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Title: No Conclusive Evidence for Transits of Proxima b in MOST Photometry

Abstract

The analysis of Proxima Centauri’s radial velocities recently led Anglada-Escudé et al. to claim the presence of a low-mass planet orbiting the Sun’s nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%–40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1 σ –2 σ ), leading us to argue that themore » signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star.« less

Authors:
; ;  [1];  [2]; ; ; ;  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10]; ;  [11];
  1. Department of Astronomy, Columbia University, 550 W. 120th Street, New York, NY 10027 (United States)
  2. Department of Mathematics, Physics and Geology, Cape Breton University, 1250 Grand Lake Road, Sydney, NS B1P 6L2 (Canada)
  3. Department of Astrophysical Sciences, 4 Ivy Lane, Princeton, NJ 08544 (United States)
  4. Department of Physics and Astronomy, Western Washington University, 516 High Street, Bellingham, WA 98225 (United States)
  5. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)
  6. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  7. Observatoire Astronomque du Mont Mégantic, Départment de Physique, Université de Montréal C. P. 6128, Succursale, Centre-Ville, Montréal, QC H3C 3J7 (Canada)
  8. Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States)
  9. Instituto de Astrofísica, Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile)
  10. Observatoire Astronomique de Universite de Genéve, 51 ch. des Maillettes, 1290 Versoix (Switzerland)
  11. Max Plank Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22663966
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; COMPARATIVE EVALUATIONS; MAIN SEQUENCE STARS; MASS; MICROWAVE RADIATION; OSCILLATIONS; PHOTOMETRY; PLANETS; RADIAL VELOCITY; SIGNALS; SPACE; TELESCOPES

Citation Formats

Kipping, David M., Chen, Jingjing, Sandford, Emily, Cameron, Chris, Hartman, Joel D., Bakos, Gáspár Á., Penev, Kaloyan, Csubry, Zoltan, Davenport, James R. A., Matthews, Jaymie M., Sasselov, Dimitar, Rowe, Jason, Siverd, Robert J., Jordán, Andrés, Bayliss, Daniel, Henning, Thomas, Mancini, Luigi, and and others. No Conclusive Evidence for Transits of Proxima b in MOST Photometry. United States: N. p., 2017. Web. doi:10.3847/1538-3881/153/3/93.
Kipping, David M., Chen, Jingjing, Sandford, Emily, Cameron, Chris, Hartman, Joel D., Bakos, Gáspár Á., Penev, Kaloyan, Csubry, Zoltan, Davenport, James R. A., Matthews, Jaymie M., Sasselov, Dimitar, Rowe, Jason, Siverd, Robert J., Jordán, Andrés, Bayliss, Daniel, Henning, Thomas, Mancini, Luigi, & and others. No Conclusive Evidence for Transits of Proxima b in MOST Photometry. United States. doi:10.3847/1538-3881/153/3/93.
Kipping, David M., Chen, Jingjing, Sandford, Emily, Cameron, Chris, Hartman, Joel D., Bakos, Gáspár Á., Penev, Kaloyan, Csubry, Zoltan, Davenport, James R. A., Matthews, Jaymie M., Sasselov, Dimitar, Rowe, Jason, Siverd, Robert J., Jordán, Andrés, Bayliss, Daniel, Henning, Thomas, Mancini, Luigi, and and others. Wed . "No Conclusive Evidence for Transits of Proxima b in MOST Photometry". United States. doi:10.3847/1538-3881/153/3/93.
@article{osti_22663966,
title = {No Conclusive Evidence for Transits of Proxima b in MOST Photometry},
author = {Kipping, David M. and Chen, Jingjing and Sandford, Emily and Cameron, Chris and Hartman, Joel D. and Bakos, Gáspár Á. and Penev, Kaloyan and Csubry, Zoltan and Davenport, James R. A. and Matthews, Jaymie M. and Sasselov, Dimitar and Rowe, Jason and Siverd, Robert J. and Jordán, Andrés and Bayliss, Daniel and Henning, Thomas and Mancini, Luigi and and others},
abstractNote = {The analysis of Proxima Centauri’s radial velocities recently led Anglada-Escudé et al. to claim the presence of a low-mass planet orbiting the Sun’s nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%–40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1 σ –2 σ ), leading us to argue that the signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star.},
doi = {10.3847/1538-3881/153/3/93},
journal = {Astronomical Journal (Online)},
number = 3,
volume = 153,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}