J/AJ/155/12 Photometry of Proxima Centauri observed by BSST (Liu+, 2018)
Searching for the transit of the Earth-mass exoplanet Proxima Centauri b in
Antarctica: preliminary result.
Liu H.-G., Jiang P., Huang X., Yu Z.-Y., Yang M., Jia M., Awiphan S.,
Pan X., Liu B., Zhang H., Wang J., Li Z., Du F., Li X., Lu H., Zhang Z.,
Tian Q.-G., Li B., Ji T., Zhang S., Shi X., Wang J., Zhou J.-L., Zhou H.
<Astron. J., 155, 12 (2018)>
=2018AJ....155...12L 2018AJ....155...12L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Exoplanets ; Photometry, CCD
Keywords: methods: data analysis - planets and satellites: terrestrial planets -
stars: individual (Proxima Centauri) - techniques: photometric
Abstract:
Proxima Centauri is known as the closest star to the Sun. Recently,
radial velocity (RV) observations revealed the existence of an
Earth-mass planet around it. With an orbital period of ∼11 days,
Proxima Centauri b is probably in the habitable zone of its host star.
We undertook a photometric monitoring campaign to search for its
transit, using the Bright Star Survey Telescope at the Zhongshan
Station in Antarctica. A transit-like signal appearing on 2016
September 8 has been tentatively identified. Its midtime,
TC=2457640.1990±0.0017 HJD, is consistent with the predicted
ephemeris based on the RV orbit in a 1σ confidence interval.
Time-correlated noise is pronounced in the light curve of Proxima
Centauri, affecting the detection of transits. We develop a technique,
in a Gaussian process framework, to gauge the statistical significance
of a potential transit detection. The tentative transit signal
reported here has a confidence level of 2.5σ. Further detection
of its periodic signals is necessary to confirm the planetary transit
of Proxima Centauri b. We plan to monitor Proxima Centauri in the next
polar night at Dome A in Antarctica, taking advantage of continuous
darkness. Kipping et al. (2017, J/AJ/153/93) reported two tentative
transit-like signals of Proxima Centauri b observed by the
Microvariability and Oscillation of Stars space telescope in 2014 and
2015. The midtransit time of our detection is 138 minutes later than
that predicted by their transit ephemeris. If all of the signals are
real transits, the misalignment of the epochs plausibly suggests
transit timing variations of Proxima Centauri b induced by an outer
planet in this system.
Description:
We started the photometric monitoring of Proxima Centauri in Antarctica
right after the announcement of the discovery of Proxima Centauri b
(Anglada-Escude et al. 2016Natur.536..437A 2016Natur.536..437A). In August and September,
Proxima Centauri is not observable at almost all observatories around
the world, except for the sites in Antarctica. Our observations were
carried out using the Bright Star Survey Telescope (BSST; Tian et al.
2016, Sci. Bull. 61 383) deployed at the Chinese Antarctic Zhongshan
station (south 69°22'23", east 76°22'17").
BSST (Tian et al. 2016, Sci. Bull. 61 383) is optimally designed for
searching planetary transits of bright stars and will join the ongoing
survey at Kunlun station. It has an aperture size of 300 mm and is
equipped with a large frame 4 Kx4 K CCD camera to receive starlight
from a 3.4°x3.4° field of view (Li et al. 2015, ChOpL 13 11).
We monitored the photometry of Proxima Centauri over 10 nights between
2016 August 29 and September 21. The star was observed in its white light,
without any filter. The typical airmass toward Proxima Centauri was 1.4
all throughout the observation campaign. Five exposures of 3 s are
combined as a photometric point, and a typical cadence of data points
is 220 s.
Objects:
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RA (ICRS) DE Designation(s)
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14 29 42.95 -62 40 46.2 Proxima Centauri b = NAME Proxima b
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 29 626 Photometry of Proxima Centauri Observed by BSST
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See also:
J/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)
J/A+A/603/A58 : Full spectrum of Proxima Centauri (Ribas+, 2017)
J/AJ/153/93 : MOST photometry of Proxima (Kipping+, 2017)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 d HJD [85.1684/108.3503] Heliocentric Julian Date
(HJD-2457545.0) (1)
10- 15 F6.4 --- NFlux [0.9816/1.0177] Normalized differential flux
17- 22 F6.4 --- DFlux [0.9792/1.022] Detrended flux (2)
24- 29 F6.4 --- e_Flux [0.0025/0.0063] Uncertainty in flux
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Note (1): Time has been converted to HJD (Heliocentric Julian Day)
from UTC (Universal Time Coordinated) time.
Note (2): By fitting a cubic polynomial to data observed in individual nights.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 12-Sep-2018