IPs
AE Aqr
FO Aqr
XY Ari
V405 Aur
HT Cam
MU Cam
DW Cnc
BG CMi
V709 Cas
V1025 Cen
TV Col
TX Col
UU Col
V2306 Cyg
YY Dra
PQ Gem
DQ Her
EX Hya
NY Lup
V2400 Oph
GK Per
AO Psc
WX Pyx
V1223 Sgr
V1062 Tau
EI UMa
IGR 00234
IGR 15094
IGR 17303
Swift J0732
RX J0704
RX J1803
RX J2133
XSS 00564
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Criteria for IP Classification
On this site, I have the absolute power to decide which systems
I include as IPs, which as candidates. Now I have started a 5-tier
system from "ironclad" to "doubtful."
"Ironclad" is used for systems that so obviously belong
to the class, there are no arguments (e.g.,
AO Psc), while "confirmed"
systems do not have as many independent lines of evidence.
"Probable" and &possible" indicate the lack of
hard evidence either way, but that I have my personal guesses
as to whether they are IPs ("probable") or not
("possible"). "Doubtful" usually means
there are later papers that disagree with the IP classification.
Joe's 1994 review
contains a section titled "The Cast: Rules of the Audition."
Of his 6 criteria, I would not be bothered by a lack of circular
polarization or a relatively soft X-ray spectrum - there are confirmed
IPs with neither. However, I place a stronger emphasis on optical
emission lines. Penning's pioneering
work as well as many papers by Coel Hellier and company show that
IPs have radial velocity (or its proxy, V/R ratio) modulation on the
spin period. This is easy to underatsnd: a significant fraction of
optical emission lines in IPs come from the "accretion curtain."
So, if time-resolved optical spectroscopy with a sufficient
sensitivity fails to show such a behavior, I would take that as
a strong negative.
Of course, the usual criteria for IP classification is optical
and X-ray spin modulations.
When the classification depends on the optical periodicity,
it should be coherent and persistent to a high degree.
It has to be repeatedly observed, ideally over several years;
If you see apparent modulations for a few cycles --- don't get
too excited. I think every CV observer should read
Warner's Warning
before attempting to identify periodicities in CVs. If I were writing
my papers on KO Vel now, with the same data, I would probably write
a very different paper.
When X-ray pulses are involved, I would relax the requirement
--- two independent X-ray pulse period determinations would be sufficient
for me (assuming it is known to be a CV and the periods agree).
It is not sufficient for a sub-orbital X-ray periodicity to be seen once.
Such one-time-only X-ray periodicities have been seen in many
non-magnetic CVs. Usually in such systems, different
periods are seen in different X-ray observations, proving that
these X-ray modulations are not tied directly to the spin period
of the white dwarf.
I would also happily accept somewhat weak optical detection
(in terms of establishing persistence and coherence)
combined with a single X-ray detection of the same period.
Koji Mukai, Updated 2007 November (originally written 2002 February).
Please send your comments, suggestions etc. to
Koji.Mukai@nasa.gov
and/or
Koji.Mukai@umbc.edu
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