The longterm (4.9 mag) periodic binary system VV Cep (primary component = M type, secondary component Be-star with disk) is one of my program star since 1996 (fig.1). After the eclipse in 1997-1999 particularly the Halpha V/R ratio of the Be-star disk is one of my special interest (fig.2).
Recently a period analysis reveals three periods of V/R (fig. 3), but this result is not sufficiently reliably. The observation frequency has to be higher.
Because of this situation I'm looking for observers who are interested to take part at this project. In case of interest please contact me.
Ernst
I am currently planning on dedicating a great time of my summer to spectroscopy. However, I am still putting my LhiresIII spectroscope in working condition, and still have not processed any spectra. I am still a beginner in spectra processing. I hope to start testing my equipment on the sky later this month, and be operational in July. However, I do not have an observatory, and will need to assemble and take apart every night I observe. HR 8383 is circumpolar from my location, varying from 13 to 65 degrees altitude.. It is in a nice location in the sky for the final part of the night.
What wavelength and desired resolution will you be looking for observation?
I have an 8.3" cassegrain (F/12.4), a LhiresIII with 2400 l/mm grating, and a KAF-3200 sensor. I also have a 300l/mm grating for lower resolution. Currently my neon lamp is not-operational, but that should be fixed soon. I will also be having an argon lamp for callibration.
If you do not mind in admitting a learning observer, I would love to participate and learn!
Fil
Your readiness to take part is really great. For requirements see my attached last spectrum as a template. To determine the S/N is somewhat difficult, because of the strong presence of the metal lines. But approximately 100 should be sufficiently.The usage of the 2400 grating would be fine, the star is bright enough for this relatively large dispersion. But on the other side it is helpfull for the separation of the double peak. It would be a great pleasure for me, to have you as member at this campaign. Let me know, if you want to learn more of VV Cep.
Ernst
Many thanks to Thierry and Filipe for your readiness of cooperation in the VV Cep project campaign. The desired higher observation density is naturally very much easier to realize in a larger observation community. But we have to be patiently for getting results. It take some time for calculating a new period analysis of V/R.
Ernst
The paper of Hutchings & Wright (Mon. Not. R. astr.Soc., 1971, 155, 203-214) is saying, that the secondary is already known as an Be-typ star since the eclipse 1956-58. Many scientists showed a strong interest for the nature of the hot companion during the last decades. Nevertheless its spectral type and temperature remain, even today, very ambiguous. Estimates are ranging from an early B- or O-type to an A0 star.
The hot B0 companion circles the M2 super giant with a radius of about 13 solar diameter at a mean distance of about 19-20 AU with a period of 20.4 years, an eccentricity e = 0,34-0,35 and an inclination of 76-77° with the unusual fact to be surrounded by an extended hydrogen cloud.
Spectroscopic investigations revealed, that this hydrogen disk with its diameter of 3 AU can be explained by mass transfer between the stars or mass ejections of the M-star, even though there is a large mean distance of 19-20 AU between them. According to investigations of (Wright 1977) the mass of the M-star and the Be-star is determined to be approx. 20 solar masses.
Ernst
Perhaps it is not included in the database because the disc appears to be formed by accretion rather than being self generated. An interesting system. I will try to take a look at it before the next eclipse
Robin
Well, I am not sure that I "need" an Argon lamp.. I am just in a quest for more and more lines that I could possibly use for calibration.. It
is more like an "exploration".. I was actually interested in lines over 7000 angstroms, so that is how the Argon came to mind.. However,
I just read about Robin's measurements of lines in the Neon lamp from the LhiresIII and he mentioned some Argon ones.. This has mostly to
do with me exploring stuff.. I will only have my Neon lamp working this weekend, hopefully. The next thing I will do is a run through all
wavelengths, from UV to IR, noting down the micrometer position and the spectrum region.
Fil
It seems there is a similarity between eps aur and VV cep. the eclipsing period are of the same order and only the center star seems to be different, a M super-giant for VV cep and a F, if so, super-giant for eps aur. But on the hypothesis that both system have B stars secondary components, embedded in a different cloud nature, some analogy in the Ha behavior and others lines mays be interesting to found. Even probing the HII region around primary maybe interesting to compare. It is why i began a long term survey with Ernst, following the near to end eps aur campaing.
Thierry
Beside the V/R monitoring for a period analysis, one of the main challange is, for professionals and amateurs as well, to find spectral signatures of the companion.Until now no one did find any hints in this direction.Maybe that the usage of (your) echelle spectrograph provides possibilities to find some signs in this way.
Ernst
As you may know, I prepared my LHIRES for the del Sco campaign, to work in all wavelengths that the Filly lamp allows, namely the HeII 4686 Ang. line. At the Miroshnishenko page, he mentions that a possible signature of the companion is in the 4460-4490 domain http://www.uncg.edu/~a_mirosh/Delta_Sco ... _B0_B3.pdf
As I can collaborate with your VV Cep monitoring after the del Sco campaign, what are the wavelengths that may contain the signature of the VV Cep companion?
Jose
My colleague B. Hassforther from the German Association of Variable Stars (BAV) and me have used his data and your PEP data in terms of the period analysis, what I mentioned here. But we couldn't find any connection to the quasi periodic behavior of the companion´s disk. Maybe PEP data in the future will contribute to a clarification in this sense.
Ernst
Your question to certain spectral signatures of the companion is a difficult question. Nobody knows what it could be nowadays. But at present the companion is on its way to the apastron, so, theoretical is there a chance with echelle spectrographs, when we subtract a typically M-typ spectrum from the entire VV-cep system spectrum, in order to investigate particularly within the blue region, where the contribution of the M supergiant is close to zero.
Ernst
This can be a chalenge for the LHIRES, but anyway I'll give it a try! The issue here is to get a very precise wavelength calibration, without the telluric lines, only based on the Filly lamp. A refference star is needed in order to correct eventual shifts on the lamp spectrum. Well, after the del Sco campaign let's try this chalenge.
Jose
Again, I am available, if I do not have to change my setup too much (not changing slit or grating) compared to VV Cep observations. I also have not practiced taking flats for spectroscopy, so I am uncertain how easy it will be to observe different portions of the spectrum with a LhiresIII + 2400 l/mm grating. I am still in the process of fixing my camera to the LhiresIII. Perhaps during the first weekend of Jully, I will be able to do my spectroscopic firstlight with the 2400 L/mm grating.
Fil.
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Ernst Pollmann
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Active Spectroscopy in Astronomy
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