Observation request: T Tau early in January

[Hans Moritz Guenther]

I have taken a brief look at the spectra in the database. Thank you so much, that is exactly what we hoped for.

We now have to compare the optical spectra with the Chandra data, but we have not received the Chandra data yet (it typically takes 2-3 weeks after the observation - there is a delay of 1-2 days until the data is downloaded to Earth and then a few days to two weeks for processing at the Chandra data center).

Christian Schneider (who is responsible for the Chandra observation) and I will update you in this thread once we know if there was any X-ray activity during the observation. There will be no more X-ray observations of T Tau in the forseeable future. This is already the second time that T Tau is observed in X-rays and observing time on X-ray telescopes is hard to get, because there are only two satellites in orbit that can do this type of observation (XMM-Newton and Chandra).

Personally, I think that T Tau is a very interesting star (actually, it is a multiple system, but most components are deeply embedded behind strong absorption and are not visible in the optical), but I am not sure if we learn a lot when we keep looking in the optical. All classical T Tauri stars are strongly H alpha variable, so I expect things to happen with T Tau, too.
Comparing Halpha with the X-ray data I knew that we were looking at something that nobody has ever done before for any massive T Tauri star. In my opinion it will be useful to keep looking at T Tau, but I cannot promise that we will find exciting new stuff.

Thank you again so much for all the data you have taken so far!

[Hans Moritz Guenther]

Other Chandra observations on this object are programmed? Do you think it is useful to intensively observe this star now?

Do you encourage this initiative ? It appears correct? Can you help for analyze the (potentials) results?

Some of this is answered in my previous post, but not all of it

So, one at a time
other Chandra observations: No

It is useful to intensify the campain now? I think such a campain would be very useful. However, the Chandra observations are over, so there is no immidiate need to do it "right now". I don't know very well where most of the you observers are located and at which time of the night you have most interest and time to do the observations. If you think that fall 2015 would be a better date because of the visibility, then you should consider that.

Do I encourage it? Definitely.

Can I help? I definitely will help with the analysis. Anything I can do to tease out more info about T Tauri stars!

[Robin Leadbeater]

Francois, Christian,

Did you receive my spectra? I have sent 125

Robin

[Francois Teyssier]

Robin,
I received nothing - Could you try again ?
François

[Christian Buil]

Many thanks Hans for the infos and suggestions!

Here a very long cumulative exposure time observation of T Tau taken the 5.7 January 2015 with VHIRES (R=48000) - 2 hours - not for time resolution analysis (the individual 10 minutes exposure seem show minor evolution during the run, but the SNR is low in the continuum - near 3 to 4 only per resolution element, but EW values extraction seem possible). The plot shows also the comparison with my 21 December 2014 spectrum:



Christian

[Hans Moritz Guenther]

I just wanted to share with you that we have now received the Chandra data. We thought it would be straigthforward to make a lightcurve to compare it with the H alpha equivalent width, but the data is better than we thought. T Tau N is actually a close binary itself separated be about 0.1 arcsec. The bright component contributes > 90% of the flux, and that's the star that almost certainly causes the H alpha emission. So we could just take the entire light observed and add that all up, but we try to do better!

In Chandra each individual pixel is about 0.5 arcsec on the side, so the separation is much less than one pixel. Still, we might be able to separate the two lightcurves. In X-rays we detect single photons and we essentially get a list of photons with the time, energy and the X,Y position of each photon on the detector. Now here is the trick: The detector is read out every 3.2 seconds and T Tau is so faint that in each frame we will see at most one photon. X-ray photons are so energetic that they leave a signal in more than one detector pixel. So we might see something like this:

0 1 0
1 6 1
0 1 0

In this case the photon probably hit the middle of the middle pixel. Or we might see something like this:

0 3 3
0 4 3
0 1 0

In this case, the photon probably hit the upper right corner of the middle pixel.
In this way we can measure the position of a pixel more preceise than the size of a pixel. Obviously, there is software to help with this, but we want to be careful and do things right, so it might take a little longer until I can show you a good (and correct) X-ray lightcurve here.

So this post is just to let you know that we are working on it, but have nothing to show yet.

[Robin Leadbeater]

Did anything come out of this work does anyone know?
http://www.astrosurf.com/aras/Aras_Data ... u/TTau.htm

Robin

[Hans Moritz Guenther]

Hi Robin,

Did anything come out of this work ?

A fair question given that it takes so long. I need to apologize, but we are still working on it. In addition to the XMM-Newton observations, we also got data with the Chandra X-ray telescope. We decided to wait for that (the observation happened in 2015) so that we could compare the two X-ray observations with each other. Christian Schneider is working on that data and send me a draft of his article just today. We plan to have that ready in the next few weeks and I'll share a summary here when we have it.

Moritz

[Robin Leadbeater]

Data Base updated with spectra from Peter, Paolo and Terry

http://www.astrosurf.com/aras/Aras_DataBase/Ttauri/T_Tau/TTau.htm

"TTauri" isn't "Ttauri" : thanks Paolo !



François

The link to these spectra in the ARAS database is broken and the button for T Tauri stars in the database here is not working.
http://www.astrosurf.com/aras/Aras_Data ... taBase.htm

Where can I find these spectra?

(For the record, my spectra and those of J G Flo can also be found in the BAA database)

Thanks
Robin

[James Foster]

Here is a Alpy600+LISA IR combined spectrum, shot receptively on 08 and 09 Dec 2018:

All identified lines are speculative, especially the SII lines shown.

James