V442 And Be star in outburst

Information about outbursts of eruptive stars, Be activity, ...

Re: V442 And Be star in outburst

Postby Olivier Thizy » Mon Sep 04, 2017 9:19 am

Hello all,


My call for observation of V442 Andromedae was well received and thanks to several of you, at least one spectrum has been taken every night and most of the time several per night!

So here is as of september 4th the daily Halpha evolution since the outburst discovery on the night of august 21st:

V442 daily evolution aug21-sep3.JPG
V442 daily evolution aug21-sep3.JPG (130.31 KiB) Viewed 5982 times



The changes seem less pronounced for the past three nights but additional observations are required to confirm or not (again, my weather forecast are not great for next few nights). Note that no period has been searched/calculated yet as my focus is on data acquisition so far.

Last but not least spectra should of course be uploaded on BeSS database for further/detailed study.


Let's continue to observe this outburst with as much frequent spectra as possible,

Cordialement,
Olivier
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

Re: V442 And Be star in outburst

Postby Christian Buil » Wed Sep 06, 2017 11:26 pm

A VHIRES-MO spectrum of V442 And taken the 2.9/09/2017 at R=50 000 with a C9.25 telescope, and for the first for me,
by using a CMOS camera (ASI1600MM-C) on an echelle spectrograph. Detail of Halpha line and the full spectrum taken with VHIRES-MO.

Christian B
Attachments
_v442and_20170902_932_25.png
_v442and_20170902_932_25.png (24.86 KiB) Viewed 5957 times
_v442and_20170902_932.png
_v442and_20170902_932.png (86.19 KiB) Viewed 5957 times
Christian Buil
 
Posts: 1332
Joined: Mon Sep 26, 2011 6:59 pm

Re: V442 And Be star in outburst

Postby Olivier Thizy » Sat Sep 09, 2017 4:15 pm

Hello,


V442 And was in a more stable state for the past few days but - thanks to Joan Guarro Flo latest observations - there seems to be again some activity going on. Here are the daily graphs (one selected graph per night). The two graphs at the top are the one from Joan Guarro showing the double peak evolution again:

V442 daily evolution aug21-sep8.png
V442 And daily evolution
V442 daily evolution aug21-sep8.png (80.74 KiB) Viewed 5933 times



Based on Coralie Neiner suggestion, I measured V/R and V+R for all the spectra I have a copy of. I used MatLab with gaussian fit on two spectral domains; I did not model/remove the absorption so I guess this is a first "draft".

The V/R is showing an evolution (periodic? same period as the star around 2.6 days?) for approximately 10 days after the outburst discovery, then a more stable ratio, and now is back to variability again. It looks like the ejected material initially had the star momentum (and rotational period) then as it moved away it moved into a more Keplerian rotational behaviour (and different period); and more recently another ejection of material?

V442And V_R evolution aug21-sep8.png
V/R
V442And V_R evolution aug21-sep8.png (13.35 KiB) Viewed 5933 times



At the same time, V+R is showing a smooth increase then a stabilization for the past few days. This tends to indicte that the V/R variation above are mainly due to material around the star NOT homogeneous:

V442And V-plus-R evolution aug21-sep8.png
V+R
V442And V-plus-R evolution aug21-sep8.png (11.33 KiB) Viewed 5933 times



Bottom line is that this is a very interesting Be star outburst and I encourage you to continue observing it. As usual, upload your spectra on BeSS but please send me a copy so I can update the data/graphs accordingly.

Cordialement,
Olivier Thizy
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

Re: V442 And Be star in outburst

Postby Olivier Thizy » Tue Sep 12, 2017 6:37 am

Hello,


Thanks to Dong Li & Patrick Fosanelli recent observations, there is confirmation of the activity of V442 And after a short "quiet" period with Halpha emission showing variability, V/R variable again while V+R seems to remain more stable:

V442 daily evolution aug21-sep.JPG
V442 daily evolution aug21-sep.JPG (138.95 KiB) Viewed 5892 times


V442And V_R evolution aug21-sep11.JPG
V442And V_R evolution aug21-sep11.JPG (43.07 KiB) Viewed 5892 times


