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

[Robin Leadbeater]

Thanks Umberto ! Can you post the fits file or add it to one of the the databases please

Cheers
Robin

[umberto sollecchia]

Bonsoir Robin, j'ai envoyé le fit à à votre e-mail privé.
Salut
Umberto

[Joan Guarro Flo]

Hi,
Really X Per has a very interesting graphic, but at the moment don't see excessive movement in it.., we're wait to next future.

Regards, Joan.

[Robin Leadbeater]

Superb Joan ! A very impressive correction of the blaze function.

Thanks
Robin

[Peter Somogyi]

Last night's exploration of the CaII - H8 region (R~5500 average, edges defocused a little):

The CaII doublet is very thin, and features weak (despite bright continuum: 3000 ADU).
Asymmetric peak is confirmable on H7 + CaII blend and perhaps H9.
Velocities are generally larger than H-alpha or He I:

Xper_Hzeta.gif (28.43 KiB) Viewed 15428 times

H8 consists of a wide absorption, a central peak and a satellite peak.
Question how it is changing (appreciate to see more spectra by others just to learn, though no professional requested it).
- Peter

[Robin Leadbeater]

The X Per season is open again. We have good continued coverage on at least a weekly
basis up to March this year. (Particular thanks to Joan Guarro Flo.)

There were only small scale variations in the H alpha profile up to March but then the redward component started falling significantly in March and my first measurement post solar conjunction suggests this continued to point that the redward component now no longer dominates the profile (see attached selected line profiles)

xper_Halpha_20180921-20190807.png (29.15 KiB) Viewed 14294 times

Please check the BAA database for updates and consider taking a spectrum if you see the latest spectrum is more than two weeks old

Thanks!
Robin

[Robin Leadbeater]

An update and some feedback from Dr Paul Roche

The EW of the H alpha line has been dropping since the beginning of the year. There has also been a 0.15 drop in V magnitude. (AAVSO data) This might be an indication of disc loss

XPer_Ha_EW_trend-20191113.png (8.81 KiB) Viewed 13800 times

xper_20190108-20191027_Leadbeater.png (37.42 KiB) Viewed 13800 times

xper_20190108_v_20191027_Leadbeater.png (19.15 KiB) Viewed 13800 times

Thanks!

---------------------------------------------------------------------------------

Feedback from Paul Roche 20-11-2019

It certainly looks like behaviour similar to that prior to previous disc-loss events (weakening H alpha, fading V mag). It would be interesting to see if system is becoming bluer as well, as tends to happen when the red circumstellar disc dissipates. I'd be particularly interested in any infrared observations (I band, or even JHK bands - although that's getting very tricky!), as that's another good probe of the extent of the circumstellar disc.

There's nothing much happening in X-rays at the moment as far as I can see, but I'd like to keep an eye on as many wavelengths as possible as we typically see an interaction between the neutron star and the disc material if the disc expands/moves outward and reaches the (wide) NS orbit eventually (assuming the disc material is being expelled outwards from the star... if it "collapses inwards", we won't see any interaction and the NS will continue it's gradual spin-down).

It's hard to predict when the H alpha emission will disappear (if it does...) and the normal B-star absorption becomes visible again, but weekly observations are fine for now. If it appears that the decrease in H alpha EW is accelerating, it would be worth trying to increase cadence to every couple of days to capture those final stages.

[Robin Leadbeater]

There has also been a reduction in the EW of the He 6685 line over the past year but at a faster rate than at H alpha so the He line could go into absorption very soon. I am clouded out and the last observation was on 2020-01-06 so is anyone able to check this star at He 6685 (and H alpha) please ?

Thanks
Robin

XPer_He6685_EW.png (17.58 KiB) Viewed 13213 times

XPer_Halpha_EW.png (15.67 KiB) Viewed 13213 times

[Robin Leadbeater]

There has also been a reduction in the EW of the He 6685 line

Correction, that should read He 6680 line (Actual rest wavelength 6678.15A)

The latest result 2020-01-11 (Thanks Peter !) confirms the continuing trend so an updated spectrum would be useful

Robin

[Robin Leadbeater]

An update before the next season starts:

There are now over 230 spectra in the BAA spectroscopic database. Thanks to all contributors ! Continuing monitoring on a nominal 2 week basis during the next season is requested. The following is just a quick analysis of a selection of the available spectra.

The fall in EW of both the H alpha and He 6680 lines plateaued during January 2020 and remained constant up to the last recorded spectra on 2020-04-06 so there was no complete loss of the disc, though the He line in particular became very weak at just -0.4A EW

X_Per_HA_EW_trend_20200611_annot.png (9.6 KiB) Viewed 11901 times

X_Per_He6680_EW_trend_20200611_annot.png (10.35 KiB) Viewed 11901 times

A snapshot of 5 heliocentric corrected line profiles during the monitoring period (marked A-E on the EW plots) shows the complex evolution of the lines and although the EW was approximately constant from Jan to April 2020, the line shape continued to evolve.

Xper_Ha.png (10.02 KiB) Viewed 11901 times

Xper_He_6680.png (18.45 KiB) Viewed 11901 times

Although noisy due to the weakness of the line, there are significant differences in the He 6680 line profile compared with the H alpha line with higher radial velocity features particularly on the red edge.

Here is the AAVSO Vmag light curve for the same period. There is no obvious correlation

X_Per_AAVSO_v_20200611.png (34.24 KiB) Viewed 11897 times

Cheers
Robin