[vsnet-alert 2594] AB Aur (Ashok)

[Taichi Kato <tkato>]

Forwarded message from Dr. Ashok:

From ashok@prl.ernet.in Mon Feb  8 15:30 JST 1999
Date: Mon, 8 Feb 1999 12:00:15 +0530 (IST)
From: DR N M ASHOK 4002 <ashok@prl.ernet.in>
Subject: Information to be circulated in VSNET

N.M.Ashok of Physical Research Laboratory Ahmedabad 380009, India
requests for observations of the bright Herbig AeBe star AB Aur(HD 31293)
in recent months.
Our observations during Jan 9 - 15,1999 at near infrared and optical
wavelengths have shown decreased IR emission and increased optical
polarisation (IAUCirc 7103 Feb 2,1999 ).We will be monitoring this
interesting star in coming months and encourage obtaining optical
photometric observations.Any optical observations during Jan 9-15,1999
will be particularly valuable for us and I request persons having such
data to contact me at ashok@prl.ernet.in

----------------------------------------------------------------------------
Dr N.M.ASHOK                        e mail  :  ashok@prl.ernet.in
Astronomy & Astrophysics Divn       FAX     :  079-6560502
Physical Research Laboratory        Phone   :  079-6462129  (Navrangpura)
Navrangpura                                    079-6425037 (Thaltej)
Ahmedabad 380009                               079-405355  (Residence)
India
-----------------------------------------------------------------------------

From: ashok@prl.ernet.in
Date: Mon, 8 Feb 1999 12:06:06 +0530
Subject: IAUC 7103 text refering to AB Aur

 N.M.Ashok,T.Chandrasekhar of Physical Research Laboratory,Ahmedabad and
 H.C.Bhatt,P.Manoj of Indian Institute of Astrophysics,Bangalore report:

 AB Aur (HD 31293), one of the brightest and the prototype Herbig Ae/Be
 star, presently seems to have entered an unusually inactive phase. A near-
 infrared spectrum taken with Nearinfrared Imager/Spectrometer with
 256X256 HgCdTe NICMOS3 array on the 1.2m telescope at Mt.Abu Observatory
 of Physical Research Laboratory on 9 Jan 1999 shows that the Paschen Beta 
 line is marginally in absorption and the Brackett Gamma emission is absent. 
 Optical linear polarization measurements of AB Aur, made with a polarimeter 
 on the 1m telescope of the Indian institute of Astrophysics at Kavalur 
 on 15 January 1999 show that it's degree of polarization (P(V) =0.8 +- 0.1 %, 
 Theta = 70 +- 3 degrees) is now at its highest. The photometric magnitudes 
 are: V = 7.0 +- 0.1 (15 January), J, H, K (9 January) = 7.2 +-0.15 ,  
 6.4 +- 0.15 ,6.0 +- 0.15 .While its visual magnitude is at its brightest, 
 the infrared J, H, K magnitudes are at their faintest level, indicating
 substantial decrease in the near-infrared caused by any circumstellar dust.

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