[vsnet-alert 1652] CI Cam (XTE J0421+560) (Hjellming)

[Taichi Kato <tkato>]

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Date: Tue, 07 Apr 1998 13:20:49 -0600
To: "Robert M. Hjellming (Bob)" <rhjellmi@nrao.edu>,
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From: "Robert M. Hjellming (Bob)" <rhjellmi@aoc.nrao.edu>
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Subject: [vsnet-alert 0] copy of IAU Circular submission on radio jets in XTE J0421+560
  (= CI Cam)
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Date: Tue, 07 Apr 1998 12:57:49 -0600







To: BMARSDEN@CFA.HARVARD.EDU, DGREEN@CFA.HARVARD.EDU
From: "Robert M. Hjellming (Bob)" <rhjellmi@nrao.edu>
Subject: IAU Circular submission on XTE J0421+560 and CI Cam
Cc: rhjellmi, amiodusz

XTE J0421+560 AND CI CAMELOPARDALIS

R.M. Hjellming and A.J. Mioduszewski, National Radio Astronomy Observatory,
report: "VLA images at 22.5 GHz made April 5.08 and April 6.94 UT
show that the CI Cam radio source had become resolved.  The extended
emission was just becoming apparent April 5.08, and by April 6.94
it had the appearance of a roughly symmetrical S-shaped twin-jet, 
strikingly similar to the radio jets of SS433.  The outermost pair
of emission components was separated by about 0".33 on April 6.94, so 
if one assumes a beginning at the start of the X-ray outburst on 
March 31.6, the proper motion of each component is 26 mas per day.  
Assuming a distance of 1 kpc (Chkhikvadze (1970) as quoted by Bergner et al.
(A&AS, 112, 221, 1995), this corresponds to apparent tangential velocities 
of 0.15c. The values of proper motion and apparent tangential velocity
may be larger if jet ejection occured after the beginning of the
X-ray outburst. Better constraints on these values will be obtained 
after analysis of a series of images. The presence of relativistic 
jets from CI Cam supports its identification with XTE J0421+560."




At 06:56 PM 4/3/98 -0700, Robert M. Hjellming (Bob) wrote:
>The following submission to the IAU Circulars describes
>our current conclusion from the VLA data of April 2 and 3.
>There will be a long VLBA imaging run on this source 
>tomorrow.
>
>If you plot the radio spectra you will see why this
>is an EXCEPTIONALLY quickly evolving synchrotron radiation
>source.
>
>>Date: Fri, 03 Apr 1998 17:38:13 -0700
>>To: BMARSDEN@CFA.HARVARD.EDU, DGREEN@CFA.HARVARD.EDU
>>From: "Robert M. Hjellming (Bob)" <rhjellmi@nrao.edu>
>>Subject: IAU Circular submission on XTE J0421+560 (= CI Cam)
>>Cc: rhjellmi, amiodusz
>>
>>
>>XTE J0421+560 AND CI CAMELOPARDALIS
>>
>> R. M. Hjellming and A. J. Mioduszewski, National Radio
>>Astronomy Observatory, report: "VLA observations of 
>>CI Cam on Apr 3.83 UT reveal the presence of an 
>>unresolved point source with preliminary flux densities 
>>of 120, 470, 650, 500, and 420 mJy at 1.4, 4.9, 8.4, 
>>14.9, and 22.5 GHz, respectively.  This indicates that 
>>it was optically thick at the two lower frequencies 
>>and close to optically thin at the two higher frequencies. 
>>The size of the source is less than 0.1" at 22.5 GHz.
>>We reanalyzed the 1.4 GHz data for April 2.63 UT (IAUC 6827) 
>>and were able to also image the source at 4.9 and 8.4 GHz, 
>>so we can report preliminary flux densities of 20, 150, and 
>>280 mJy at these three frequencies on April 2.63 UT; at 
>>that time the spectrum was optically thick with a spectral 
>>index of about 1.5. The rapid variability of factors of ~6, 
>>~3, and ~2.3 at 1.4, 4.9, and 8.4 GHz, respectively, 
>>indicates that this is synchrotron radio emission which 
>>is probably related to the X-ray transient XTE J0421+560 
>>(IAUC 6855,6857).  Since the position of the unusual
>>radio source coincides with the "symbiotic" star CI Cam, 
>>the radio emission and X-ray transient can both be 
>>identified with CI Cam."  
>>
>>
>>
>>
>
>

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