V455 And
V515 And
AE Aqr
FO Aqr
V349 Aqr
XY Ari
V405 Aur
V647 Aur
HT Cam
MU Cam
DW Cnc
V709 Cas
V1025 Cen
V1033 Cas
TV Col
TX Col
UU Col
V2069 Cyg
V2306 Cyg
DO Dra
PQ Gem
V418 Gem
DQ Her
V1323 Her
V1460 Her
V1674 Her
EX Hya
NY Lup
V2400 Oph
V2731 Oph
V3037 Oph
V598 Peg
GK Per
AO Psc
HZ Pup
V667 Pup
WX Pyx
V1223 Sgr
V4743 Sgr
CC Scl
V1062 Tau
AX J1740.1
AX J1832.3
AX J1853.3
CTCV J2056
CXO J174954
IGR J04571
IGR J08390
IGR J15094
IGR J16500
IGR J16547
IGR J17014
IGR J17195
IGR J18151
IGR J18173
IGR J18308
IGR J19267
PBC J0927.8
PBC J1841.1
RX J1804
RX J2015
RX J2113
RX J2133
RX J2306
Swift J0717
Swift J1839
Swift J2006
Swift J2138

Full Catalog

Related Systems

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Related Systems

Asynchronous Polars

BY Cam, V1500 Cyg, CD Ind, V1432 Aql, and IGR J19552+0044 are (candidate) asynchronous polars. Although the spin and orbital periods are different in these systems, the differences are small (of order 1% or less), and they are thought to be in a state of temporary asynchronism. Therefore, I will treat them differently from IPs, in which the spin periods are generally thought to be near the equilibrium values.

1RXS J052430.2+424449, nicknamed "Paloma" is a case in between asynchronous polars and normal IPs. I'm now inclined to consider this a low-luminosity, diskless IP, since its synchornization timescale is very long. 1RXS J083842.1-282723 appears to be a case similar to Paloma. If we define APs as polars temporarily dislodged from synchronous rotation, this should be considered an IP.


There is no doubt V471 Tau is a binary consisting of a red dwarf and a white dwarf, and the latter is undoubtedly asynchronously rotating and magnetic. However, accretion appears to be sporadic, at an extremely low level, or both. I prefer to define IPs such that only systems in which accretion usually provides a measurable fraction of the luminosity are included.

Recently, Wilson et al. (2021, MNRAS, 508, 561) announced that CC Cet is a pre-IP.

AR Sco

Again, there is no doubt this is a binary consisting of an M dwarf and an asynchronously rotating magnetic white dwarf. However, so far, there is no indication that accretion currently plays any role in this system, with all non-stellar radiation being attributed to a pulsar-like mechanism and is rotation-powered. While there is a strong similarity to IPs, particularly AE Aqr, it's probably best not to include this among IPs, unless a non-negligible fraction of its luminosity turns out to be accretion powered.

Z And

The coherent 25 min period found in this system appears convincing (although we could always use confirmation). I do not include this system because it is an symbiotic star with an M giant mass donor.

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Please send your comments, suggestions etc. to Koji.Mukai@nasa.gov and/or Koji.Mukai@umbc.edu
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