TY - JOUR
T1 - A high-contrast search for variability in HR 8799bc with VLT-SPHERE
AU - Biller, Beth A.
AU - Apai, Dániel
AU - Bonnefoy, Mickaël
AU - Desidera, Silvano
AU - Gratton, Raffaele
AU - Kasper, Markus
AU - Kenworthy, Matthew
AU - Lagrange, Anne Marie
AU - Lazzoni, Cecilia
AU - Mesa, Dino
AU - Vigan, Arthur
AU - Wagner, Kevin
AU - Vos, Johanna M.
AU - Zurlo, Alice
N1 - Publisher Copyright: © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2021/5/1
Y1 - 2021/5/1
N2 - The planets HR8799bc display nearly identical colours and spectra as variable young exoplanet analogs such as VHS 1256-1257ABb and PSO J318.5-22, and are likely to be similarly variable. Here we present results from a 5-epoch SPHERE IRDIS broadband-H search for variability in these two planets. HR 8799b aperture photometry and HR 8799bc negative simulated planet photometry share similar trends within uncertainties. Satellite spot lightcurves share the same trends as the planet lightcurves in the August 2018 epochs, but diverge in the October 2017 epochs. We consider Δ(mag)b-Δ(mag)c to trace non-shared variations between the two planets, and rule out non-shared variability in Δ(mag)b-Δ(mag)c to the 10-20 rm per\cent level over 4-5 h. To quantify our sensitivity to variability, we simulate variable lightcurves by inserting and retrieving a suite of simulated planets at similar radii from the star as HR 8799bc, but offset in position angle. For HR 8799b, for periods <10 h, we are sensitive to variability with amplitude > 5 per\cent. For HR 8799c, our sensitivity is limited to variability > 25 per\cent for similar periods.
AB - The planets HR8799bc display nearly identical colours and spectra as variable young exoplanet analogs such as VHS 1256-1257ABb and PSO J318.5-22, and are likely to be similarly variable. Here we present results from a 5-epoch SPHERE IRDIS broadband-H search for variability in these two planets. HR 8799b aperture photometry and HR 8799bc negative simulated planet photometry share similar trends within uncertainties. Satellite spot lightcurves share the same trends as the planet lightcurves in the August 2018 epochs, but diverge in the October 2017 epochs. We consider Δ(mag)b-Δ(mag)c to trace non-shared variations between the two planets, and rule out non-shared variability in Δ(mag)b-Δ(mag)c to the 10-20 rm per\cent level over 4-5 h. To quantify our sensitivity to variability, we simulate variable lightcurves by inserting and retrieving a suite of simulated planets at similar radii from the star as HR 8799bc, but offset in position angle. For HR 8799b, for periods <10 h, we are sensitive to variability with amplitude > 5 per\cent. For HR 8799c, our sensitivity is limited to variability > 25 per\cent for similar periods.
KW - (stars:) brown dwarfs
KW - infrared: planetary systems
KW - planets and satellites: gaseous planets
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U2 - 10.1093/mnras/stab202
DO - 10.1093/mnras/stab202
M3 - Article
SN - 0035-8711
VL - 503
SP - 743
EP - 767
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -