J/A+A/610/L12 KIC 8462852 GTC spectra (Deeg+, 2018)
Non-grey dimming events of KIC 8462852 from GTC spectrophotometry.
Deeg H.J., Alonso R., Nespral D., Boyajian T.
<Astron. Astrophys. 610, L12 (2018)>
=2018A&A...610L..12D 2018A&A...610L..12D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Spectrophotometry ; Spectroscopy
Keywords: stars: individual: KIC 8462852 - stars: peculiar - opacity -
interplanetary medium
Abstract:
We report ground-based spectrophotometry of KIC 8462852, during its
first dimming events since the end of the Kepler mission. The dimmings
show a clear colour-signature, and are deeper in visual blue
wavelengths than in red ones. The flux loss' wavelength dependency can
be described with an absorption Angstroem coefficient of 2.19±0.45,
which is compatible with absorption by optically thin dust with
particle sizes on the order of 0.0015 to 0.15um. These particles would
be smaller than is required to be resistant against blow-out by
radiation pressure when close to the star. During occultation events,
these particles must be replenished on time-scales of days. If dust is
indeed the source of KIC 8462852's dimming events, deeper dimming
events should show more neutral colours, as is expected from optically
thick absorbers.
Description:
Spectra obtained in the follow-up of KIC 8462852 (Boyajian's star)
with OSIRIS at the GTC telescope. These spectra have been reduced as
described in the paper and are contained in two directories, for
target and comparison spectra:
sp_target contains spectra of the target star (KIC 8462852)
sp_compar contains spectra of the comparison star (KIC 8462763)
At each pointing of the GTC, a sequence of 10-45 spectra was
generated. The individual spectra are named:
tpXXYY.dat for the target spectra and
cpXXYY.dat for the comparison spectra,
where XX is the pointing number, and YY is a sequence number.
The format of each spectrum file is a two-column ascii file:
Wavelength (Angstrom) | Flux (arbitrary units))
The files times_pXX.dat correspond to each of the pointings and
contain the times of mid-exposure of each spectrum, in the
HJD_UTC-2400000 framework. These times apply to both target and
comparison spectra and are ordered by increasing sequence number.
There are a total of 516 spectra of the target and 516 spectra of the
comparison.
Objects:
---------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------
20 06 15.5 +44 27 25 KIC 8462852 = Boyajian's Star
20 06 07.7 +44 26 04 KIC 8462763 = TYC 3162-977-1
---------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 97 16 Observed fluxes at each pointing in five
wavelengths bands, indicated by their central
wavelengths in nm
time_p01.dat 51 10 Pointing 01 times of mid-exposure of each spectrum
time_p02.dat 51 45 Pointing 02 times of mid-exposure of each spectrum
time_p03.dat 51 45 Pointing 03 times of mid-exposure of each spectrum
time_p04.dat 51 33 Pointing 04 times of mid-exposure of each spectrum
time_p05.dat 51 30 Pointing 05 times of mid-exposure of each spectrum
time_p06.dat 51 35 Pointing 06 times of mid-exposure of each spectrum
time_p07.dat 51 30 Pointing 07 times of mid-exposure of each spectrum
time_p08.dat 51 31 Pointing 08 times of mid-exposure of each spectrum
time_p09.dat 51 44 Pointing 09 times of mid-exposure of each spectrum
time_p10.dat 51 31 Pointing 10 times of mid-exposure of each spectrum
time_p11.dat 51 19 Pointing 11 times of mid-exposure of each spectrum
time_p12.dat 51 24 Pointing 12 times of mid-exposure of each spectrum
time_p13.dat 51 30 Pointing 13 times of mid-exposure of each spectrum
time_p14.dat 51 35 Pointing 14 times of mid-exposure of each spectrum
time_p15.dat 51 31 Pointing 15 times of mid-exposure of each spectrum
time_p16.dat 51 43 Pointing 16 times of mid-exposure of each spectrum
sp_target/* . 516 Individual target (KIC 8462852) spectra
sp_compar/* . 516 Individual comparison (KIC 8462763) spectra
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Nr [1/16] Pointing sequential number
3 A1 --- n_Nr [ab] Note (1)
5- 14 F10.4 d BJD Observation central time of each pointing
(BJD-2400000)
16- 21 F6.4 --- F556 Observed normalized flux in 556um band
23- 28 F6.4 --- e_F556 rms uncertainty on F556
30- 35 F6.4 --- F618 Observed normalized flux in 618um band
37- 42 F6.4 --- e_F618 rms uncertainty on F618
44- 49 F6.4 --- F709 Observed normalized flux in 709um band
51- 56 F6.4 --- e_F709 rms uncertainty on F709
58- 63 F6.4 --- F792 Observed normalized flux in 792um band
65- 70 F6.4 --- e_F792 rms uncertainty on F792
72- 77 F6.4 --- F868 Observed normalized flux in 868um band
79- 84 F6.4 --- e_F868 rms uncertainty on F868
86- 97 A12 --- FileName Name of the table with times of mid-exposure
of each spectrum for this pointing
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Note (1): Notes as follows:
a = Data not used in analysis due to large scatter from varying exposure times
b = Data not used due to poor sky transparency
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Byte-by-byte Description of file: time_p*.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
4- 25 F22.16 d BJD Time (BJD-2400000)
27- 38 A12 --- spTarget Name of the target spectrum name in
subdirectory sp_target
40- 51 A12 --- spComp Name of the comparison spectrum name in
subdirectory sp_compar
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Byte-by-byte Description of file: sp_compar/* sp_target/*
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 15 F13.7 nm lambda Wavelength
17- 30 F14.7 --- Flux Flux in arbitrary unit
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Acknowledgements:
Roi Alonso, ras(at)iac.es
(End) Patricia Vannier [CDS] 16-Jan-2018