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Mik vannak... L. alant.

Angolul nem =C3=A9rt=C5=91knek: 20 =C3=A9vnyi m=C3=A9r=C3=A9s ut=C3=A1n elk=
=C3=A9pzelhet=C5=91, hogy a BK Lyn
n=C3=B3vaszer=C5=B1 v=C3=A1ltoz=C3=B3 101. december 30-=C3=A1n volt n=C3=B3=
vakit=C3=B6r=C3=A9sben...

(Patterson et al. 2013, MNRAS)

Ksl

We summarize the results of a 20-yr campaign to study the light curves of
BK Lyn, a nova-like star strangely located below the 2 to 3 h
orbital-period gap in the family of cataclysmic variables (CVs). Two
apparent superhumps dominate the nightly light curves, with periods 4.6 per
cent longer, and 3.0 per cent shorter, than the orbital period. The first
appears to be associated with the star=E2=80=99s brighter states (V =E2=88=
=BC 14), while
the second appears to be present throughout and becomes very dominant in
the low state (V =E2=88=BC 15.7). It is plausible that these arise, respect=
ively,
from a prograde apsidal precession and a retrograde nodal precession of the
star=E2=80=99s accretion disc. Starting in the year 2005, the star=E2=80=99=
s light curve
became indistinguishable from that of a dwarf nova =E2=80=93 in particular,=
that of
the ER UMa subclass. No such clear transition has ever been observed in a
CV before. Reviewing all the star=E2=80=99s oddities, we speculate: (a) BK =
Lyn is
the remnant of the probable nova on 101 December 30, and (b) it has been
fading ever since, but it has taken =E2=88=BC2000 yr for the accretion rate=
to drop
sufficiently to permit dwarf-nova eruptions. --


L=C3=A1szl=C3=B3 L. Kiss

Research Professor & Lend=C3=BClet project leader
Konkoly Observatory
Hungarian Academy of Sciences
klaci72@skype
Web: http://www.konkoly.hu/staff/kiss

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