J/A+A/625/A34 Photometry of CU Vir (Krticka+, 2019)
HST/STIS analysis of the first main sequence pulsar CU Virginis.
Krticka J., Mikulasek Z., Henry G. W., Janik J., Kochukhov O., Pigulski A.,
Leto P., Trigilio C., Krtickova I., Lueftinger T., Prvak M., Tichy A.
<Astron. Astrophys. 625, A34 (2019)>
=2019A&A...625A..34K 2019A&A...625A..34K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Ap ; Photometry, UBV
Keywords: stars: chemically peculiar - stars: early type -
stars: variables: general - stars: individual CU Vir
Abstract:
CU Vir has been the first main sequence star that showed regular radio
pulses that persist for decades, resembling the radio lighthouse of
pulsars and interpreted as auroral radio emission similar to that
found in planets. The star belongs to a rare group of magnetic
chemically peculiar stars with variable rotational period. We study
the ultraviolet (UV) spectrum of CU Vir obtained using STIS
spectrograph onboard the Hubble Space Telescope (HST) to search for
the source of radio emission and to test the model of the rotational
period evolution. We used our own far-UV and visual photometric
observations supplemented with the archival data to improve the
parameters of the quasisinusoidal long-term variations of the
rotational period. We predict the flux variations of CU Vir from
surface abundance maps and compare these variations with UV flux
distribution. We searched for wind, auroral, and interstellar lines in
the spectra. The UV and visual light curves display the same long-term
period variations supporting their common origin. New updated
abundance maps provide better agreement with the observed flux
distribution. The upper limit of the wind mass-loss rate is about
10-12M☉/yr. We do not find any auroral lines. We find
rotationally modulated variability of interstellar lines, which is
most likely of instrumental origin. Our analysis supports the flux
redistribution from far-UV to near-UV and visual domains originating
in surface abundance spots as the main cause of the flux variability
in chemically peculiar stars. Therefore, UV and optical variations are
related and the structures leading to these variations are rigidly
confined to the stellar surface. The radio emission of CU Vir is most
likely powered by a very weak presumably purely metallic wind, which
leaves no imprint in spectra.
Description:
Time-resolved photometry of CU Vir derived using APT and SMEI is
presented.
Objects:
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RA (2000) DE Designation(s)
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14 12 15.81 +02 24 34.0 CU Vir = HR 5313
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
apt.dat 21 2054 APT photometry
smei.dat 28 19226 SMEI photometry
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See also:
J/MNRAS/431/2106 : CU Vir Stroemgren differential photometry (Pyper+, 2013)
Byte-by-byte Description of file: apt.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d HJD Heliocentric Julian date of observation
(HJD-2400000)
13- 18 F6.3 mag dmag Magnitue difference with respect to the
comparison star
21 A1 --- Filter [BV] Filter
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Byte-by-byte Description of file: smei.dat
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Bytes Format Units Label Explanations
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4- 12 F9.3 d HJD Heliocentric Julian date of observation
(HJD-2400000)
15- 28 E14.7 mag dmag Magnitue difference with respect to the
comparison star
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Acknowledgements:
Jiri Krticka, krticka(at)physics.muni.cz
(End) Jiri Krticka [MU, Czech Republic], Patricia Vannier [CDS] 28-Apr-2019