[vsnet-chat 7571] HD 347929 RFO - was Re: is this thing on?

[substellar at Safe-mail.net]

> testing, testing, 1, 2, 3, 4.
> 
> I dunno, I didn't think I'd done anything to get banned this time.

Great, so what happened to the one about the markedly period declining T Tauri star with xray outbursts that I sent yesterday then?  I forgot to save that one in the sent folder, so that's gotten lost.

Basically HD 347929 seriously needs monitoring.  Some bumf can be found at simbad.  It's a starspot T Tau, monotonically declining period (about half a day or so in five years), monotonically increasing amplitude and declining mean magnitude, possible recent onset of eclipses, potentially via accretion disc, but asas3 data is well lagged, maybes KH15 D-ness, maybes not.  ATEL 2700 and 2701 too.  HST project gives spectrum K4 V-IV.  Direct reference links in original email if it turns up.  Pretty much unique object, changing all the while.  I say unique, I don't know the nitty gritty of every single variable YSO going, they're a diverse bunch.  Last measurable period around 32.9 days, might be less now, last online amplitude about 1.0 V (far too big for just starspots, but still with rotator lightcurve profile), during recent asas3 glitch when asas north plots up to current time were being returned publicly it looked like it had got to 1.5 V ampltiude and the minimum looked a bit eclipsey profiled, but only online graph available, no data download, and then they fixed the glitch.

Potentially a star speeding up under increased accretion rate, gaining angular momentum therefrom and all that.  Needs monitoring, three images a night when possible (for redundancy, 2nd observation is a check in case of hot pixels, cosmic rays etc, but if observation 1 and 2 are discrepant, how to choose if intranight variation or error, well, a third observation will confirm one or t'other or show trend or flickering likeliness).

Visible from both hemispheres, should have a coupla more cycles at least left in it before observing season disappears.  Archive data at standard repositories, V filter preferred (the thing ain't white), it'll be there then if it is ever needed, and/or if any white light flare accompanies any further xray flare, coz if the increased amplitude is increased starspot coverage, and period decline does reflect angular momentum increase, and xray flare is chromospheric as per the ATELs (as opposed to from any accretion disc), then the chromosphere and photosphere are getting well churned up, and more flaring may be due.  Won't know if nobody looks.  If original email still in the works and just delayed in the cyber-aether and not fallen down some cyber blackhole, references and information not spouted from memory will appear.

Cheers

John