Open AccessNeutral Sodium from Comet Hale-Bopp: A Third Type of Tail
Author(s) -
G. Cremonese,
H. Boehnhardt,
J. Crovisier,
H. Rauer,
A. Fitzsimmons,
M. Fulle,
J. Licandro,
D. Pollacco,
G. P. Tozzi,
R. M. West
Publication year - 1997
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/311040
Subject(s) - comet , photoionization , sodium , physics , line (geometry) , chemistry , ion , energetic neutral atom , fluorescence , atomic physics , astrophysics , ionization , optics , organic chemistry , geometry , mathematics , quantum mechanics
We report on the discovery and analysis of a striking neutral sodium gas tailassociated with comet C/1995 O1 Hale-Bopp. Sodium D-line emission has beenobserved at heliocentric distance r<1.4 AU in some long-period comets and thepresence of neutral sodium in the tailward direction of a few bright comets hasbeen noted, but the extent, and in particular the source, has never been clear.Here we describe the first observations and analysis of a neutral sodium gastail in comet Hale-Bopp, entirely different from the previously known ion anddust tails. We show that the observed characteristics of this third type oftail are consistent with itbeing produced by radiation pressure due toresonance fluorescence of sodium atoms and that the lifetime forphotoionization is consistent with recent theoretical calculation.Comment: 10 pages, 3 figures, it will pubblished on A.P.J. Lette
Accelerating Research
Robert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom
Address
John Eccles HouseRobert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom