Halpha observation

VV Cep 2017-2019 Campaign
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Ernst Pollmann
Posts: 461
Joined: Mon Sep 26, 2011 7:16 pm

Halpha observation

Post by Ernst Pollmann »

Some observations goals of interest around the Halpha area:

Halpha equivalent width:
we can understand the EW of the Halpha line profile (among others) as indicator of the mass lost rate of the M type star into the accretion disk of the B star. The discussion with Phil Bennet about my EW measurements during the last (approx.) 20 years leads to the assumption, that the mass loss rate (EW-scatter out side the eclipse) is of stochastic character (see the attached EW monitoring). During the coming years it is of certain interest, to monitor the EW on short time scales in order to find out any periodicities if there are (one spectrum per week).

V/R variability:
the Halpha profile is devided by a central absorption core. This absorption is caused of the amount of neutral hydrogen gas in the outer (cool) region of the accretion disk around the B star, from the super-giant itself, and from the hydrogen cloud which surrounds the whole system. Because of the orbital movement of the B star and its disk, we have to expect a certain variability of the radial velocity (dependently of the orbit) of the central absorption core.
(see the attached radial velocity plot). That's why we can observe a corresponding variation of the V/R ratio (see the attached V/R montoring).
The question is, is there in addition a further influence on the V/R ratio? There is a statement from a professional astronomer, that the violett component (V-peak) has been always stronger than the red component (R-peak) of the profile. If so, why? A larger density (or temperature) of the accretion disk in the area, which rotates in the line of sight towards us?

Ernst
Attachments
vvcep_EW.jpg
vvcep_EW.jpg (69.62 KiB) Viewed 3573 times
vvcep_VtoR.jpg
vvcep_VtoR.jpg (77.52 KiB) Viewed 3573 times
RV-versus-Phase.png
RV-versus-Phase.png (142.61 KiB) Viewed 3573 times
Last edited by Ernst Pollmann on Tue Sep 01, 2015 8:31 am, edited 2 times in total.
Ernst Pollmann
Posts: 461
Joined: Mon Sep 26, 2011 7:16 pm

Re: Halpha observation

Post by Ernst Pollmann »

Here a self-describing operational sequence to the evaluation of equivalent width and V/R ratio.

Ernst
Attachments
VVCEP_evaluation.png
VVCEP_evaluation.png (202.97 KiB) Viewed 3639 times
Benjamin Mauclaire
Posts: 258
Joined: Thu Sep 29, 2011 10:14 am

Re: Halpha observation

Post by Benjamin Mauclaire »

Hello,

For EW computation, SpcAudace extracts the continuum and compute EW at once by using spc_ew.
It's well described here http://wsdiscovery.free.fr/spcaudace/news/opus/#ew.

This avoid errors from user on how to extract continuum and moreover it computes uncertity at the same time, as always for any scientific measurements.

For V/R, it does gaussien fitting on the two lines compenents that are specified. See http://wsdiscovery.free.fr/spcaudace/do ... vr_mes.png

Benji
Spcaudace spectroscopy software: saving you hundred hours of frustration.
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