2021A&A...654A.159S

Query : 2021A&A...654A.159S

2021A&A...654A.159S - Astronomy and Astrophysics, volume 654A159-159 (2021/10-1)

The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS.

SZABO G.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., CORRAL VAN DAMME 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. and WILSON T.G.

Abstract (from CDS):

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±0.000003 d, whereas the stellar rotational period is Prot = 4.8367±0.0006 d. 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.

Abstract Copyright: © ESO 2021

Journal keyword(s):

VizieR on-line data: <Available at CDS (J/A+A/654/A159): aumic_b.dat>

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 * bet Pic PM* 05 47 17.0876901 -51 03 59.441135 4.13 4.03 3.86 3.74 3.58 A6V 2087 1
2 WASP-19 * 09 53 40.0765648584 -45 39 33.057187596   13.05 12.31 12.12 11.35 G8V 207 2
3 BD+07 2474 ** 11 43 38.016288 +06 33 49.41900   11.15 10.41 10.34   G5 41 0
4 WASP-107b Pl 12 33 32.8441110816 -10 08 46.225572324           ~ 289 0
5 Qatar 2 PM* 13 50 37.4100326640 -06 48 14.421574044   14.0   13.45   K5V 72 1
6 BD+46 2629 ** 19 07 53.104944 +46 52 06.00420   10.12 9.70 9.80   kA2hA5mA7(IV)m: 173 0
7 CoRoT-2 * 19 27 06.4944378024 +01 23 01.359897468   13.422 12.568 12.204 11.49 G7V+K9V 267 2
8 CoRoT-2b Pl 19 27 06.4944378024 +01 23 01.359897468           ~ 256 1
9 BD+47 2936 EB* 19 50 50.2472976936 +48 04 51.101390496       8.8   K4V 359 1
10 BD+47 2936b Pl 19 50 50.2472976936 +48 04 51.101390496           ~ 493 1
11 Kepler-17 Ro* 19 53 34.8643397568 +47 48 54.049530564   14.6   13.6   G5V 175 1
12 HD 197481b Pl 20 45 09.5324974119 -31 20 27.237889841           ~ 158 0
13 HD 197481 BY* 20 45 09.5324974119 -31 20 27.237889841   10.05 8.627 9.078 6.593 M1VeBa1 1344 0
14 HD 197481c Pl 20 45 09.5324974119 -31 20 27.237889841           ~ 82 0
15 WASP-4 PM* 23 34 15.0857248317 -42 03 41.047972591   13.51 12.48 11.9   G7V 196 1

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