J/AJ/156/12 Photometry of β Lyrae by the BRITE satellites (Rucinski+, 2018)
Light-curve instabilities of β Lyrae observed by the BRITE satellites.
Rucinski S.M., Pigulski A., Popowicz A., Kuschnig R., Kozlowski S.,
Moffat A.F.J., Pavlovski K., Handler G., Pablo H., Wade G.A., Weiss W.W.,
Zwintz K.
<Astron. J., 156, 12-12 (2018)>
=2018AJ....156...12R 2018AJ....156...12R (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Photometry ; Optical
Keywords: binaries: close - binaries: eclipsing -
stars: individual: β Lyr - techniques: photometric
Abstract:
Photometric instabilities of β Lyrae (β Lyr) were observed
in 2016 by two red-filter BRITE satellites over more than 10 revolutions
of the binary, with ∼100 minute sampling. Analysis of the time series
shows that flares or fading events take place typically three to five
times per binary orbit. The amplitudes of the disturbances (relative
to the mean light curve, in units of the maximum out-of-eclipse light
flux, f.u.) are characterized by a Gaussian distribution with
σ=0.0130±0.0004 f.u. Most of the disturbances appear to be random,
with a tendency to remain for one or a few orbital revolutions, sometimes
changing from brightening to fading or the reverse. Phases just preceding
the center of the deeper eclipse showed the most scatter while phases
around the secondary eclipse were the quietest. This implies that the
invisible companion is the most likely source of the instabilities.
Wavelet transform analysis showed the domination of the variability scales
at phase intervals 0.05-0.3 (0.65-4 days), with the shorter (longer)
scales dominating in numbers (variability power) in this range. The
series can be well described as a stochastic Gaussian process with the
signal at short timescales showing a slightly stronger correlation
than red noise. The signal decorrelation timescale, τ=(0.068±0.018)
in phase or (0.88±0.23) days, appears to follow the same dependence
on the accretor mass as that observed for active galactic nucleus and
quasi-stellar object masses five to nine orders of magnitude larger than
the β Lyr torus-hidden component.
Description:
The observational material obtained during the 2016 visibility season
of β Lyr consists mainly of photometric observations from two
satellites of the BRITE Constellation equipped with red filters,
"BRITE-Toronto" (BTr) and "Uni-BRITE" (UBr). The BRITE observations
started on 2016 May 4 and ended on 2016 October 3, and thus lasted
152 days. The exposures were taken at 20 s intervals with the duration
of 1 s for the UBr satellite, which is a typical choice for bright stars,
preventing the saturation of the CCD pixels.
Objects:
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RA (ICRS) DE Designation(s)
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18 50 04.80 +33 21 45.6 β Lyrae = * bet Lyr
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 39 2119 The satellite-orbit average data
table3.dat 26 100 The mean light curve of β Lyr
table5.dat 19 1383 The equal-step δ series
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See also:
J/AJ/110/1350 : Beta Lyrae light curve changes (Van Hamme+ 1995)
J/A+A/312/879 : Beta Lyr radial velocities and UBV data (Harmanec+, 1996)
J/A+A/463/233 : UBV and radial velocity light curves of beta Lyr (Ak+, 2007)
J/ApJ/750/59 : BVR polarimetric observations of β Lyr (Lomax+, 2012)
J/A+A/618/A112 : β Lyr light curves (Mourard+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d t [1520.1052/1651.97] Mean time for the
satellite-orbit average data (HJD-2456000)
11- 18 F8.5 --- Phase [0.11435/10.3019] Orbital phase of β Lyr,
Φ (G1)
20- 26 F7.5 --- Flux [0.46531/1.03572] Relative flux (1)
28- 34 F7.5 --- e_Flux [0.00035/0.0058] Error computed from the spread
of measurements (2)
36- 37 I2 --- o_Flux [8/75] Number of flux measurements
39 I1 --- Code [1/3] Satellite/setup code (3)
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Note (1): Flux in units of the assumed maximum value.
Note (2): Error computed from the spread of the contributing o_Flux individual
observations.
Note (3): Satellite/setup code as follows:
1 = UBr;
2 = BTr-3;
3 = BTr-4.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.5 --- Phase [0.00492/0.99511] Mean fractional phase of
β Lyr, Φ (G1)
9- 15 F7.5 --- Fluxmean [0.50429/1.00091] Mean flux calculated per
interval of 0.01 in phase
17- 23 F7.5 --- e_Fluxmean [0.00172/0.00917] Error computed from the
spread of measurements (1)
25- 26 I2 --- o_Fluxmean [12/20] Number of flux measurements
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Note (1): Error computed from the spread of the contributing o_Fluxmean
individual satellite-orbit points.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 8 F8.5 --- d1 [-0.04874/0.04311] Flux deviation for un-corrected
series δ1 (1)
10- 17 F8.5 --- d2 [-0.05012/0.03332] Flux deviation for
trend-corrected series δ2 (1)
19 I1 --- Code [0/2]? Measurement code (2)
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Note (1): We carried out the analysis for both the uncorrected (mean-subtracted)
and the trend-corrected series of deviations and attempted to monitor the
resulting differences. See Section 4.2 for more details.
Note (2): The measurement code signifies:
0 = Missing point, interpolated using entries with codes 1 and 2;
1 = Observed, BTr-4 setup;
2 = Observed by UBr, interpolated into the equal-step BTr-4 series.
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Global notes:
Note (G1): The orbital phase of β Lyr is computed from
Φ=(t-1518.6251)/12.943296. See also Section 2.4. The phase includes the
number of binary orbital cycles from the zero epoch.
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History:
From electronic version of the journal
References:
Rucinski et al. Paper II. 2019AJ....158..148R 2019AJ....158..148R
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 10-Jan-2019