V442And V-plus-R evolution aug21-sep11.JPG
V442And V-plus-R evolution aug21-sep11.JPG (45.97 KiB) Viewed 5892 times



I folded V/R over the 2.615 days period; here is the result:

V442And V_R phased evolution aug21-sep11.JPG
V442And V_R phased evolution aug21-sep11.JPG (40.86 KiB) Viewed 5892 times



Last but not least, I measured He I 6678 center and plotted it against the 2.615 days period:

V442And HeI6678 phased evolution aug21-sep11.JPG
V442And HeI6678 phased evolution aug21-sep11.JPG (37.46 KiB) Viewed 5892 times



Cordialement,
Olivier
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

Re: V442 And Be star in outburst

Postby Olivier GARDE » Wed Sep 13, 2017 9:49 am

evolution of V442 And in 5 days
Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
Olivier GARDE
 
Posts: 1049
Joined: Thu Sep 29, 2011 6:35 am
Location: Rhône Alpes FRANCE

Re: V442 And Be star in outburst

Postby Olivier Thizy » Sat Sep 16, 2017 7:32 am

Hello all,


Here is a quick status on V442 Andromedae Be star outburst since august 21st. The V+R graph is now showing a clear decrease:

V442And V-plus-R evolution aug21-sep15.JPG
V442And V-plus-R evolution aug21-sep15.JPG (31.38 KiB) Viewed 5852 times



The V/R graph is showing some variability but slower than the 2.6 days periodic variations that were clearly visible at the beginning of this emission phase:

V442And V_R evolution aug21-sep15.JPG
V442And V_R evolution aug21-sep15.JPG (31.93 KiB) Viewed 5852 times



Here are the data folded over the 2.6 days (star rotation) period:

V442And V_R phased evolution aug21-sep15.JPG
V442And V_R phased evolution aug21-sep15.JPG (31.56 KiB) Viewed 5852 times



Here is the updated daily specra graph:

V442 daily evolution aug21-sep15.JPG
V442 daily evolution aug21-sep15.JPG (150.23 KiB) Viewed 5852 times



Last but not least, I looked into BeSS archive were several emission phase have been recorded. I tried this view with a down arrow when no emission and a up arrow when emission is visible with size depending on the intensity of the line(s). From this graph, it looks like active (emission) phase last between 3 to 6 months while quiescence (no emission) phase last between 6 to ~21 months:

V442And_BeSS-history.png
V442And_BeSS-history.png (34.87 KiB) Viewed 5852 times


This type of graph shows the importance of the BeSS Be star monitoring that started about ten days ago. Long term monitoring is giving us some statistics on the outburst events. And current short term regular monitoring - thanks to all the active observers involved with V442 And current outburst follow up - is giving some details on the outburst mechanism...


And for the fun, I have been working on remote observation. I observed last night from home... with fireplace heat and Star Trek Voyager serie on TV! :-)

Remote_obs.jpg
Remote_obs.jpg (61.77 KiB) Viewed 5850 times



Hre is a capture of last night observing session where the spectrum signal has been increasing as the target as rising up in the sly (and I suspect the sky transparency was getting better too):

Capture Acquisition V442 And.JPG



Keep observing V442 And - and clear skies to all,

Cordialement,
Olivier
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

Re: V442 And Be star in outburst

Postby Christian Buil » Mon Sep 18, 2017 4:12 pm

V442 And spectrum taken the 12.939/09/2017 by using a modified VHIRES-MO (ASI1600MM-C detector):

Image

Christian
Christian Buil
 
Posts: 1332
Joined: Mon Sep 26, 2011 6:59 pm

V442 And Be star outburst - 30 days after

Postby Olivier Thizy » Thu Sep 21, 2017 5:39 am

Hello,


V442 And is still very active, 30 days after the discovery of its outburst. There is a strong interest from Noël Richardson (university of Toledo) for our data. They have done some observation of their own and he is encouraging us to continue observing: "this seems like a rare opportunity to trace the mechanisms of how small ejections in Be stars operate to build a disk. Please keep observing!"


