AAVSO Alert Notice 657 announces a campaign on HerbigAeBe stars being observed with Chandra in the coming ~10 days. Please see the notice for details and observing instructions.
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
yesterady I took medium-resolution spectra of v1307 Ori and v1410 Ori. I'm not sure if they will be useful or not because the resolution does not match the required R=6000, but they are close. Where can I send the fits?
I have also taken a spectrum of V1410 Ori R=5100 so a little below the suggested. It is very near the moon making imaging challenging.
Contact me directly for the fit file.
Good question, Bill - thanks. The latest Chandra short-term observation list was released yesterday, and one of the HerbigAeBe stars has a revised observation date. V1307 Ori will be observed on November 29, so please keep those observations coming! V346 Ori will be observed on November 28 as originally announced.
Many thanks, and Good observing,
Dear optical observers,
thank so so much for sending me spectra. I wanted to update you where we
are in the Chandra data taking and let you know what the next steps for
this project are.
Three of the five stars in our Chandra program were already successfully
observed (V346 Ori split over two Chandra orbits on 2018-11-25 and
2018-12-28; HD 250550 = V1307 Ori on 2018-11-29; HD 190073 = V1295 Aql
on 2018-12-01). The remaining two are scheduled just around Christmas
(the week starting 2018-12-17).
Thanks to you, we now have optical spectra from all of them. I you get a
chance to observe the remaining two again close to the Chandra
observation, that would be great, but even if not, the spectra you
already send me are very valuable.
We know that the accretion rate in HAeBe stars changes all the time, but
the range seen within a day or within a few days is typically small; on
the other hand, the rate today might be significantly different from
what is was in e.g. 2015. That's why we asked for your help to get a
spectrum within a week or so of the Chandra observation. We can estimate
this rate from the equivalent width of Halpha and I had planned to send
you the numbers I get from your spectra as soon as I have them. It's not
hard to calculate, but I'm going on vacation in a few days and there are
several other things I need to get done before I go (both in astronomy
and in private live, e.g. last week the hot water heater in my home
broke and getting that fixed seemed more urgent to me than calculating
the mass accretion rate of V346 Ori).
I have not yet seen the X-ray data, but we typically wait until all
stars of the program are observed before we really get into the details.
Christian Schneider is the principal investigator
for the Chandra observing program. We'll talk about the results when all
the data is in.
As I said above, it would be great if you get a chance to take a
spectrum of the yet to be observed stars close to Chandra's date. Since
I'll be on vacation, I don't know if I get a chance to post the dates here, but you can always check the Chandra schedule of the
next two weeks here: http://asc.harvard.edu/target_lists/stscheds/index.html
or search for a specific target in this form:
https://cda.harvard.edu/chaser/ (put in "target name", then click
"resolve target", then "search: on the top left).
As for the optical data, when I return from my Christmas vacation, I
will plot and compare all the spectra you send me, get the H alpha
equivalent width, correct that number for the equivalent width that a
non-accretion star for the same spectral type would have, and estimate
the mass accretion rate. For those stars, where I have more than one
spectrum from you, I'll check how much variability there is. Once Christian has had a
chance to look at the X-ray data, and any optical photometry we will
start to compare these stars to other previously observed objects and
see if accretion changes the X-ray emission from Herbige AeBe stars
(that's the goal of this campaign).
Again, thanks a lot for you help. Without you it would have been
difficult for us to learn about the state of the accretion at (almost)
the same time that we look at the X-ray emission with Chandra.