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Alert Notice 486: Spectroscopy and photometry campaign on three bright Wolf Rayet stars

June 26, 2013: Dr. Noel Richardson (Université de Montréal) is helping coordinate a very large ProAm campaign (over 20 professional and amateur astronomers) this summer on three bright Wolf Rayet stars in Cygnus. Dr. Richardson, fellow co-PIs Drs. Tony Moffat (Université de Montréal), Nicole St.-Louis (Université de Montréal), and Thomas Eversberg (Schnoerringen Telescope Science Institute, Waldbroel, Germany), and their colleagues invite AAVSO spectroscopists and photometrists to participate in this campaign.

The targets are WR 134, WR 135, and WR 137 (HD 191765, HD 192103, and HD 192641), which happen to be the first three WR stars discovered from visual spectroscopy by Wolf and Rayet. This campaign has been underway since mid-May and will continue through September 17, 2013.

MAIN CAMPAIGN GOAL
Dr. Richardson writes: "Our main goal is to collect a densely-sampled (in time) spectroscopic (and photometric) data set of WR 134, WR 135, and WR 137, which all lie within about ~0.5 deg in the sky. We wish to probe the clumping aspects of the strong winds (WR 135 has the clearest signature of clumps in the optical spectrum) and examine the changes that are present in large structures in the stellar winds (WR 134 and WR 137). We have managed to secure 4 months of observing time with only a few off-nights at the 0.8m telescope at Teide [Observatory, Tenerife, Canary Islands]. Amateur spectroscopists around the world have also volunteered to observe these stars during the time span of the campaign in order to get better time coverage of the stars, often using their ~10-15in telescopes with LHIRES spectrographs or the echelle spectrographs available as off-the-shelf equipment.

"Details of the campaign are available here (with links to information regarding the data acquisition): http://www.stsci.de/wr134/index.htm

SPECTROSCOPY
"AAVSO spectroscopists can provide a wonderful addition to the data. Especially in North America, we have few spectroscopic observers [already participating]. Spectroscopy...[should focus especially on] the HeII 5411A line in WR134 and the CIII 5696A line in WR135 and WR 137, where the small emission bumps we are looking for are easiest to spot)...We request 1 A resolution and high S/N >= 200." Exposure times for one complete observation should be no longer than 1 hour for each star."

The project website adds: "A telluric standard star nearby in the sky (alpha Leo or zeta Aql) should also be observed occasionally in order to be able to subtract out these nuisance terrestrial atmospheric features in the stellar spectra. We also need occasional observations of a star with a relatively flat spectrum (delta Sgr or beta Aqr) to correct for any instrumental effect (if possible for a given observer)."

PHOTOMETRY
Dr. Richardson continues: "In addition, filtered photometry of the variable WR stars provides excellent constraints on the wind variability, which has been shown through the MOST campaigns by Anthony Moffat and his collaborators. Therefore, we welcome and encourage filtered UBVRI observations regularly during the campaign. I think time-series are more important than single snap shots. However, all of it throughout the campaign will be useful, especially if the S/N is greater than 100-200. We ask for the highest possible accuracy up to the milli-mag level.  

SUPPLEMENTAL TARGETS
"There are two supplemental targets to be observed if time permits, V905 Sco (HD 160529) and V4375 Sgr (HD 316285). They are being observed by MOST this summer to study pulsations of these rare Luminous Blue Variables. They will be observed through the end of July and multi-color photometry would be useful."

Star HD Spec.Type RA(2000) Dec(2000) V B-V
WR 134 191765 WN6 20 10 14.20 +36 10 35.1 8.23 +0.20
WR 135 192103 WC8 20 11 53.53 +36 11 50.6 8.36 -0.03
WR 137 192641 WC7pd+O9 20 14 31.77 +36 39 39.6 8.15 +0.14
V905 Sco 160529 B8-A9Ia+ 17 41 59.03 -33 30 6.21 +1.04
V4375 Sgr 316285 B0Ieq 17 48 14.04 -28 00 9.03 +1.5
alf Leo 87901 B9IVn 10 08 22.31 +11 58 02.0 1.4 -0.16
zet Aql 177724 A0Vn 19 05 24.6 +13 51 48.5 3.0 +0.028
del Sgr 168454 K3III 18 20 59.64 -29 49 41.2 2.7 +1.414
bet Aqr 204867 G0Ib 21 31 33.5 -05 34 16.2 2.9 +0.83


Finder charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Please note that AAVSO sequences for V905 Sco and V4375 Sgr are not yet available but will be added and announced.

Please submit photometry to the AAVSO International Database using the names WR 134, WR 135, WR 137, V905 SCO, and V4375 SGR, respectively. Instructions for sending spectroscopy data to Dr. Richardson may be found on the project website at http://www.stsci.de/wr134/pdf/data_transfer.pdf.

This observing campaign is being followed on the AAVSO Observing Campaigns page (http://www.aavso.org/observing-campaigns).

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