Spectrum of a candidate PN
Posted: Sat Nov 17, 2018 9:57 am
Hello
Here is the spectrum of a candidate PN discovered by Matthias Kronberger : Kn 131.
More information "et en français" here
According the observed lines, the object is a PN.
The (noisy) He II line indicates that the central star is hot.
Taking a spectrum of this kind of object is quite challenging because it's very faint.
image KNPO.
Despite the bad resolution and the bad signal/noise ratio of the spectrum, I tried to make a measure of the extinction coefficient of the PN and determine its excitation class.
The analysis relies on the intensity of Ha, Hb, He II and [O III] lines.
Ha and the [N III] are totally blended due to the poor resolution... So I used Excel to fit the blended profile with 3 gaussians.
What kind of tools do you use for gaussian fitting (vspec ?) ?
I've found a balmer decrement of 3,5. That is quite high compared to other PNe (~3.0), but not impossible. The corresponding extinction coefficient is c(Hb)=0,31.
The values aren't very reliable because of the poor quality of the acquired data. The important point to note is that the PN seems to be quite reddened by the interstellar matter.
Thanks to the extinction coefficient, it's possible to derreden the lines ans determine the excitation class of the PN.
I found an high excitation class. (EC : 7~11)
The central of the PN seems to be very hot (100 000 K - 200 000 K).
Here is the spectrum of a candidate PN discovered by Matthias Kronberger : Kn 131.
More information "et en français" here
According the observed lines, the object is a PN.
The (noisy) He II line indicates that the central star is hot.
Taking a spectrum of this kind of object is quite challenging because it's very faint.
image KNPO.
Despite the bad resolution and the bad signal/noise ratio of the spectrum, I tried to make a measure of the extinction coefficient of the PN and determine its excitation class.
The analysis relies on the intensity of Ha, Hb, He II and [O III] lines.
Ha and the [N III] are totally blended due to the poor resolution... So I used Excel to fit the blended profile with 3 gaussians.
What kind of tools do you use for gaussian fitting (vspec ?) ?
I've found a balmer decrement of 3,5. That is quite high compared to other PNe (~3.0), but not impossible. The corresponding extinction coefficient is c(Hb)=0,31.
The values aren't very reliable because of the poor quality of the acquired data. The important point to note is that the PN seems to be quite reddened by the interstellar matter.
Thanks to the extinction coefficient, it's possible to derreden the lines ans determine the excitation class of the PN.
I found an high excitation class. (EC : 7~11)
The central of the PN seems to be very hot (100 000 K - 200 000 K).