J/A+A/638/A120 SPHERE maps around Proxima Cen (Gratton+, 2020)
Searching for the near-infrared counterpart of Proxima c using multi-epoch
high-contrast SPHERE data at VLT.
Gratton R., Zurlo A., Le Coroller H., Damasso M., Del Sordo F., Langlois M.,
Mesa D., Milli J., Chauvin G., Desidera S., Hagelberg J., Lagadec E.,
Vigan A., Boccaletti A., Bonnefoy M., Brandner W., Brown S., Cantalloube F.,
Delorme P., D'Orazi V., Feldt M., Galicher R., Henning T., Janson M.,
Kervella P., Lagrange A-M., Lazzoni C., Ligi R., Maire A-L., Menard F.,
Meyer M., Mugnier L., Potier A., Rickman E.L., Rodet L., Romero C.,
Schmidt T., Sissa E., Sozzetti A., Szulagyi J., Wahhaj Z., Antichi J.,
Fusco T., Stadler E., Suarez M., Wildi F.
<Astron. Astrophys. 638, A120 (2020)>
=2020A&A...638A.120G 2020A&A...638A.120G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets
Keywords: planets and satellites: detection -
planets and satellites: individual: Proxima c -
star: individual: Proxima -
planets and satellites: terrestrial planets -
instrumentation: high angular resolution -
techniques: image processing
Abstract:
Proxima Centauri is the closest star to the Sun and it is known
to host an Earth-like planet in its habitable zone; very recently a
second candidate planet was proposed based on radial velocities. At
quadrature, the expected projected separation of this new candidate is
larger than 1 arcsec, making it a potentially interesting target for
direct imaging.
While identification of the optical counterpart of this planet is
expected to be very difficult, successful identification would allow
for a detailed characterization of the closest planetary system.
We searched for a counterpart in SPHERE images acquired over four
years through the SHINE survey. In order to account for the expected
large orbital motion of the planet, we used a method that assumes the
circular orbit obtained from radial velocities and exploits the
sequence of observations acquired close to quadrature in the orbit. We
checked this with a more general approach that considers Keplerian
motion, called K-stacker.
We did not obtain a clear detection. The best candidate has S/N=6.1 in
the combined image. A statistical test suggests that the probability
that this detection is due to random fluctuation of noise is <1%, but
this result depends on the assumption that the distribution of noise
is uniform over the image, a fact that is likely not true. The
position of this candidate and the orientation of its orbital plane
fit well with observations in the ALMA 12m array image. However, the
astrometric signal expected from the orbit of the candidate we
detected is 3-sigma away from the astrometric motion of Proxima as
measured from early Gaia data. This, together with the unexpectedly
high flux associated with our direct imaging detection, means we
cannot confirm that our candidate is indeed Proxima c.
On the other hand, if confirmed, this would be the first observation
in imaging of a planet discovered from radial velocities and the
second planet (after Fomalhaut b) of reflecting circumplanetary
material. Further confirmation observations should be done as soon as
possible.
Description:
SPHERE IRDIS SNR maps, H2 and H3 filters for individual epochs of the
SPHERE GTO observations of Proxima
Objects:
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RA (2000) DE Designation(s)
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14 29 42.95 -62 40 46.2 Proxima = V* V645 Cen
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 116 13 List of fits maps
fits/* . 13 Individual fits maps
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See also:
J/A+A/534/A133 : Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)
J/AJ/153/93 : MOST photometry of Proxima (Kipping+, 2017)
J/A+A/603/A58 : Full spectrum of Proxima Centauri (Ribas+, 2017)
J/AJ/155/12 : Photometry of Proxima Centauri observed by BSST (Liu+, 2018)
J/A+A/626/A111 : Proxima Cen flare activity temporal changes (Pavlenko+, 2019)
J/AJ/157/226 : Photometry of Proxima Centauri from 2006 to 2017 (Feliz+ 2019)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 53 A24 "datime" Obs.date Observation date
55- 58 I4 Kibyte size Size of FITS file
60- 72 A13 --- FileName Name of FITS file, in subdirectory fits
74-116 A43 --- Title Title of the FITS file
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Acknowledgements:
Raffaele Gratton, raffaele.gratton(at)inaf.it
(End) Patricia Vannier [CDS] 23-Apr-2020