J/A+A/654/A159 CHEOPS photometry of Au Mic b transits in 2020 (Szabo+, 2021)
The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and
transit timing variations as seen by CHEOPS and TESS.
Szabo Gy.M., Gandolfi D., Brandeker A., Csizmadia S., Garai Z., Billot N.,
Broeg C., Ehrenreich D., Fortier A., Fossati L., Hoyer S., Kiss L.,
Lecavelier des Etangs A.., Maxted P.F.L., Ribas I., Alibert Y., Alonso R.,
Anglada Escude G., Barczy T., Barros S.C.C., Barrado D., Baumjohann W.,
Beck M., Beck T., Bekkelien A., Bonfils X., Benz W., Borsato L.,
Busch M.-D., Cabrera J., Charnoz S., Collier Cameron A.,
Van Damme C.C., Davies M.B., Delrez L., Deleuil M., Demangeon O.D.S.,
Demory B.-O., Erikson A., Fridlund M., Futyan D., Garcia Munoz A.,
Gillon M., Guedel M., Guterman P., Heng K., Isaak K.G., Lacedelli G.,
Laskar J., Lendl M., Lovis C., Luntzer A., Magrin D., Nascimbeni V.,
Olofsson G., Osborn H.P., Ottensamer R., Pagano I., Palle E., Peter G.,
Piazza D., Piotto G., Pollacco D., Queloz D., Ragazzoni R., Rando N.,
Rauer H., Santos N.C., Scandariato G., Segransan D., Serrano L.M.,
Sicilia D., Simon A.E., Smith A.M.S., Sousa S.G., Steller M., Thomas N.,
Udry S., Van Grootel V., Walton N.A., Wilson T.G.
<Astron. Astrophys., 654, A159 (2021)>
=2021A&A...654A.159S 2021A&A...654A.159S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical
Keywords: planetary systems: individual: AU Mic
Abstract:
AU Mic is a young planetary system with a resolved debris disc showing
signs of planet formation and two transiting warm Neptunes near
mean-motion resonances. Here we analyse three transits of AU Mic b
observed with the CHaracterising ExOPlanet Satellite (CHEOPS),
supplemented with sector 1 and 27 Transiting Exoplanet Survey
Satellite (TESS) photometry, and the All-Sky Automated Survey from the
ground. The refined orbital period of AU Mic b is
8.462995±0.000003d, whereas the stellar rotational period is
Prot=4.8367±0.0006d. The two periods indicate a 7:4 spin-orbit
commensurability at a precision of 0.1%. Therefore, all transits are
observed in front of one of the four possible stellar central
longitudes. This is strongly supported by the observation that the
same complex star-spot pattern is seen in the second and third CHEOPS
visits that were separated by four orbits (and seven stellar
rotations). Using a bootstrap analysis we find that flares and star
spots reduce the accuracy of transit parameters by up to 10% in the
planet-to-star radius ratio and the accuracy on transit time by
3-4 min. Nevertheless, occulted stellar spot features independently
confirm the presence of transit timing variations (TTVs) with an
amplitude of at least 4 min. We find that the outer companion,
AU Mic c, may cause the observed TTVs.
Description:
Processed CHEOPS PIPE photometry of the transits in the form as it is
shown in Fig. 2. of the paper. The processing consisted of trend
filtering and normalisation for out-of-transit flux.
Objects:
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RA (2000) DE Designation(s)
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20 45 09.53 -31 20 27.2 Au Mic = TOI-2221
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
aumic_b.dat 23 8435 CHEOPS photometry of Au Mic b transits in 2020
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See also:
J/AJ/162/137 : Minerva-Australis radial velocity of AU Mic (Addison+, 2021)
J/A+A/659/L7 : AU Mic b and c transits with CHEOPS (Szabo+, 2022)
J/AJ/164/110 : HST/COS far-UV spectra of AU Mic flares (Feinstein+, 2022)
Byte-by-byte Description of file: aumic_b.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD CHEOPS barycentric Julian date
16- 23 F8.6 --- Flux Relative flux
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Acknowledgements:
Gyula M. Szabo, szgy(at)gothard.hu
(End) Gyula M. Szabo [ELTE GAO, Hungary], Patricia Vannier [CDS] 15-May-2023