Betelgeuse

Re: Betelgeuse

Postby Christophe Boussin » Tue Jan 21, 2020 5:45 pm

Hello all,

After a long period of cloudy nights, here is my contribution to the monitoring of Betelgeuse with two spectra.

The first one was obtained on December 29th, 2019 at 00 h 02 TU (Alpy 600, resolution 503, JJ = 2458847.502, 6 exposures of 10 s) :

_betelgeuse_20191230_002_Christophe Boussin_3700_7570.png
Betelgeuse on December 29th, 2019
_betelgeuse_20191230_002_Christophe Boussin_3700_7570.png (97.85 KiB) Viewed 2752 times


The second spectrum below was obtained on January 20th, 2020 at 20 h 49 TU (Alpy 600, resolution 501, JJ = 2458869.3675, 15 exposures of 20 s) :

_betelgeuse_20200120_868_Christophe Boussin_3700_7570.png
Betelgeuse on January 20th, 2020
_betelgeuse_20200120_868_Christophe Boussin_3700_7570.png (95.4 KiB) Viewed 2752 times


Comparison of the spectra :

BETELGEUSE_Christophe Boussin.png
BETELGEUSE on December 29th, 2019 and January 20th, 2020 (identification of some lines from PlotSpectra)


Since December 29, I have not noticed any significant changes in the spectrum of Betelgeuse except maybe in the red part of the spectrum ?

Clear skies,

Christophe BOUSSIN
CBO (Newton 200 F/5 / Alpy600 / Atik 314L+ / Atik Titan) @ ARAS database
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Re: Betelgeuse

Postby Robin Leadbeater » Wed Jan 22, 2020 1:28 pm

Hi Christophe,

My spectra also confirm the change you are seeing. There has been a continuing increase in the IR compared with the visible region this year (This is consistent with the decrease in V magnitude compared the H,J magnitudes in the AAVSO data)

Cheers
Robin

betelgeuse_20191230_949_Leadbeater.png
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LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
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Re: Betelgeuse

Postby Christophe Boussin » Thu Jan 23, 2020 10:59 pm

Hi Robin,

Glad to read your confirmation of this change !
I am always impressed by the fact that we are able to highlight the same changes from spectra obtained under different conditions : a good illustration of the effectiveness of the process of reduction of our data !

For the record, a recent astronomical telegram (ATel 13410) mentions this decrease in Betelgeuse's brightness and the hypotheses envisaged to explain it :

http://www.astronomerstelegram.org/?read=13410

Clear skies,

Christophe
CBO (Newton 200 F/5 / Alpy600 / Atik 314L+ / Atik Titan) @ ARAS database
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Re: Betelgeuse

Postby James Foster » Fri Jan 24, 2020 12:41 am

Here is my Betelgeuse spectra from 22 & 23 January 2020, shot with the Alpy600(22Jan20) and the LISA-IR(23Jan20):
Image
All identified spectral lines are tentative. Lots of energy being pumped-out of this star in the IR!

James
James Foster
eShel2
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope,
LISA IR/Visual Spectroscope (IR Configured Presently)
Alpy 600 with Guide/Calibration modules and Photometric slit
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Re: Betelgeuse

Postby Firefly » Fri Jan 31, 2020 1:45 pm

Hi all:

Here is my try with 1200L grating tonight. From 6450----6786.
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Re: Betelgeuse

Postby Paolo Berardi » Sun Feb 02, 2020 5:37 pm

Hi Dongdong, hi all!

It looks like Betelgeuse has reached the plateau (but we'll see), so I decided to catch an evidence of the historic minimum too. Spectroscopic observations were carried out on 23/01/2020 with Lhires III and 600 l/mm grating. The profiles cover the wavelength range from about 4200A to 9400A in six spectral intervals picked up in sequence. Spectra above 7000A are obtained with a blocking filter (Wratten 25) in the optical path to avoid the 2nd order contamination.

Image

The combined profile and an attempt to remove the atmospheric absorption bands in the interval from 620 to 940 nm. I derived the bands profile from the spectrum of Bellatrix (reference, B2V) observed with the same setup while it was at similar height on the horizon (the same night).

Image

Comparison with alf Ori Miles spectrum (V mag in the range ~0.4-0.6 in 2000-2001 years). Differences are obvious but it should understand if the the response curve calculation, using Bellatrix spectrum and a couple of Pickles library profiles, is precise enough (I have a little experience with NIR spectra).

Image

Finally, a visual comparison. In 2014 I took a picture of Orion constellation with a DSLR out of focus to emphasise the color of the stars. From AAVSO light curve, Betelgeuse magnitude was about V 0.5 at the time. On january 23th 2020 I repeated the photo shoot. The comparison shows quite well the extreme dimming of the red supergiant.

Image

Paolo
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Re: Betelgeuse

Postby Robin Leadbeater » Mon Feb 03, 2020 12:20 am

Hi Paolo,

Can you try dividing your spectrum by the MILES spectrum to compare with my comparison using the ALPY from 20191230 ?
viewtopic.php?f=38&t=2433#p13514

Thanks
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: Betelgeuse

Postby James Foster » Mon Feb 03, 2020 5:37 pm

To: Paolo

RE:"The profiles cover the wavelength range from about 4200A to 9400A..."
I didn't know you could go so far in the IR with the LhiresIII....did you use an red filter to reject 2nd order spectrum?
I'll post my latest LISA IR/Alpy600 stitched spectrum latter today,

James
James Foster
eShel2
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope,
LISA IR/Visual Spectroscope (IR Configured Presently)
Alpy 600 with Guide/Calibration modules and Photometric slit
Star Analyzer 200
James Foster
 
Posts: 396
Joined: Sun Jan 24, 2016 7:14 am

Re: Betelgeuse

Postby Paolo Berardi » Mon Feb 03, 2020 6:44 pm

Hi Robin, here's the comparison.

Image

I didn't know you could go so far in the IR with the LhiresIII....did you use an red filter to reject 2nd order spectrum?


Yes James. As I said, I used a red filter Wratten 25 to avoid the 2nd order contamination from about 7000A. The grating efficience is not optimized for NIR but luckily the target is very bright!

Paolo
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Re: Betelgeuse

Postby James Foster » Tue Feb 04, 2020 6:52 pm

Here is my most recently processed Alpha Orion spectra for 01Feb20 (visual) & 02Feb20 (IR):
Image
All bands except the UV CaII and Telluric O2 are speculative......thanks Paolo for the info on using the Wratten 25
red filter to avoid the 2nd order long-ward of 7000A using the LhiresIII!

James

p.s. Just byway of comparison, here is a near UV to IR spectrum of Rigel:
Image
James Foster
eShel2
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope,
LISA IR/Visual Spectroscope (IR Configured Presently)
Alpy 600 with Guide/Calibration modules and Photometric slit
Star Analyzer 200
James Foster
 
Posts: 396
Joined: Sun Jan 24, 2016 7:14 am

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