J/A+A/619/A96 HD189733 spectral variability (Kohl+, 2018)
HD 189733b: bow shock or no shock?
Kohl S., Salz M., Czesla S., Schmitt J.H.M.M.
<Astron. Astrophys. 619, A96 (2018)>
=2018A&A...619A..96K 2018A&A...619A..96K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Equivalent widths
Keywords: planets and satellites: atmospheres -
planets and satellites: gaseous planets -
planets and satellites: individual: HD 189733
Abstract:
Hot Jupiters are surrounded by extended atmospheres of neutral
hydrogen. Observations have provided evidence for in-transit hydrogen
Hα absorption as well as variable pre-transit absorption
signals. These have been interpreted in terms of a bow shock or an
accretion stream that transits the host star before the planet.
We test the hypothesis of planetary related Hα absorption by
studying the time variability of the Hα and stellar
activity-sensitive calcium lines in high-resolution spectra of the
planet host HD189733.
In the framework of an observing campaign spanning several months, the
host star was observed several times per week randomly sampling the
orbital phases of the planet.
We determine the equivalent width in the Hα, Ca H&K and Ca IRT
lines, and subtract stellar rotationally induced activity from the
Hα time series via its correlation with the IRT evolution.
The residuals are explored for significant differences between the
pre-, in-, and out-of-transit phases.
We find strong stellar rotational variation with a lifetime of about
20-30 days in all activity indicators, but the corrected Hα time
series exhibits no significant periodic variation. We exclude the
presence of more than 6.2mÅA pre-transit absorption and 5.6mÅ
in-transit absorption in the corrected Hα data at a 99%
confidence level.
Previously observed Hα absorption signals exceed our upper
limits, but they could be related to excited atmospheric states. The
Hα variability in the HD189733 system is dominated by stellar
activity, and observed signals around the planetary transit may well
be caused by short term stellar variability.
Description:
Table 2 contains the observed excess equivalent width in different
lines for each individual observation of HD189733.
This data was used to search for planet-induced absorption signals.
Each single observation has been corrected for telluric absorption.
To obtain the excess flux we subtract the template HD 10476 from our
HD 189733 observations. The integration bands are centered on the line
cores. The widths are 2Å in Hα and 1.5Å in the other
lines.
The spectra have been acquired at the 1.2m Tigre telescope located in
La Luz, Mexico. The spectral resolution of the HEROS spectrograph is
20000.
A detailed description of the table is given in the paper.
Objects:
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RA (2000) DE Designation(s)
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20 00 43.7 +22 42 39 HD 189733 = V* V452 Vul
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 72 108 HD189733 excess equivalent width in different lines
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.1 d BJD Barycentric Julian Date
11- 20 E10.5 0.1nm HK ?=- Ca H&K equivalent width
22- 30 E9.4 0.1nm e_HK ?=- Standard error of Ca H&K equivalent width
32- 41 E10.5 0.1nm IRT Ca IRT equivalent width
43- 51 E9.4 0.1nm e_IRT Standard error of Ca IRT equivalent width
53- 62 E10.5 0.1nm Ha Hα equivalent width
64- 72 E9.4 0.1nm e_Ha Standard error of H alpha equivalent width
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Acknowledgements:
Sebastian Kohl, skohl(at)hs.uni-hamburg.de
(End) Patricia Vannier [CDS] 06-Sep-2018