. Keywords: Jupiter atmosphere; Abundances, interior; Radio observations; Radiative transfer

Published
2005

26. MIRO: Microwave Instrument for Rosetta Orbiter

Author

Gulkis, S., primary, Frerking, M., additional, Crovisier, J., additional, Beaudin, G., additional, Hartogh, P., additional, Encrenaz, P., additional, Koch, T., additional, Kahn, C., additional, Salinas, Y., additional, Nowicki, R., additional, Irigoyen, R., additional, Janssen, M., additional, Stek, P., additional, Hofstadter, M., additional, Allen, M., additional, Backus, C., additional, Kamp, L., additional, Jarchow, C., additional, Steinmetz, E., additional, Deschamps, A., additional, Krieg, J., additional, Gheudin, M., additional, Bockelée-Morvan, D., additional, Biver, N., additional, Encrenaz, T., additional, Despois, D., additional, Ip, W., additional, Lellouch, E., additional, Mann, I., additional, Muhleman, D., additional, Rauer, H., additional, Schloerb, P., additional, and Spilker, T., additional

Published
2009
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27. Ultra-relativistic electrons in Jupiter's radiation belts

Author

Bolton, S. J., Janssen, M., Thorne, R., Levin, S., Klein, M., Gulkis, S., Bastian, T., Sault, R., Elachi, C., Hofstadter, M., Bunker, A., Dulk, G., Gudim, E., Hamilton, G., Johnson, W. T. K., Leblanc, Y., Liepack, O., McLeod, R., Roller, J., Roth, L., and West, R.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): S. J. Bolton (corresponding author) [1]; M. Janssen [1]; R. Thorne [2]; S. Levin [1]; M. Klein [1]; S. Gulkis [1]; T. Bastian [3]; R. Sault [4]; C. Elachi [...]

Published
2002
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28. Regolith Properties of Asteroid 21 Lutetia Constrained by Combined Data Sets of the MIRO and VIRTIS Instruments During the Rosetta Spacecraft Flyby

Author

Keihm, S, Tosi, F, Kamp, L, Capaccioni, F, Grassi, D, Gulkis, S, and Coradini, A

Subjects
Lunar And Planetary Science And Exploration
Abstract

During the July 10, 2010 flyby of Asteroid 21 Lutetia by the Rosetta spacecraft, maps of surface and subsurface temperatures were derived from the VIRTIS and MIRO instruments respectively. Both data sets indicated a porous surface layer with an extremely low, lunar-like thermal inertia. However, comparisons of the VIRTIS-measured and MIRO-modelled surface temperatures revealed offsets of 10- 30 K, indicative of self-heating or "beaming" effects that were not taken into account in the MIRO thermal modeling. Inclusion of a model of hemispherical craters at all scales 1 cm and larger, covering 50% of the surface, removes most of the offsets in the VIRTIS, MIRO surface temperature determinations.

Published
2011

29. The U.S. Rosetta Project at Its First Science Target: Asteroid (2867) Steins, 2008

Author

Alexander, C, Sweetnam, D, Gulkis, S, Weissman, P, Holmes, D, Parker, J, Burch, J, Goldstein, R, Mokashi, P, Fuselier, S, and McFadden, L

Subjects
Lunar And Planetary Science And Exploration, Solar Physics, Instrumentation And Photography
Abstract

On September 5, 2008, the International Rosetta Mission encountered its first formal science target of the mission, asteroid (2867) Steins. We report preliminary results from the U.S. experiments. NASA's contribution to the Rosetta mission consists of an ultraviolet (UV) spectrometer, a microwave spectrometer, a plasma instrument, and a portion of the electronics package for a mass spectrometer. The UV spectrometer (Alice) was used to obtain the first far-ultraviolet (FUV) spectrum of an asteroid. A ten-minute integration, surrounding the time of closest approach, averaging over a variety of geometries, showed very good signal from 850 Angstroms to 2000 Angstroms in the FUV. The microwave instrument (MIRO) obtained a high signal to noise measurement at both observing frequencies, enabling key thermal parameters to be derived. The plasma instrument (IES) obtained a brief measurement of the solar wind, and the Double Focusing Mass Spectrometer (DFMS) of the ROSINA instrument obtained a signal just at closest approach. Laboratory work with analogue materials was begun.

