J/AJ/145/45 V light curve of BZ Camelopardalis (Honeycutt+, 2013)
Wind variability in BZ Camelopardalis.
Honeycutt R.K., Kafka S., Robertson J.W.
<Astron. J., 145, 45 (2013)>
=2013AJ....145...45H 2013AJ....145...45H
ADC_Keywords: Binaries, cataclysmic ; Photometry, UBV
Keywords: novae, cataclysmic variables - stars: individual: BZ Cam -
stars: winds, outflows
Abstract:
Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam
were acquired on nine nights in 2005-2006 in order to study the time
development of episodes of wind activity known to occur frequently in
this star. We confirm the results of Ringwald & Naylor that the
P-Cygni absorption components of the lines mostly evolve from higher
expansion velocity to lower velocity as an episode progresses. We also
commonly find blueshifted emission components in the Hα line
profile, whose velocities and durations strongly suggest that they are
also due to the wind. Curiously, Ringwald & Naylor reported common
occurrences of redshifted Hα emission components in their BZ Cam
spectra. We have attributed these emission components in Hα to
occasions when gas concentrations in the bipolar wind (both front side
and back side) become manifested as emission lines as they move beyond
the disk's outer edge. We also suggest, based on changes in the
P-Cygni profiles during an episode, that the progression from larger
to smaller expansion velocities is due to the higher velocity portions
of a wind concentration moving beyond the edge of the continuum light
of the disk first, leaving a net redward shift of the remaining
absorption profile. We derive a new orbital ephemeris for BZ Cam,
using the radial velocity of the core of the HeIλ5876 line,
finding P=0.15353(4). Using this period, the wind episodes in BZ Cam
are found to be concentrated near the inferior conjunction of the
emission line source. This result helps confirm that the winds in
nova-like CVs are often phase dependent, in spite of the puzzling
implication that such winds lack axisymmetry. We argue that the
radiation-driven wind in BZ Cam receives an initial boost by acting on
gas that has been lifted above the disk by the interaction of the
accretion stream with the disk, thereby imposing flickering timescales
onto the wind events, as well as leading to an orbital modulation of
the wind due to the non-axisymmetric nature of the stream/disk
interaction. Simultaneous photometry and spectroscopy were acquired on
three nights in order to test the possible connection between
flickering continuum light and the strength of the front-side wind. We
found strong agreement on one night, some agreement on another, and no
agreement on the third. We suggest that some flickering events lead to
only back-side winds which will not have associated P-Cygni profiles.
Description:
Our long-term BZ Cam photometry consists of three sets, 1990-1996,
2000-2005, and 2007-2012, all using autonomous unattended telescopes
in central Indiana. The first two such sequences (P1, from 1990 May 16
to 1996 Oct 14, and P2, from 2000 Aug 15 to 2005 Feb 21) were obtained
using a 0.41m telescope (informally called RoboScope). Sequence P3 was
acquired from 2007 Sep 1 to 2012 Apr 9 using an 1.25m telescope at the
same site as RoboScope. P3 is missing data between 2009 April 25 and
2010 October 07 because of a detector failure. Sequences P4 (2005 Oct
12), P5 (2006 Feb 21), and P6 (2006 Feb 23) are short-term photometry
having typical spacings of minutes over a single night each. Data for
P4 are from the Tenagra Observatory 0.8m telescope
(http://www.tenagraobservatories.com/) in southern Arizona and the
data for Sequences P5 and P6 are from the 0.91m WIYN telescope at Kitt
Peak.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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06 29 33.96 +71 04 36.3 BZ Camelopardalis = SBC 404 (P=0.15353)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 38 1582 Magnitudes for BZ Cam
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)
B/cb : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2013)
B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2013)
V/123 : Catalog of Cataclysmic Variables (Downes+ 2001-2006)
J/other/NewA/13.133 : 2MASS photometry of cataclysmic variables (Ak+, 2008)
J/other/NewA/12.446 : Absolute magnitudes of cataclysmic variables (Ak+, 2007)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d JD Julian Date of the observation
15- 20 F6.3 mag Vmag [11.992/13.699] Observed V band magnitude
22- 26 F5.3 mag e_Vmag Error in Vmag (1)
28- 38 A11 --- Tel Telescope (IU 50", RoboS, Tenagra, or
WIYN 0.91-m) (2)
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Note (1): Errors are for differential magnitudes with respect to the ensemble
and are mostly ∼0.02mag.
Note (2): Source facility as below:
RoboS = A 0.41m telescope (informally called RoboScope) in central
Indiana.
IU 50" = An unattended, autonomous 1.25m telescope at the same site as
RoboScope.
Tenagra = Tenagra Observatory 0.8m telescope in southern Arizona
(http://www.tenagraobservatories.com/).
WIYN 0.91-m = The 0.91m WIYN (Wisconsin-Indiana-Yale-National optical astronomy
observatory) telescope at Kitt Peak.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 21-Mar-2014