Achernar in emission

Information about outbursts of eruptive stars, Be activity, ...
Post Reply
Malcolm Locke
Posts: 25
Joined: Mon Dec 16, 2013 11:27 am

Achernar in emission

Post by Malcolm Locke »

Hi folks,

I took my first Be spectrum last night, and my first spectrum at 1800 l/mm. Was intended as a test more than anything, but I appear to have caught Achernar (Alpha Eri) in emission.

I am not sure if this is news. The last spectrum in BeSS is from 2011/10/18 and shows no emission.

R ~ 7500. 0.4m SCT, L200 @ 1800 l/mm, SBIG ST8. 8 x 90s. Processed in IRAF.

I do not yet have a BeSS account, I will set that up later today and submit the fits there for appraisal.

Attached is the H alpha line plotted in velocity units, and a comparison with Bernard Heathcote's 2011 BeSS spectrum.
Attachments
achernar_comp.png
achernar_halpha_vel.png
Tasso Napoleao
Posts: 21
Joined: Wed Dec 11, 2013 5:47 pm
Location: São Paulo, Brazil

Re: Achernar in emission

Post by Tasso Napoleao »

Hi friends,

I have already answered to Malc about this in the SASER list. Achernar is actually showing a strong Ha emission, as shown in Malc´s excellent profile. However, we believe this is not news and that the current phase has started sometime around Jan 2013. Through all the second half of 2012, the star was showing the normal B phase, with Ha in absorption (Pls see the attached file "121022 Achernar". From Jan 2013 onwards, however, that pattern started to show a clear change to emission, as it can be seen in the attachments below ("130122", "130702", "130822" and "131020"). All of these are jpegs from the line profiles of Achernar obtained by Rogerio Marcon and myself in the course of our Be patrol during last year. (Newtonian 315mm, homemade spectroscope by Marcon, 2400 l/mm, Audine KAF1602; the first image has poorer resolution because at that time we were using a wider slit).

This series indicated clearly that a circumstellar disk was being formed again around the star. By mid-first half of 2013, we communicated that possible change to Dr. Alex Carciofi, a well-known specialist in Be stars modelling who works at the University of São Paulo (Instituto Astronomico e Geofisico). He soon contacted his peers who are also specialists in this star. On this subject, please see the last paragraph of item 4 in the A&A "Letter to the Editor" below:

http://www.aanda.org/articles/aa/pdf/20 ... 515-13.pdf

With Achernar´s disk in the initial stage of development, Dr. Carciofi and his peers requested time to the VLTI to study the disk evolution through spectro-interferometry (using the AMBER instrument). Granted, their time request was approved. From what I know, first observations were already completed and I believe their results should be available soon.

I am sorry we did not file our profiles in BeSS database as of yet (we also don´t have a BeSS account). Will try to set the registration procedures so that we can post our fits files soon.

Regards,
Tasso.
121022 Achernar.jpg
121022 Achernar.jpg (36.84 KiB) Viewed 3534 times
130122 Achernar.jpg
130122 Achernar.jpg (50.36 KiB) Viewed 3534 times
130702 Achernar.jpg
130702 Achernar.jpg (49.17 KiB) Viewed 3534 times
130822 Achernar.jpg
130822 Achernar.jpg (50.13 KiB) Viewed 3534 times
131020 Achernar.jpg
131020 Achernar.jpg (46.24 KiB) Viewed 3534 times
Post Reply