Volume 628, August 2019
|Number of page(s)||8|
|Section||Planets and planetary systems|
|Published online||14 August 2019|
Indications for transit-timing variations in the exo-Neptune HAT-P-26b★
Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University,
Ny Munkegade 120,
8000 Aarhus C, Denmark
2 Astronomical Observatory, Institute of Theoretical Physics and Astronomy, Vilnius University, Sauletekio av. 3, 10257 Vilnius, Lithuania
3 Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029 Blindern, 0315 Oslo, Norway
4 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque, B1900FWA, La Plata, Argentina
5 Instituto de Astrofísica de La Plata (CCT-La Plata, CONICET-UNLP), Paseo del Bosque, B1900FWA La Plata, Argentina
6 Complejo Astronómico El Leoncito (CONICET-UNLP-UNC-UNSJ), Av. España 1512 Sur, San Juan, Argentina
7 Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
8 Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Victoria 3800, Australia
9 Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
Accepted: 15 April 2019
Upon its discovery, the low-density transiting Neptune HAT-P-26b showed a 2.1σ detection drift in its spectroscopic data, while photometric data showed a weak curvature in the timing residuals, the confirmation of which required further follow-up observations. To investigate this suspected variability, we observed 11 primary transits of HAT-P-26b between March, 2015, and July, 2018. For this, we used the 2.15 m Jorge Sahade Telescope placed in San Juan, Argentina, and the 1.2 m STELLA and the 2.5 m Nordic Optical Telescope, both located in the Canary Islands, Spain. To add to valuable information on the transmission spectrum of HAT-P-26b, we focused our observations in the R-band only. To contrast the observed timing variability with possible stellar activity, we carried out a photometric follow-up of the host star over three years. We carried out a global fit to the data and determined the individual mid-transit times focusing specifically on the light curves that showed complete transit coverage. Using bibliographic data corresponding to both ground and space-based facilities, plus our new characterized mid-transit times derived from parts-per-thousand precise photometry, we observed indications of transit timing variations in the system, with an amplitude of ~4 min and a periodicity of ~270 epochs. The photometric and spectroscopic follow-up observations of this system will be continued in order to rule out any aliasing effects caused by poor sampling and the long-term periodicity.
Key words: instrumentation: photometers / techniques: photometric / time / planets and satellites: fundamental parameters / stars: activity
The transit photometry (time, flux, error) and the long term monitoring in three bands are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A116
© ESO 2019
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