J/A+A/613/L5 Hα emitting sources around MWC758 (Huelamo+, 2018)
Searching for Hα emitting sources around MWC758:
SPHERE/ZIMPOL high-contrast imaging.
Huelamo N., Chauvin G., Schmid H.M., Quanz S.P., Whelan E., Lillo-Box J.,
Barrado D., Montesinos B., Alcala J.M., Benisty M., de Gregorio-Monsalvo I.,
Mendigutia I., Bouy H., Merin B., de Boer J., Garufi A., Pantin E.
<Astron. Astrophys. 613, L5 (2018)>
=2018A&A...613L...5H 2018A&A...613L...5H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Stars, pre-main sequence ; Photometry, infrared
Keywords: stars: pre-main sequence - stars: planetary systems -
stars: individual: MWC758 - accretion, accretion disks -
techniques: high angular resolution
Abstract:
MWC758 is a young star surrounded by a transitional disk. The disk
shows an inner cavity and spiral arms that could be caused by the
presence of protoplanets. Recently, a protoplanet candidate has been
detected around MWC758 through high-resolution L'-band observations.
The candidate is located inside the disk cavity at a separation of 111
mas from the central star, and at an average position angle of
165.5°.
We aim at detecting accreting protoplanet candidates within the disk
of MWC758 through spectral angular differential imaging observations
in the optical regime. In particular, we explore the emission at the
position of the detected planet candidate.
We have performed simultaneous adaptive optics observations in the
Hα line and the adjacent continuum using SPHERE/ZIMPOL at the
Very Large Telescope (VLT).
The data analysis does not reveal any Hα signal around the
target. The derived contrast curve in the B_Ha filter allows us to
derive a 5σ upper limit of 7.6mag at 111mas, the separation of
the previously detected planet candidate. This contrast translates
into a Hα line luminosity of LHα≲5*10-5L☉ at
111mas. Assuming that LHα scales with Lacc as in Classical T
Tauri stars as a first approximation, we can estimate an accretion
luminosity of Lacc<3.7*10-4L☉ for the protoplanet candidate.
For the predicted mass range of MWC758b, 0.5-5MJup, this implies
accretion rates smaller than dM/dt<3.4*(10-8-10-9)M[sun/yr, for
an average planet radius of 1.1 RJup. Therefore, our estimates are
consistent with the predictions of accreting circumplanetary accretion
models for Rin=1RJup. The ZIMPOL line luminosity is consistent
with the Hα upper limit predicted by these models for truncation
radii ≲3.2RJup.
The non-detection of any Hαemitting source in the ZIMPOL images
does not allow us to unveil the nature of the L' detected source.
Either it is a protoplanet candidate or a disk asymmetry.
Description:
The SPHERE Open Time observations (096.C-0267.A) were obtained on
December 30, 2015. The ZIMPOL instrument of SPHERE was used in
spectral and angular differential imaging modes. In addition to the
pupil stabilized mode, ZIMPOL simultaneously imaged MWC758 in two
different filters: B_Ha (λc=655.6nm and δλ=5.5nm)
and Cnt_Ha (λc=644.9nm and δλ=4.1nm). We obtained
190 individual exposures of 60 seconds each, resulting in a total
exposure time of 3 hours on-source (from 02:20UT to 05:24 UT).
Objects:
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RA (2000) DE Designation(s)
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05 30 27.53 +25 19 57.1 MWC 758 = HD 36112
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 162 3 List of fits images
fits/* . 3 Individual fits images
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See also:
J/A+A/578/L6 : Polarized images of MWC758 (Benisty+, 2015)
J/A+A/611/A74 : Angular differential imaging of MCW 758 (Reggiani+, 2018)
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- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 30 I3 Kibyte size Size of FITS file
32- 72 A41 --- FileName Name of FITS file, in subdirectory fits
74-162 A89 --- Title Title of the FITS file
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Acknowledgements:
Nuria Huelamo, nhuelamo(at)cab.inta-csic.es
(End) Patricia Vannier [CDS] 04-Jun-2018