7 replies to this topic

[brownrb1]

Hi,

Finally had a clear dark night last night. Besides some images of some DSO's I got some spectra. WR 140 is a type WC Wolf-Rayet star-which exhibit strong carbon and helium emission lines- and has a mass of about 14.9 solar masses and a temperature of about 70,000 K. I used a 10" Meade SCT, 0.5x reducer, Atik Infinity monochrome camera, and an Alpy 600. Campbell's hydrogen star ( PK 64+5.1) is a planetary nebula whose central star, as per the Chandrasekhar limit, is less than 1.4 solar masses. The hydrogen Balmer lines are pretty evident, but not sure of the other 2 prominent emission lines-the one at 6340 angstrom may be [0ll] ?.For this spectrum I used my SA-100 instead of my Alpy. I also,got a nice image and profile of Vega using 10"Meade, 0.5x Orion reducer, Atik Infinity mono camera and Alpy 600

Thanks

Dick

Edited by brownrb1, 07 October 2018 - 02:36 AM.

[Organic Astrochemist]

Nice spectra.
Although Campbell’s Hydrogen Star is one tenth the mass of WR140, it has a similar spectrum and is classified [WC 9].
As a result, it is a very hot star with copious UV emission shorter than 3000 angstroms. You don’t see these in your first order spectrum, but they appear at twice their wavelength in the second order spectrum around 6000 angstroms. This UV continuum is superimposed on the first order spectrum. Based on this paper, I suspect that the peak at 6300 angstroms is [O I].
http://articles.adsa...8;filetype=.pdf

Here is a pretty fascinating 3D model
http://iopscience.io...49/226/2/15/pdf

[robin_astro]

You don’t see these in your first order spectrum, but they appear at twice their wavelength in the second order spectrum around 6000 angstroms. 

It is true that the UV wavelengths at 3000A diffracted into the second order would appear at apparently 6000A  but in practise you cannot see light at this wavelength  in either first or second order spectrum as CCD the camera is not sensitive to this wavelength.  (ie the light in the second order spectrum is not shifted in wavelength, it is the same wavelength, diffracted by twice the angle)

 

Cheers

Robin

[robin_astro]

Although Campbell’s Hydrogen Star is one tenth the mass of WR140, it has a similar spectrum and is classified [WC 9].
 

There is something odd here.  Although SIMBAD does indeed list HD184738 as WC9, The spectrum does not look like WR140 at all. see Christian buil's spectrum of WR140 here for example

 http://www.astrosurf...tars.html#WR140

Campbell's Hydrogen Star is a compact planetary nebula so I suspect we are seeing the combined spectrum of the WR star surrounded by a hydrogen rich nebulosity, the emission from which dominates the spectrum

 

Cheers

Robin

[robin_astro]

There is an interesting  note from 1898 on the appearance of this object in a slit spectrograph, confirming that the Hydrogen  emission comes from a region around the star

http://adsabs.harvar...ApJ.....8..113K

 

Robin

Edited by robin_astro, 08 October 2018 - 08:35 AM.

[brownrb1]

Hi Robin-Thanks for your input and responses to my spectroscopy posts. I don't know of anyone in my area (northern New Mexico) that does any spectroscopy and I appreciate you and others that post here on that subject.

Dick

[robin_astro]

Hi Dick,

 

Are you anywhere near Mayhill by any chance?  (As a Brit, my knowledge of the geography of New Mexico is effectively nil) That is where Ken Hudson, a keen amateur spectroscopist lives. I met him in person this year when he came over here for a joint BAA/AAVSO conference. He is running a spectroscopy workshop next February and some of Europe's top amateur spectroscopists are coming over

 

http://www.smswweb.com/

 

Cheers

Robin

Edited by robin_astro, 08 October 2018 - 03:48 PM.

[brownrb1]

Hi,

By the way I got to checking, in reference to the spectrum of Campbell's Hydrogen Star, there is an ~6300 A emission of  un-ionized [O l] electronic transition ( acually 2 very close together)-not an [O ll] emission.

Dick