Alert Notice 830: V347 Aur monitoring requested in support of XMM-Newton observations

July 19, 2023

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
 - Campaigns and Observing Reports: https://www.aavso.org/v-347-aur-campaign-2023
 - Young Stellar Objects: https://www.aavso.org/v-347-aur-campaign-2023-01

Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!

Drs. Michael Richmond (Rochester Institute of Technology) and Nicolas Grosso (Laboratoire d'Astrophysique de Marseille) request AAVSO observers' assistance in monitoring the Young Stellar Object V347 Aur in support of XMM-Newton observations scheduled for August and possibly October.

Dr. Richmond writes: "At a distance of ~204 pc, V347 Aur is centered in the L1438 Bok globule and illuminates at ∼10"─South a small, variable reflection nebula. V347 Aur is a young low-mass star (see the Young Stellar Object Program), transitioning between an evolved protostar and a classical T Tauri star that exhibits (quasi)periodic (~155 days) optical outburts, displaying in the V band peak amplitudes from ~1 to ~4 mag above the quiescent level at ~15.8 mag (Dahm & Hillenbrand 2020, AJ, 160, 278). These optical brightenings likely signal the onset of rapid mass-infalls, magnetically channelled from the accretion disk onto the stellar surface, which may also produce X-ray outbursts from star-disk magnetic interaction.

"We predict for V347 Aur an optical high-state in 2023 mid-August with a return to the quiescent phase in 2023 October. Our aim with the AAVSO observations is to monitor the long-timescale behavior of this outburst in the V and B bands and to compare it with: the V (plus U and B shorter) time series that will be obtained with the XMM-Newton Optical Monitor and the simultaneously X- ray emission that will be obtained with the XMM-Newton EPIC cameras.

"XMM-Newton observations will be scheduled on August 20, 2023, and if V347 Aur is detected in X-rays, also scheduled on October 1, 2023." (Watch the forum threads above for further information about the October observation.)

Beginning immediately, please observe V347 Aur a few times per night, with observations spaced about an hour apart to detect rise/decay trends. Please continue these observations on as many nights as possible until about one month after the second XMM-Newton observation (i.e., the expected campaign end date is November 1). Dr. Richmond asks for this cadence in order "to determine the shape of this outburst (the duration and intensity of the outbursts cannot be predicted)."

Johnson V and B (V prioritized) coverage is requested, with observers alternating between the two if possible to obtain nearly simultaneous B-V data. DSLR TB, TG, and TR observations are also welcome. Visual observations are also requested - even upper limits would be helpful. Unfiltered observations are NOT requested.

Comparison stars: Photometry observers (CCD/CMOS/DSLR) are requested to use ONLY the 154 comparison star circled on the accompanying chart image (the AUID of this 154 is 000-PPQ-528 in the photometry table for this chart). Visual observers will have to use the other comparison stars in the field, and should use the circled 154 when appropriate.
 
Spectroscopy is not requested for this campaign.

Coordinates (2000.0):  R.A. 04 56 57.02  Dec. +51 30 50.9   (from VSX entry for V347 Aur)

Finder charts for V347 Aur with comparison stars may be created using the AAVSO Variable Star Plotter (VSP). See text above about which comparison star(s) to use when.

Please submit your observations to the AAVSO using the name V347 AUR.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using information provided by Dr. Richmond.
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