Published
2010

30. Long-term monitoring of the outgassing and composition of comet 67P/Churyumov-Gerasimenko with the Rosetta/MIRO instrument

Author

Biver, Nicolas, Bockelée-Morvan, D., Hofstadter, M., Lellouch, E., Choukroun, M., Gulkis, S., Crovisier, J., Schloerb, F, Rezac, L., von Allmen, P, Lee, S., Leyrat, C., Ip, W., Hartogh, P., Encrenaz, P., Beaudin, Gérard, The Miro Team, And, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, University of Massachusetts [Amherst] (UMass Amherst), University of Massachusetts System (UMASS), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), National Central University, Taiwan, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), NASA-California Institute of Technology (CALTECH), JPL - Jet Propulsion Laboratory, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), and Crovisier, Jacques

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

Accepted for publication in Astronomy & Astrophysics; We present the analysis of ≈100 molecular maps of the coma of comet 67P/Churyumov-Gerasimenko obtained with the MIRO submillimeter radio telescope on board the Rosetta spacecraft. From the mapping of spectral lines of H 16 2 O, H 18 2 O, H 17 2 O, CH 3 OH, NH 3 and CO, and some fixed nadir pointings, we retrieved the outgassing pattern and total production rate for these species. The analysis covers the period from July 2014, inbound to perihelion, to June 2016, outbound, and heliocentric distances r h =1.24 to 3.65 AU. A steep evolution of the outgassing rates with heliocentric distance is observed, typically in r −6 h , with significant differences between molecules (e.g. steeper variation for H 2 O post perihelion than for methanol). As a consequence the abundances relative to water in the coma vary. The CH 3 OH and CO abundances increase after perihelion while the NH 3 abundance peaks around perihelion and decreases after. Outgassing patterns have been modeled as 2-D Gaussian "jets". The width of these jets is maximum around the equinoxes when the bulk of the outgassing is located near the equator. From July 2014 to Feb. 2015 the outgassing is mostly restricted to a narrower jet (Full Width at Half Maximum, FWHM ≈80 •) originating from high northern latitudes, while around perihelion most of the gaseous production comes from the southernmost regions (−80±5 • cometocentric latitude) forming a 100-130 • (FWHM) wide fan. We find a peak production of water of 0.8 × 10 28 molec. s −1 , 2.5 times smaller than measured by the ROSINA experiment, and put an upper limit to a 50% additional production that could come from the sublimation of icy grains. We estimate the total loss of ices during this perihelion passage to 4.18 ± 0.18 × 10 9 kg. We derive a dust-togas ratio in the lost material of 0.7 to 2.3 (including all sources of errors), based on the nucleus mass loss of 10.5 ± 3.4 × 10 9 kg estimated by the RSI experiment. We also obtain an estimate of the H 18 2 O/H 17 2 O ratio of 5.6 ± 0.8.

Published
2019

31. The thermal profile and water abundance in the Venus mesosphere from H2O and HDO millimeter observations

Author

Encrenaz, Th., Lellouch, E., Cernicharo, J., Paubert, G., Gulkis, S., and Spilker, T.

Subjects
Venus (Planet) -- Atmosphere, Astronomy, Earth sciences
Abstract

The mean level of H2O over the clouds of Venus' upper atmosphere is less than 12 ppm, low as compared to the day-side results obtained in earlier observations. The mesospheric temperature is found to be around 140 K at an altitude level z = 95 km. The water content varies throughout the year and temperature also is subject to temporal fluctuations. These results are obtained from the observations made on the spectral lines of H2O and HDO transitions in the Venus atmosphere.