Here is the V/R graph showing variations. Note also a very good time coverage during last two days with Dong Li & I.

V442And V_R evolution aug21-sep20.JPG
V442And V_R evolution aug21-sep20.JPG (34.05 KiB) Viewed 5783 times



There are now 95 spectra from 8 observers - any more high resolution (R>10000) observers to join the "party"?:

Capture.JPG
Capture.JPG (27.19 KiB) Viewed 5783 times



The V+R continues its decrease and it would be very interesting to see the future evolution:

V442And V-plus-R evolution aug21-sep20.JPG
V442And V-plus-R evolution aug21-sep20.JPG (33.31 KiB) Viewed 5783 times



And here is the updated daily graph evolution:

V442 daily evolution aug21-sep20.JPG
V442 daily evolution aug21-sep20.JPG (163.88 KiB) Viewed 5783 times



In summary: outburs is still in progress and Halpha emission line(s) continues to evolve over time. So it is a good time to observe, specially with R>10000 spectrographs. If you would like to observe, just follow BeSS procedure & standards, upload your spectra on the database and please send me a copy so I can update the graph with your data...

BeSS: http://basebe.obspm.fr/basebe/


Cordialement,
Olivier
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

Re: V442 And Be star in outburst

Postby Olivier GARDE » Wed Sep 27, 2017 11:50 am

Last change in V442 And spectrum
Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
Olivier GARDE
 
Posts: 1049
Joined: Thu Sep 29, 2011 6:35 am
Location: Rhône Alpes FRANCE

V442 And Be star in outburst update

Postby Olivier Thizy » Thu Sep 28, 2017 5:52 am

Hello,


128 spectra of V442 And (hd6226) have been collected since the outburst discovery on the night of augst 21st [still waiting for more observers to join in... :-)], for a total exposure time of 135 hours:

V442And Observers.JPG
V442And Observers.JPG (26.14 KiB) Viewed 5695 times



I have a mea culpa to make - I did a mistake in the V & R calculation. Basically, I wanted to remove 0.9 on each measurements in order to compensate for the absorption line (until I find a way to model it); well I added the 0.9 instead. Here are the corrected data. They show very similar information, but more accurately! :-)

The emission increased but is now in the decline as the V+R graph shows:

V442And V-plus-R evolution aug21-sep27.png
V442And V-plus-R evolution aug21-sep27.png (14.79 KiB) Viewed 5695 times



The V/R is still showing variability. I grouped in blue the variable phases, in green the more stable ones:

V442And V_R evolution aug21-sep27.png
V442And V_R evolution aug21-sep27.png (23.72 KiB) Viewed 5695 times


A period analysis shows a period of 2.6852 days:

V442And V_R phased evolution aug21-sep27.png
V442And V_R phased evolution aug21-sep27.png (31.69 KiB) Viewed 5695 times


This is very close to the period found on HeI 6678 stellar photospheric line, ie the star rotation itself:

V442And HeI6678 phased evolution aug21-sep27.png
V442And HeI6678 phased evolution aug21-sep27.png (23.96 KiB) Viewed 5695 times



The Halpha daily graph shows the evolution over time:

V442And daily Halpha evolution aug21-sep27.JPG
V442And daily Halpha evolution aug21-sep27.JPG (185.52 KiB) Viewed 5695 times


The Hbeta emission is now almost gone:

V442And daily Hbeta evolution aug21-sep27.JPG
V442And daily Hbeta evolution aug21-sep27.JPG (169.63 KiB) Viewed 5695 times



More study should come out of those observations. This is clearly an excellent opportunity to study such small ejecta outburst. The emission should last for several weeks (couple of months?) so please keep observing. A SNR of 100 is prefered if you can. Of course, spectra should be uploaded in BeSS for archive and future study. Please send a copy to me (thizy@free.fr) so I can add it in this analysis.

Cordialement,
Olivier
Olivier Thizy
 
Posts: 370
Joined: Sat Sep 24, 2011 10:52 am
Location: in the french Alps...

PreviousNext

Return to Outbursts and alerts

Who is online

Users browsing this forum: Google [Bot] and 2 guests

x