J/A+A/584/A17 phi Dra BVRI light curves (Prvak+, 2015)
Modelling of variability of the CP star phi Draconis.
Prvak M., Liska J., Krticka J., Mikulasek Z., Luftinger T.
<Astron. Astrophys. 584, A17 (2015)>
=2015A&A...584A..17P 2015A&A...584A..17P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, CCD ; Photometry, UBVRI
Keywords: stars: chemically peculiar - stars: early type - stars: variables -
stars: individual: phi Dra
Abstract:
The presence of heavier chemical elements in stellar atmospheres
influences the spectral energy distribution of stars. An uneven
surface distribution of these elements, together with flux
redistribution and stellar rotation, are commonly believed to be the
primary causes of the variability of chemically peculiar (CP) stars.
We aim to model the photometric variability of the CP star phi Dra
based on the assumption of inhomogeneous surface distribution of
heavier elements and compare it to the observed variability of the
star. We also intend to identify the processes that contribute most
significantly to its photometric variability.
We use a grid of TLUSTY model atmospheres and the SYNSPEC code to
model the radiative flux emerging from the individual surface elements
of phi Dra with different chemical compositions. We integrate the
emerging flux over the visible surface of the star at different phases
throughout the entire rotational period to synthesise theoretical
light curves of the star in several spectral bands.
Description:
Differential ensemble photometry for bright CP star phi Draconis.
Measurements were obtained using a small refractor. The observations
were performed at the Masaryk University Observatory (2 nights) and at
the Brno Observatory and Planetarium (15 nights) in the Czech Republic
from May to July 2013. Only the 12 best nights were selected.
Observing equipment consisted of a photographic lens Jupiter 3.5/135mm
(lens speed/focal length) and a Moravian Instruments CCD camera
G2-0402 with Johnson-Cousins photometric filters BVRI. The angular
resolution was only 14"/pixel and thus it was not enough for angular
separation of the fainter visual B component (actual distance around
0.5"). CCD images were calibrated in a standard way (dark frame and
flat field corrections). The C-Munipack software (Motl 2009) was used
for this processing as well as for differential ensemble photometry.
Stars HD 169666 and HD 171044 were used as comparison stars.
Objects:
----------------------------------------------------------------
RA (2000) DE Designation(s) Per
----------------------------------------------------------------
18 20 45.43 +71 20 16.1 phi Dra = HD 170000 1.716500(2)d
----------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 28 4250 BVRI-photometry of phi Dra
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d HJD Heliocentric Julian Date
15- 20 F6.3 mag mag Magnitude in Band
22- 26 F5.3 mag e_mag Uncertainty of magnitude
28 A1 --- Band [BVRI] Photometric band, Johnson-Cousins bands
--------------------------------------------------------------------------------
Acknowledgements:
Milan Prvak, prvak(at)physics.muni.cz
DTPA, Masaryk University, Czech Republic
(End) Milan Prvak [DTPA, Czech Republic], Patricia Vannier [CDS] 10-Sep-2015