Observation of OH in Beta Pictoris exocomets
Abstract
The Beta Pictoris system is a young planetary system embedded in a debris disk that is continually replenished by the collision and evaporation of planetesimals and exocomets. As a result of the edge-on inclination of the debris disk, transiting exocomets can be observed in great detail using absorption spectroscopy. Our previous COS observations yielded the first detection of exocomets in the far-UV, with the discovery of several new exocometary species including HI, CII, NI, OI and several ionization states of Si. Interestingly, the C/O ratio in the exocomets seems to also distinguish the two dynamically different exocomet populations known to exist in the Beta Pictoris system.
Here we propose to search for OH variable absorptions at 3085 Ang. to measure the abundance of water and to identify if water is the key volatile in the exocomets of Beta Pictoris. Positive detections of OH in the exocomets would be the first indirect discovery of water in the Beta Pictoris disk. Moreover, we will investigate the possibility that the two dynamically different exocomet populations have different compositions and origins. These objectives can be achieved by the acquisition of STIS Echelle spectra at different epochs. Measuring the abundance of OH and the OH/Mg ratio in the Beta Pic evaporating exocomets will enable us to trace the condensation and evaporation processes and their location in the late stages of planetary formation. This will provide valuable insights into the origins of the exocomets of the Beta Pictoris system.- Publication:
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HST Proposal
- Pub Date:
- June 2016
- Bibcode:
- 2016hst..prop14735K