Browsing by Author "Pollacco, D."

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    The EBLM project - VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves
    (2021) Swayne, M., I; Maxted, P. F. L.; Triaud, A. H. M. J.; Sousa, S. G.; Broeg, C.; Floren, H-G; Guterman, P.; Simon, A. E.; Boisse, I; Bonfanti, A.; Martin, D.; Santerne, A.; Salmon, S.; Standing, M. R.; Van Grootel, V.; Wilson, T. G.; Alibert, Y.; Alonso, R.; Anglada Escude, G.; Asquier, J.; Barczy, T.; Barrado, D.; Barros, S. C. C.; Battley, M.; Baumjohann, W.; Beck, M.; Beck, T.; Bekkelien, A.; Benz, W.; Billot, N.; Bonfils, X.; Brandeker, A.; Busch, M-D; Cabrera, J.; Charnoz, S.; Cameron, A. Collier; Csizmadia, Sz; Davies, M. B.; Deleuil, M.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B-O; Dransfield, G.; Ehrenreich, D.; Erikson, A.; Fortier, A.; Fossati, L.; Fridlund, M.; Futyan, D.; Gandolfi, D.; Gillon, M.; Guedel, M.; Hebrard, G.; Heidari, N.; Hellier, C.; Heng, K.; Hobson, M.; Hoyer, S.; Isaak, K. G.; Kiss, L.; Hodzic, V. Kunovac; Lalitha, S.; Laskar, J.; des Etangs, A. Lecavelier; Lendl, M.; Lovis, C.; Magrin, D.; Marafatto, L.; McCormac, J.; Miller, N.; Nascimbeni, V; Olofsson, G.; Ottensamer, R.; Pagano, I; Palle, E.; Peter, G.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I; Santos, N. C.; Scandariato, G.; Segransan, D.; Smith, A. M. S.; Steinberger, M.; Steller, M.; Szabo, Gy M.; Thomas, N.; Udry, S.; Walter, I; Walton, N. A.; Willett, E.
    The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the pycheops data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite - we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have similar to 24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.
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    TOI-222: a single-transit TESS candidate revealed to be a 34-d eclipsing binary with CORALIE, EulerCam, and NGTS
    (2019) Lendl, M.; Bouchy, F.; Gill, S.; Nielsen, L. D.; Turner, O.; Stassun, K.; Acton, J. S.; Anderson, D. R.; Armstrong, D. J.; Bayliss, D.; Belardi, C.; Bryant, E. M.; Burleigh, M. R.; Chaushev, A.; Casewell, S. L.; Cooke, B. F.; Eigmüller, P.; Gillen, E.; Goad, M. R.; Gunther, M. N.; Hagelberg, J.; Jenkins, J. S.; Louden, T.; Marmier, M.; McCormac, J.; Moyano, M.; Pollacco, D.; Raynard, L.; Tilbrook, R. H.; Udry, S.; Vines, J. I.; West, R. G.; Wheatley, P. J.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J.; Jenkins, J. M.; Addison, B.; Briceño, C.; Brahm, R.; Caldwell, D. A.; Doty, J.; Espinoza, N.; Goeke, B.; Henning, T.; Jordán, A.; Krishnamurthy, A.; Law, N.; Morris, R.; Okumura, J.; Mann, A. W.; Rodriguez, J. E.; Sarkis, P.; Schlieder, J.; Twicken, J. D.; Villanueva, S.; Wittenmyer, R. A.; Wright, D. J.; Ziegle, C.
    We report the period, eccentricity, and mass determination for the Transiting Exoplanet Survey Satellite (TESS) single-transit event candidate TOI-222, which displayed a single 3000 ppm transit in the TESS 2-min cadence data from Sector 2. We determine the orbital period via radial velocity measurements (P = 33.9 d), which allowed for ground-based photometric detection of two subsequent transits. Our data show that the companion to TOI-222 is a low-mass star, with a radius of $0.18_{-0.10}^{+0.39}$ R⊙ and a mass of 0.23 ± 0.01 M⊙. This discovery showcases the ability to efficiently discover long-period systems from TESS single-transit events using a combination of radial velocity monitoring coupled with high-precision ground-based photometry.
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    Two Transiting Hot Jupiters from the WASP Survey : WASP-150b and WASP-176b
    (2020) Cooke, B. F.; Pollacco, D.; Almleaky, Y.; Barkaoui, K.; Benkhaldoun, Z.; Blake, J. A.; Bouchy, F.; Boumis, P.; Brown, D. J. A.; D’Ago, Giuseppe; Bruni, I.; Burdanov, A.; Cameron, A. C.; Chote, P.; Daassou, A.; Dalal, S.; Damasso, M.; Delrez, L.; Doyle, A. P.; Ducrot, E.; Gillon, M.; Hebrard, G.; Hellier, C.; Henning, T.; Jehin, E.; Kiefer, F.; King, G. W.; Liakos, A.; Lopez, T.; Mancini, L.; Mardling, R.; Maxted, P. F. L.; McCormac, J.; Murray, C.; Nielsen, L. D.; Osborn, H.; Palle, E.; Pepe, F.; Pozuelos, F. J.; Prieto-Arranz, J.; Queloz, D.; Schanche, N.; Segransan, D.; Smalley, B.; Southworth, J.; Thompson, S.; Turner, O.; Udry, S.; Velasco, S.; West, R.; Wheatley, P