Campaign of b Persei...

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Campaign of b Persei...

Postby Francisco Campos » Fri Jan 26, 2018 7:54 pm

(don't confuse with Algol).

Hello,

a new campaign of b Per has been announced in the AAVSO Alert campaign. This is an elliptical variable but also an eclipsing one. There is a third component that orbits the two main stars every 704.5 days and eclipses the system producing a very interesting photometric curve. Due to this peculiar dance, we can observe a very complex eclipse but there are other interesting phenomena more difficult to explain.

The eclipses last more than two days and a worldwide coverage is needed. In this campaing, spectroscopy will be also appreciated.

I don't have more details about what is requested in spectroscopy, but considering that b Per is bright (4.6m at maximum), I think it will be a nice target for Lhires, Mussol's and eshel spectrographs.

I will follow photometrically again b Per during the next weeks. In fact, the planning schedule is an intense coverage from Feb. 5 to Feb. 19, 2018.

More details about this campaign here:

https://www.aavso.org/aavso-alert-notice-610

Greetings,
Fran
Francisco Campos
 
Posts: 85
Joined: Sun Nov 29, 2015 10:13 pm

Re: Campaign of b Persei...

Postby Peter Somogyi » Tue Jan 30, 2018 6:31 pm

Thank you Francisco for the alert, was reading around for a while - just was unsure to get any usable weather till the event!
Yesterday I've had partially cloudy sky with veils, but fortunately the target was also bright enough!
After several experiments (initially targeted H-gamma + CaI 4227- where have had flat problems), returned to the CaII H/K region where already have some practice:
bPer.png

This one is 18 x 5 minute (23 micron slit, 2400/mm grating, R~6000 average, speculated of a serie - a 5 x 5 min could be already enough), and the total sum got absolutely noiseless. Also returned to this object multiple times within a total of 5 hours interval (clouds in between) trying to catch any variability, but finally couldn't detect anything above noise (was expecting at least some RV change from the 1.5 day period).
On the graph, I've taken features from "1976, THE RADIO-FLARING TRIPLE SYSTEM b PERSEI (Graham Hill, G. C. L. Aikman, and Anne P. Cowley)".

Conclusion from this graph:
- Balmer has a wide V-shape (+/- 1500 km/s velocities at edge points)
- Ca II 3933 having 150km/s at half width, and the small features (Si II, Ti II, ...) look to be similar

In case anyone takes this region again at a similar resolution, I'd happily look at the differences (no professional hint yet).

Cheers,
Peter
Peter Somogyi
 
Posts: 380
Joined: Sun Jul 13, 2014 8:56 am

Re: Campaign of b Persei...

Postby Francisco Campos » Wed Jan 31, 2018 10:19 pm

Hi, Peter,

thank you for the comments. I took last night a spectrum but my resolution is worse (bad focusing I believe). I see important differences. Look for example at Ti II band (3913 A). In your spectrum is clearly visible but not in the mine.

I'm going to sent this spectrum to the AAVSO. I asked for more information about what they expect from these spectra but I still haven't received reply.

_bper_20180131_793_FPC.png
_bper_20180131_793_FPC.png (9.39 KiB) Viewed 2783 times


Greetings,
Fran
Francisco Campos
 
Posts: 85
Joined: Sun Nov 29, 2015 10:13 pm

Re: Campaign of b Persei...

Postby Peter Somogyi » Mon Feb 05, 2018 1:23 pm

Thank yor the inquiry on the aavso forum Francisco, I can read now we got the professional hint.
Yesterday I've taken a 2nd spectrum (13 x 5 min), and apart form a 5% continuum error (equalised via a low order curve fit division just for an easy comparison), I get only small radial velocity difference now - per components:
bPer_rv.gif
Compare _bper_20180204_764 to _bper_20180129_795.
bPer_rv.gif (45.13 KiB) Viewed 2751 times

Manually testing rv shifts (step: 1 km/s), I'm getting these values per feature (2018.01.29 vs 02.04 yesterday):

H8: -9 km/s (+/- 1 km/s)
H9: -10 km/s (+/- 2 km/s)
CaII 3933: -14 km/s (+/- 0.5 km/s on center)
Ti II 3913: -20 km/s (+/- 5 km/s, noise)
Si II 3856: -15 km/s (+/- 3 km/s)

As for the weak features shifts, for practical reasons I've subtracted a close value to 1 (here chosen 0.7) from both spectra to enlarge the ratio errors.
The rv shift differences after this 1 week period between Balmer (9-10 km/s) and metallic lines (14-20 km/s) is doubtless via testing the shifts via human look.
Hope any of us may catch bigger changes in the next week (not much time left)!
- Peter
Peter Somogyi
 
Posts: 380
Joined: Sun Jul 13, 2014 8:56 am

Re: Campaign of b Persei...

