(cba:news) msp binaries, candidates, and others

Joe Patterson jop at astro.columbia.edu
Sat Mar 1 16:03:29 EST 2014

Dear CBAers,

There's a new class of interacting binaries in town.

About ten years ago a few papers were written about a peculiar star, a 
CV-look-alike some of the time.  I attach the one written by Thorstensen 
& Armstrong.  The star turns out to be also a gamma-ray source and 
millisecond pulsar!

There are two other known stars of this type.  One is in M28, not 
readily observable by earthbound telescopes.  The two that can be 
observed are listed below.  They're usually in the range 17-18 mag - no 
picnic - but very little is yet known about the magnitude variations of 
this new type of compact binary.  Outbursts, low states, recurrence 
periods... we're mostly ignorant concerning all these matters - that 
we'd like to know, and that we might well find out.

In addition, there are two other stars that live in quite small Fermi 
error circles, and that have spectra resembling CVs.  Are they CVs?  Are 
they gamma-ray sources, or are they in Fermi error circles by accident? 
  And are they millisecond pulsars?  We don't know any of the answers... 
but we might learn plenty from studying the nightly light curves.

Since this subject is so new, we don't exactly know how to observe these 
stars.  Fast, slow, once a night, long time series... who knows?
The CBA is in a pretty good position to explore this subject.

See what you can find out!  Their charts and positions are attached and 

Re other stars, we're finished with CP Puppis and V745 Sco.  AM CVn is 
going well... and may it continue!  I'm hoping for more action on V406 
Vir - and BK Lyn, too.

joe p

-------- Original Message --------
Return-Path: <jules at astro.columbia.edu>

Millisecond Pulsars/LMXBs in transition

  PSR J1023+0038    10 23 47.6  +00 38 41.0    2000.0
  Chart reference  http://adsabs.harvard.edu/abs/2005AJ....130..759T

  XSS J12270-4859   12 27 58.75 -48 53 42.9    2000.0
  Chart Reference  http://adsabs.harvard.edu/abs/2006A%26A...459...21M

CVs in Fermi Error Circles

  1RXS J083842.1-282723   08 38 43.47 -28 27 01.5    2000.0
  Swift J1544.6-1128      15 44 39.3  -11 28 04.0    2000.0

  Chart reference    none (see attached)
  Spectrum reference http://adsabs.harvard.edu/abs/2013A%26A...559A..58M

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