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Your search keyword '"Alessondra Springmann"' showing total 3 results
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3 results on '"Alessondra Springmann"'

1. Ice, Ice, Maybe? Investigating 46P/Wirtanen’s Inner Coma for Icy Grains

Author

Theodore Kareta, John W. Noonan, Walter M. Harris, and Alessondra Springmann

Subjects
Comae, Comet nuclei, Comet volatiles, Short period comets, Ice composition, Astronomy, QB1-991
Abstract

The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyperactive comets other sources have to be considered to account for the total production rates. In this work, we present new near-IR (NIR) imaging and spectroscopic observations of 46P/Wirtanen taken during its close approach to Earth on 2018 December 19 with the MMIRS instrument at the MMT Observatory to search for signatures of icy or ice-rich grains in its inner coma that might explain its previously reported excess water production. The morphology of the images does not suggest any change in grain properties within the field of view, and the NIR spectra do not show the characteristic absorption features of water ice. Using a new Markov Chain Monte Carlo–based implementation of the spectral modeling approach of Protopapa et al., we estimate the areal water ice fraction of the coma to be

Published
2023
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3. Size and Shape of (11351) Leucus from Five Occultations

Author

John Keller, Dale R. Stanbridge, Jerry E. Bardecker, Christopher B. Lundgren, Beatrice E. A. Mueller, Michael P. von Schalscha, Marc W. Buie, Joan B. Dunham, Alex D. Rolfsmeier, Roxanne L. Kamin, Rima M. Givot, Joshua A. Kammer, Jack Lee Jewell, Bryan Hill, Yamir Hernandez, William H. Hanna, Ted E. Blank, Kai Getrost, Brian A. Keeney, Andrew E. McCandless, Michael Collins, Lawrence H. Wasserman, Timothy J Stoffel, Franck Marchis, Ryder Strauss, Aart M. Olsen, Joseph I. Samaniego, John R. Spencer, Julien Salmon, Alessondra Springmann, Cecilia W. S. Leung, James G. Rigby, Daniel O’Conner Peluso, T. Gialluca Megan, Robert L. Marcialis, Robert Weryk, John G. Moore, David A. Kenyon, Kelly E. Miller, John A. Eaccarino, Anne J. Verbiscer, Qicheng Zhang, P. C. Hinton, Hugh M. Davidson, Timothy R. Holt, J. N. Kidd, Scott R. Kester, John Noonan, Michael E. Brown, Catherine B. Olkin, Maria L. Garcia, Michael F. Skrutskie, R. P. Sawyer, Tiffany J. Finley, Holly Werts, Delsie Joy McCrystal, Tod R. Lauer, Alexander R. Patton, Zoey R. Lorusso, David W. Dunham, Gregory J. Kayl, Peter Tamblyn, David Gupton, Lindsay Fuller, Tony George, Harold F. Levison, Theodore Kareta, P. D. Maley, Rodrigo Leiva, Carl Hergenrother, Simon B. Porter, Robert R. Howell, Rose J. C. Smith, Lilah B Brown, David M. Schulz, Bryan Tobias, L. O. Magana, and A. M. McGraw

Subjects
Geophysics, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Astronomy, Stellar occultation, Astronomy and Astrophysics, Astrometry, Geology
Abstract

We present observations of five stellar occultations for (11351) Leucus and reports from two efforts on (21900) Orus. Both objects are prime mission candidate targets for the Lucy Discovery mission. Combined results for Leucus indicate a very dark surface with p V = 0.037 ± 0.001, which is derived from the average of the multichord occultations. Our estimate of the triaxial ellipsoidal shape is for axial diameters of 63.8 × 36.6 × 29.6 km assuming that the spin pole is normal to the line of sight. The actual shape of the object is only roughly elliptical in profile at each epoch. Significant topography is seen with horizontal scales up to 30 km and vertical scales up to 5 km. The most significant feature is a large depression on the southern end of the object as seen from a terrestrial viewpoint. For this work we developed a method to correct for differential refraction, accounting for the difference in color between the target object and the reference stars for astrometry derived from ground-based images.

Published
2021
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