Symbiotic variable AS 270 in outburst

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Symbiotic variable AS 270 in outburst

文章 PTS » 週四 14 11月, 2013 09:26

AAVSO Special Notice #375

Symbiotic variable AS 270 in outburst
November 13, 2013

The symbiotic star AS 270 is in outburst, according to observations reported to vsnet-alert by Berto Monard (MLF; Calitzdorp, South
Africa) and to the AAVSO International Database (AID) by Steve O'Connor (OCN; St. George's, Bermuda). O'Connor reports the star at
V=11.72 +/-0.03 on 2013 November 13.405 UT (JD 2456609.905), well above its normal minimum magnitude of 14.2V.

According to the AID, the last full outburst of AS 270 (and the only one recorded there until now) occurred in late August 2001, when the star reached visual magnitude 10.8 on 2001 September
10.5167 (JD 2452163.0167) (NLX, Peter Nelson; Ellinbank, Victoria, Australia). AS 270 was brighter than V=13 for well over 30 days, but the duration of the outburst is not known due to the end of the observing season. As of 2002 April 25.3111 and 25.3208
(2452389.8111 and 2452389.8208) it was 12.93V and 11.79R, respectively (O'Connor).

From 2005 July 4.2347 (2453555.7347, O'Connor) to August 2012 observations of AS 270 by O'Connor and Shawn Dvorak (DKS, Clermont,
FL) showed normal minimum behavior, varying between 13.5 and 14.2V.
In August-October 2012 it brightened from 14.04V to 13.32V
(O'Connor) before being lost behind the Sun. By 2013 February 13
(2456337.031) it was back to 14.23V (O'Connor).

From late June to early July 2013 AS 270 brightened to 13.6V (AAVSO Special Notice #366), then dipped a bit and brightened again to about 13.5V by late August, returning back to 13.8V by mid-October (BHQ, Terry Bohlsen, Armitage, NSW, Australia; Josch Hambsch (see below); Michael Heald (see below); Kevin Hills (see below); LMK, Michael Linnolt, Ocean View, HI; Monard (see below); Nelson (see above); PEX, Andrew Pearce, Nedlands, W. Australia; O'Connor (see above); WLY, Larry Wade, Belzoni, MS). Observations October 18-21 by Hambsch, Heald, and Hills show slow brightening from 13.806 to 13.624. The most recent observations reported to the AAVSO show it brightening more rapidly and include:

2013 Oct. 22.98849 UT, 13.089 V +/-0.009 (J. Hambsch, Mol, Belgium); 22.98907, 13.074 V +/-0.008 (Hambsch); 23.80, 12.89 V (B. Monard, Calitzdorp, South Africa, via vsnet-alert); 23.98859, 12.983 V +/-0.010 (Hambsch); 23.98917, 12.982 V +/-0.013 (Hambsch); 24.45182, 12.944 V +/-0.149 (Hambsch); 24.45327, 14.061 B +/-0.100 (Hambsch); 24.45472, 9.729 I +/-0.025 (Hambsch); 24.98940, 12.859 V +/-0.008 (Hambsch); 24.98998, 12.852 V +/-0.008 (Hambsch); 25.43001, 12.679 V +/-0.054 (K. Hills, Hartford, England); 26.44581, 12.713 V +/-0.052 (Hills); 28.80, 12.58 V (Monard, via vsnet-alert); 29.44686, 12.526 V +/-0.044 (Hills); 30.43764, 12.463 V +/-0.045 (Hills); 31.43949, 12.623 V +/-0.026 (Hills); Nov. 01.44749, 12.570 V +/-0.098 (M. Heald, US Military); 01.44894, 13.515 B +/-0.141 (Heald); 01.45040, 9.657 I +/-0.055 (Heald); 03.44248, 12.109 V +/-0.043 (Hills); 03.80, 12.09 V (Monard); 04.43743, 12.038 V +/-0.034 (Hills); 06.40100, 11.94 V +/-0.04 (S. O'Connor, St. Georges, Bermuda); 06.40200, 13.15 B +/-0.09 (O'Connor); 09.39500, 11.83 V +/-0.04 (O'Connor); 09.39800, 11.88 V +/-0.04 (O'Connor); 09.39800, 13.02 B +/-0.05 (O'Connor); 09.39900, 13.02 B +/-0.04 (O'Connor); 09.40000, 10.63 R +/-0.03 (O'Connor); 09.40400, 11.82 V +/-0.06 (O'Connor); 09.40500, 11.86 V +/-0.04 (O'Connor); 12.40800, 11.71 V +/-0.05 (O'Connor); 12.41300, 12.94 B +/-0.03 (O'Connor); 12.41400, 10.50 R +/-0.1 (O'Connor); 13.40500, 11.72 V +/-0.03 (O'Connor);

Visual and CCD observations are requested, with V band and transformed multicolor photometry (especially Johnson B) encouraged.

Coordinates (2000.0): R.A. 18 05 33.73 Dec. -20 20 38.1

Charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).

Please report observations as soon as possible to the AAVSO International Database using the name AS 270.

Many thanks to Berto and Steve for alerting the community to this stellar activity!

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.
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