Published
1995

32. Outburst of Jupiter's synchrotron radiation after the impact of Comet Shoemaker-Levy 9

Author

de Pater, Imke, Heiles, C., Wong, M., Maddalena, R.J., Bird, M.K., Funke, O., Neidhoefer, J., Price, R.M., Kesteven, M., Calabretta, M., Klein, M.J., Gulkis, S., Bolton, S.J., Foster, R.S., Sukumar, S., Strom, R.G., LePoole, R.S., Spoelstra, T., Robison, M., Hunstead, R.W., Campbell-Wilson, D., Ye, T., Dulk, G., Leblanc, Y., Galopeau, P., Gerard, E., and Lecacheux, A.

Subjects
Synchrotron radiation sources -- Observations, Jupiter (Planet) -- Observations, Shoemaker-Levy 9 (Comet) -- Observations, Science and technology, Observations
Abstract

Jupiter's nonthermal microwave emission, as measured by a global network of 11 radio telescopes, increased dramatically during the Shoemaker-Levy 9 impacts. The increase was wavelength-dependent, varying from ~10 percent at 70 to 90 centimeters to ~45 percent at 6 and 36 centimeters. The radio spectrum hardened (flattened toward shorter wavelengths) considerably during the week of impacts and continued to harden afterward. After the week of cometary impacts, the flux density began to subside at all wavelengths and was still declining 3 months later. Very Large Array and Australia Telescope images of the brightness distribution showed the enhancement to be localized in longitude and concentrated near the magnetic equator. The evidence therefore suggests that the increase in flux density was caused by a change in the resident particle population, for example, through an energization or spatial redistribution of the emitting particles., A worldwide network of radio telescopes was organized to observe jupiter's flux density at microwave frequencies before, during, and after comet Shoemaker-Levy 9 (SL9) collided with the planet in July [...]

Published
1995

33. A tentative detection of the 183-GHz water vapor line in the Martian atmosphere: constraints upon the H2O abundance and vertical distribution

Author

Encrenaz, Th., Lellouch, E., Cernicharo, J., Paubert, G., and Gulkis, S.

Subjects
Mars (Planet) -- Atmosphere, Astronomy, Earth sciences
Abstract

The observation of the 183-gigahertz water vapor line on planet Mars, using IRAM 30-meter millimeter antenna reveals the abundance of water molecules in the atmosphere of Mars. The observations are performed under dry atmospheric conditions, and the measurements apply to the whole disk of the planet. The spectral line, though marginal, can be fitted into the existing model with a constant H2O mixing ratio of 1/100,000.

Published
1995

35. A polar orbiter to probe Jupiter's deep atmosphere, interior structure and polar magnetosphere

Author

Bolton, S. J, Allison, M, Anderson, J, Atreya, S, Bagenal, F, Connerney, J, Coradini, A, DeJong, E, Folkner, W, Gautier, D, Gladstone, R, Gulkis, S, Guillot, T, Hofstadter, M, Hubbard, W, Ingersoll, A, Janssen, M, Klein, M, Kurth, W, Levin, S, Lunine, J, Mauk, B, McComas, D, Murphy, N, Owen, T, Smith, E, Spilker, T, Stevenson, D, Thorne, R, and Waite, H

Published
2003

47. Divine-garrett model and Jovian synchrotron emission

Author

Bolton, S, Levin, S, Gulkis, S, Klein, M, Sault, R, Bhattacharya, B, Thorne, R, Dulk, G, and Leblanc, Y

Subjects
Geophysics
Abstract

Simulations of synchrotron emission from relativistic electrons trapped in Jupiter's magnetic field are used to evaluate the energetic electron distribution of the Divine-Garrett Jupiter radiation belt model at radial distances less than 4 Jovian radii.

Published
2001

48. Modeling Jupiter's synchrotron radiation

Author

Levin, S, Bolton, S, Gulkis, S, Klein, M, Bhattacharya, B, and Thorne, R

Subjects
Lunar And Planetary Science And Exploration
Abstract

We have constructed a computer model to simulate synchrotron emission from relativistic electrons trapped in Jupiter's magnetic field.

Published
2001

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