VARIATION IN THE PRE-TRANSIT BALMER LINE SIGNAL AROUND THE HOT JUPITER HD 189733B
AffiliationUniv Arizona, Dept Planetary Sci
Univ Arizona, Lunar & Planetary Lab
Keywordsplanets and satellites
planets and satellites
planets and satellites
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationVARIATION IN THE PRE-TRANSIT BALMER LINE SIGNAL AROUND THE HOT JUPITER HD 189733B 2016, 152 (1):20 The Astronomical Journal
JournalThe Astronomical Journal
Rights© 2016. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractAs followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full pre-transit phase coverage of a single planetary transit. The pre-transit signal is again detected in the Balmer lines but with variable strength and timing, suggesting that the bow shock geometry reported in our previous work does not describe the signal from the latest transit. We also demonstrate the use of the Ca II H and K residual core flux as a proxy for the stellar activity level throughout the transit. A moderate trend is found between the pre-transit absorption signal in the 2013 data and the Ca II H flux. This suggests that some of the 2013 pre-transit hydrogen absorption can be attributed to varying stellar activity levels. A very weak correlation is found between the Ca II H core flux and the Balmer line absorption in the 2015 transit, hinting at a smaller contribution from stellar activity compared to the 2013 transit. We simulate how varying stellar activity levels can produce changes in the Balmer line transmission spectra. These simulations show that the strength of the 2013 and 2015 pre-transit signals can be reproduced by stellar variability. If the pre-transit signature is attributed to circumplanetary material, its evolution in time can be described by accretion clumps spiraling toward the star, although this interpretation has serious limitations. Further high-cadence monitoring at H alpha is necessary to distinguish between true absorption by transiting material and short-term variations in the stellar activity level.
VersionFinal published version
SponsorsNASA Keck PI Data Award; W.M. Keck Foundation; National Science Foundation through Astronomy and Astrophysics Research Grant [AST-1313268]