Postby James Foster » Wed Feb 14, 2018 10:44 pm

I've compared velocity corrected H-alpha spectrum of b PER btw the dates of 04 and 14 Feb 2018 and got a 1.8A difference btw them. Note sure how this corresponds
to the velocity components of Star A with Star C being eclipsed (alot of water vapor in the air for the 14Feb18 spectra!):
Image
I'm working on the HB and CaK spectrum I took on various days btw these dates.

James

p.s. I submitted almost 500 RVB photometric observations of this object to AASVO last night......used a 400mm mirror-lens Nikon (67mm aperture with large
central obstruction) attached to an ST-8xe on-top of the telescope (CDK17) I used to take spectra.
James Foster
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: 297
Joined: Sun Jan 24, 2016 7:14 am

Re: Campaign of b Persei...

Postby Peter Somogyi » Thu Feb 15, 2018 5:28 am

Hello James,

Such an RV shift is well expected in b Per in short term.
As an example, here I attach my period-RV diagram of my CaII 3933 and H8 features:
bPer_20180211_state_RVs.png

black: evening of 2017.01.29, 37 x 5 min (clouds in between, but like 6 hours coverage, its end was suffering of athmospheric effects)
red: evening of 2017.02.04, 13 x 5 min (only 1 hour, but the most shift... also perfectly extending the previous serie)
green: evening of 2017.02.11, 46 x 5 min (~ 5 hour by coverage)
(using scripted lamp between each exposures, calibrating the frames individually)

To get the centroid, I've used here a scripted way (IRAF: splot/d feature) to measure the centroid, and still experimenting... For CaII, the profile very much obeys Lorenzian or Voigt type (but definitely not Gauss). For the Balmer V-shape, none of these profiles obey... might be also composite, and unsure why seeing shift (but such a shift between metallic and Balmer also mentioned in the document form 1976)!
The graph itself is helocentric (applied a constant value per session - adds 0.2km/s error, it's my neglection) and average vrad-corrected (by the 19.7km/s value from Simbad).

But as you can already see, the CaII diagram obeys SB9 database's diagram - see:
http://sb9.astro.ulb.ac.be
(direct link should be: http://sb9.astro.ulb.ac.be/Orbits4onesystem.cgi?226 , please scroll down to the graph...)
The CaII is a very dominant and nicely obeying feature, free from A component's contamination, and the 3rd F compaion is weak (should be at 0 km/s as of now, but yet I can't elaborate).

So far, everything is known... (the 80 km/s difference is visually the whole width of CaII 3933 on my raw frames)
Nevertheless, it's my first EB system, and happy to learn it.

I am amateur-personally very interested in your CaII/H8 spectra missing from my serie, preferably in a form of a serie of sub-exposures - you must haven been much luckier than me by catching the critical time! In case you send me, I would be happy to investigate (again, as a non-professional)!
Also suggest that you shoot it again out of the eclipse, maybe it can't perfectly compare with mine (changes must be weak).

By the way, to show up something for the profs, what we finally need is one of these:
- find a signature of the faint 3rd component (I'm still investigating, perhaps need to artifically reconstruct all the components, RV-shifted for each exposure ...)
- any visible spectral change due to eclipse (your spectra is critical here, mine didn't show anything obvious - other than the well expected shifts...)

Cheers,
Peter
Peter Somogyi
 
Posts: 380
Joined: Sun Jul 13, 2014 8:56 am

Re: Campaign of b Persei...

Postby James Foster » Thu Feb 15, 2018 10:47 am

To: Peter,

Thanks for the offer! I have to admit my spectroscopic analytical skills are lacking. The best I've been able to do is heliocentric velocity corrections to the spectra through
Bass V1.98. Here is the CaK region I got for 7 and 14Feb18:

Image

I'll be in the field the next couple of nights, so I'll get you the files later next week.....packing 600lbs of equipment to a 8300ft elevation mountain at the last minute is taxing!

James
James Foster
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: 297
Joined: Sun Jan 24, 2016 7:14 am


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