P cygni at R=110k

[Alexandre Santerne]

Dear all,

Following the observation of P cygni by all the spectrographs this summer during the OHP workshop, where I observed the star with SOPHIE, I renew the observation last night with the HARPS-N spectrograph. This spectrograph is mounted at the 3.6-m telescope TNG, the italian telescope at La Palma. It's a copy of the ESO one, mounted at the 3.6-m telescope at La Silla, and has a resolution of 110 000.

We just used one minute to secure a high-resolution, high signal-to-noise spectrum of P Cygni.
For those who are interested, you can find this spectrum here:
https://www.dropbox.com/s/m7z163pugitc1 ... .fits?dl=0

Below is a comparison of the H-alpha line between the SOPHIE and the HARPS-N spectra.

Halpha_HARPS-N.jpg (42.91 KiB) Viewed 7789 times

Of course, the difference is not really impressive. The reason is that the shape of the P-cygni profile is already resolved at the resolution of SOPHIE (R=75k). The comparison with the VHIRES at R=50k would produced also similar results.

Pro/Am collaboration could also be Pros observing for Ams

cheers,

Alex

[Alexandre Santerne]

Dear all,

Since the Halpha profile present very similar profile, I checked other spectral domains which present some differences:

line1.jpg (18.81 KiB) Viewed 7731 times

line2.jpg (19.84 KiB) Viewed 7731 times

line3.jpg (23.53 KiB) Viewed 7731 times

line4.jpg (32.54 KiB) Viewed 7731 times

I have no idea why those lines present a different profile between the two spectra, while the Halpha is the same.
Maybe the monitoring of P-cygni would be more interesting in those lines...

Good luck to understand these features...

cheers,
Alex

[Christian Buil]

Some unpublished spectra of P Cyg taken with VHIRES spectrograph + C11 at R = 50000 taken in the second part of this year:



(the H2O telluric lines are removed and heliocentric velocity corrected)

The measured Ha EW from these data:

24.979/07/2014 -> EW = 64.1 A
29.954/07/2014 -> EW = 66.0 A
13.966/08/2014 -> EW = 62.7 A
25.836/09/2014 -> EW = 56.0 A
01.798/10/2014 -> EW = 54.0 A
05.791/10/2014 -> EW = 52.4 A
29.775/10/2014 -> EW = 53.7 A

Fast change on the Halpha profile:



and long term evolution:



Christian B

[Ernst Pollmann]

Dear colleagues,
some remarks to the Halpha line profile in P Cygni:

The Halpha line profile is shaped:

1) by a compound radiation of recombination and ionisation of the wind (latter caused by the central star, Teff ~ 21000 K),

2) by an emissivity of the non-coherent electron scattering (see Najarro, Hillier, Stahl; A&A, 326, 1117-1134), and

3) by the wind (self)-absorption process in the line of sight of the observer.

Small changes in luminosity and / or mass can lead to a dramatic switch of the ionisation structure of H (and He) in the wind.

Attached you can find a plot, where these three contributions are modeled by using of a simple Gaussian distribution. The edges (wings) of the Halpha profile are essentially dominated by electron scattering (see Najarro, Hillier, Stahl; A&A, 326, 1117-1134). The high velocity dispersion of the electron scattering, leads to a wide profile expansion on the wavelength scale. Depending on its intensity, this range can reach from 6515 to 6610 Å.
That means, the EW evaluation of the Halpha profile should be performed at least within this wavelength range (see the attached long-term monitoring of the campaign). The spectrum of my 2011-09-05 observation shows very clear this wide wavelength range of the electron-scattering contribution.

Ernst Pollmann

[Ernst Pollmann]

Maybe it's interesting to show in this context, that the wind density is really dramatically changing sometimes. This is clearly to see, at the intensity of the blue-shifted absorption component of Halpha in my attached spectra from December 2008.

Ernst Pollmann