Page 1 of 2

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

PostPosted: Wed Sep 19, 2018 2:18 pm
by Robin Leadbeater
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

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

PostPosted: Sat Sep 22, 2018 5:01 pm
by Robin Leadbeater
This is what the H alpha line looked like last night 2018-09-21 (LHIRES 2400, R~15000)

Robin

X_Per_20180922_THO.png

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

PostPosted: Sat Sep 29, 2018 1:36 pm
by Robin Leadbeater
Evolution of H alpha over 6 days

xper_20180921-28_Leadbeater.png
xper_20180921-28_Leadbeater.png (23.38 KiB) Viewed 2607 times


He I 6680 line (approximately 15x weaker)

xper_He6680_20180927_945_Leadbeater.png
xper_He6680_20180927_945_Leadbeater.png (17.01 KiB) Viewed 2607 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 2607 times



Robin

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

PostPosted: Sun Sep 30, 2018 2:50 pm
by Olivier GARDE
Last night, I took a spectrum of this star with my eShel spectrograph

The Balmer's lines
Image


HeI 5876

Image

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

PostPosted: Mon Oct 01, 2018 11:09 am
by Robin Leadbeater
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

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

PostPosted: Thu Oct 11, 2018 3:55 pm
by etienne bertrand

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

PostPosted: Fri Oct 12, 2018 10:06 am
by etienne bertrand
Le spectre d' X Per ont l'envoie à quelqu'un pour la campagne d'observation ?

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

PostPosted: Sat Oct 13, 2018 11:14 am
by Olivier GARDE
Etienne,

Tu peut le déposer à la fois dans la database ARAS et la BAA

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

PostPosted: Sun Oct 14, 2018 11:16 am
by Robin Leadbeater
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

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

PostPosted: Sun Oct 14, 2018 7:10 pm
by umberto sollecchia
Bonsoir à tous, voici ma contribution. Umberto

xper_20181013_874_Umberto Sollecchia.png
xper_20181013_874_Umberto Sollecchia.png (29.32 KiB) Viewed 2263 times



Vitesse radiale
xper_20181013_874_VR_Umberto Sollecchia.png
xper_20181013_874_VR_Umberto Sollecchia.png (14.88 KiB) Viewed 2263 times