Call for monitoring of Be/X-ray binary X Per

Call for monitoring of Be/X-ray binary X Per

Postby Robin Leadbeater » Wed Sep 19, 2018 2:18 pm

I have received via the BAA a request for spectra of X Per from Dr Paul Roche, Cardiff University. X Per is an X-ray binary where material from a Be star disc accretes onto a companion neutron star. It is Vmag 6.7 so bright enough for high resolution spectra.

It is not in BeSS currently as it is not considered a "classical" Be star system but if anyone currently monitoring Be stars could add it to their list he would be grateful. He is looking initially for high resolution H alpha spectra to monitor the state of the disc. Spectra can be added to the BAA or ARAS databases and any changes in disc state seen should be announced here and direct to Paul or me.

More information from him below

Thanks
Robin


He writes:-

I'd like to (re)start a monitoring programme on the Be star X Persei, the optical counterpart to the X-ray pulsar system 4U0352+309. This is an unusual X-ray system, with a slow pulsar (~14 mins spin period) in a wide binary (~250 day) orbit, which exhibits phases where the Be star loses it's circumstellar disc (characterised by unusally faint periods where the primary fades to V~6.9-7.0). X Per is generally a bright B0e star (V~6.4-6.7), and I'm interested in setting up a long term monitoring project to try and follow the system through it's next disc-loss phase.

I did this in the 1990s (as part of my PhD) and it was very successful, and with the growth of amateur spectroscopy I'm keen to see if we can keep tabs on the behaviour of the H alpha line as well as on the photometric behaviour, as this line is a strong indicator of the state of the circumstellar disc that gives the Be star it's "e".

In BeXRB systems (and X Per in particular) the H alpha emission and IR excess are exactly as would be expected from a standard Be star, and the neutron star accretes from passage through the outer regions of the disc (leading to transient emission), so a system like X Per can be considered and monitored in exactly the same way as a single Be star. Changes in the disc have an impact on the X-ray behaviour of the system, as the neutron star is influenced by changes in the size and density of the disc (which is where it occasionally accretes, once the disc reaches the distances of the neutron star orbit). So monitoring the disc emission provides a clue as to the future behaviour of the X- ray source, and I'm hoping that a monitoring programme can help predict X-ray emission when we start to see signs of disc growth and then loss.

Ideally I'm looking for as much UBVRI photometry as possible over the next few years, with any H alpha spectroscopy an added bonus. The system has long period variability, but short period (minutes) changes in both photometry and spectroscopy have been noted previously. I'm going to be setting up a monitoring programme using the Faulkes Telescope Project (via the Las Cumbres Observatory facilities, mainly the 0.4m 'scopes in the network as this is a bit bright for a 2m!), but having additional data would be fantastic and would be really valuable in helping to monitor the overall system on timescales of weeks-months-years, and correlate with X-ray behaviour in particular.

H alpha line profile and the overall spectral shape, and/or just the EW of H alpha, would be useful - H alpha (as high res as possible) is really what I'm after at this point as it's usually the best indicator of disc behaviour, but any data that can be gathered would be great. I'm hoping to get a Masters student to look into all of this over the next year, and then each year after that, as it seems to be an unusual system even amongst the Be stars, and also amongst the BE/X-ray systems!

Dr. Paul Roche
Cardiff University
Faulkes Telescope Project
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Robin Leadbeater » Sat Sep 22, 2018 5:01 pm

This is what the H alpha line looked like last night 2018-09-21 (LHIRES 2400, R~15000)

Robin

X_Per_20180922_THO.png
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Robin Leadbeater » Sat Sep 29, 2018 1:36 pm

Evolution of H alpha over 6 days

xper_20180921-28_Leadbeater.png
xper_20180921-28_Leadbeater.png (23.38 KiB) Viewed 1325 times


He I 6680 line (approximately 15x weaker)

xper_He6680_20180927_945_Leadbeater.png
xper_He6680_20180927_945_Leadbeater.png (17.01 KiB) Viewed 1325 times


RV of both lines in system reference frame

_xper_20180922_965_leadbeater_Ha_He_RV.png
_xper_20180922_965_leadbeater_Ha_He_RV.png (14.11 KiB) Viewed 1325 times



Robin
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Olivier GARDE » Sun Sep 30, 2018 2:50 pm

Last night, I took a spectrum of this star with my eShel spectrograph

The Balmer's lines
Image


HeI 5876

Image
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Robin Leadbeater » Mon Oct 01, 2018 11:09 am

That's great Olivier ! Can you post it to the BAA and/or ARAS databse ?

Thanks
Robin

EDIT: I see it is already in the BAA database. Thanks!
https://britastro.org/specdb/data_graph ... d_pos=none
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Re: Call for monitoring of Be/X-ray binary X Per

Postby etienne bertrand » Thu Oct 11, 2018 3:55 pm

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Re: Call for monitoring of Be/X-ray binary X Per

Postby etienne bertrand » Fri Oct 12, 2018 10:06 am

Le spectre d' X Per ont l'envoie à quelqu'un pour la campagne d'observation ?
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Olivier GARDE » Sat Oct 13, 2018 11:14 am

Etienne,

Tu peut le déposer à la fois dans la database ARAS et la BAA
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
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Re: Call for monitoring of Be/X-ray binary X Per

Postby Robin Leadbeater » Sun Oct 14, 2018 11:16 am

Thanks Etienne !

You are welcome to add your spectrum to the others in the BAA Spectroscopy Database. (You do not have to be a BAA member)
https://britastro.org/specdb/
It uses the BeSS standard and the conditions for use are similar to those in ARAS. The BAA have been collecting and storing variable star data since 1840 so it should be a good place to preserve the data for the future.

Cheers
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: Call for monitoring of Be/X-ray binary X Per

Postby umberto sollecchia » Sun Oct 14, 2018 7:10 pm

Bonsoir à tous, voici ma contribution. Umberto

xper_20181013_874_Umberto Sollecchia.png
xper_20181013_874_Umberto Sollecchia.png (29.32 KiB) Viewed 979 times



Vitesse radiale
xper_20181013_874_VR_Umberto Sollecchia.png
xper_20181013_874_VR_Umberto Sollecchia.png (14.88 KiB) Viewed 979 times
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