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HD23478-A Type B Rigidly Rotating Magnetosphere

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#1 brownrb1

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Posted 16 February 2024 - 02:30 PM

This is the spectrum that I captured of HD23478- a type B, Rigidly Rotating Magnetosphere(RRM) star. I used an Alpy 600, a 6" Celestron SCT and used Demetra to do the data reduction.  A RRM star's gas is trapped by a strong magnetic field and is forced to rotate at the same speed as the star's surface. RRM's are quite rare, maybe less than a dozen known. This type B3 lV star is dominaed by "chemically pecular" (He l strong) spectra. Even at this low resolution the double peaked H-alpha  emission horns can be seen. Attached is the H-alpha spectrum of HD23478 obtained by an AAVSO member using a Lhires lll high resolution spectrograph

Thanks

Dick

Attached Thumbnails

  • HD23478_ 2024-02-14 224343_JPEG.jpg
  • HD23478_AAVSO_JPEG.jpg

Edited by brownrb1, 16 February 2024 - 03:01 PM.

  • robin_astro, Jim Waters and Ljubo like this

#2 dhferguson

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Posted 16 February 2024 - 02:59 PM

Cheers,

 

Yes, He I absorption lines of 4026A, 4471A, 4921A, and 5876A are also visible in the upper spectrum. He I 5015A is not immediately apparent. I'm not sure what the "line" around 4390A is. However, it points to a possible inverse P-Cygni profile or perhaps a calibration error.

 

Happy observing always,

 

Don



#3 robin_astro

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Posted 16 February 2024 - 07:28 PM

 I'm not sure what the "line" around 4390A is. However, it points to a possible inverse P-Cygni profile or perhaps a calibration error.

 

 

That line appears to be real. It can be seen for example in the ESPaDOnS spectra from the archive

https://www.cadc-ccd....gc.ca/en/cfht/

as used in this paper.

https://ui.adsabs.ha....1928S/abstract

 

 

Cheers

Robin

 

HD23478_ESPaDONS.png


Edited by robin_astro, 16 February 2024 - 07:54 PM.


#4 robin_astro

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Posted 16 February 2024 - 07:36 PM

That line appears to be real. It can be seen for example in the ESPaDOnS spectra from the archive as used in this paper.

 

https://ui.adsabs.ha....1928S/abstract

 

 

Cheers

Robin

 

attachicon.gif HD23478_ESPaDONS.png

He I 4387.93



#5 dhferguson

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Posted 16 February 2024 - 08:30 PM

Cheers,

 

Yes, I considered He I 4387. It should be slightly weaker than He I 4921, which is a higher angular momentum singlet recombination transition. However, optical depths could alter the as-viewed relative recombination strengths. That is why I don't quite consider the 4387 I.D. definitive, although it is probable.

 

Happy observing always,

 

Don



#6 dhferguson

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Posted 17 February 2024 - 11:45 PM

Cheers,

 

FYI: https://ui.adsabs.ha....1928S/abstract

 

In addition to all the above, it would also appear we have some Zeeman broadening due to high magnetic fields in the shell, 'not sure how much.

 

Best,

 

Don




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