Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 11/18/2015 - 18:13
The page especially for the UXOR campaign has now been updated following some great feedback at the Boston meeting. The 'old new' list of 41 (visual) stars has now increased to 115 objects (visual/CCD) with all coordinates given. Several of the EA stars have no determined periods at all, so at the very least if no UXORs are found, we may have provided data for these stars' periods! If you are not au fait with how to observe EA stars, please use the link to the EB section on the updated page. As charts become available for these stars, I will add a column to the DB which will be reflected in the page, so do keep returning for the latest updates.
when I go to the site or click on the link in you message above all I see is a small handful of stars and no coordiantes. The message implies more stars and coordinates. I have a student that might like to pursue some of these stars. If you have a better list please advise how I might obtain it. Thanks.
Those 14 stars are the final list, whittled down from the original longer list. I haven't included the coordinates on this page because it is assumed that users will just go to VSP to find the chart/sequence. Sorry for the 'promises' in the original post!
How correctly to make observations for these stars in order to distinguish them from the Algoles? I was very interested in this topic.
Thank you.
Catching en eclipse will in some cases be enough to at least classify them properly.
An EA-type eclipse will show a symmetry (clean and similar descending and ascending branches) that won't be present in an UXOR light curve.
Check VSX to see the last information on any star you observe (we constantly update information so it might be that some stars are already confirmed as EAs and have periods).
When you observe enough filter V? Because the main indicator is the non-symmetry in eclipses.
Multicolor data are always useful.
These stars have B-V bluer than J-K so determining B-V for those who lack it will be revealing.
Also the fact that at deep minimum they undergo a color reversal: they get redder as they fade but then start to get bluer again.
But the symmetry of the fadings will be one of the best indicators.
Cheers,
Sebastian
It turns out that out of eclipses B-V is darker than J-K?
No, the opposite and that is one of the ways to find them. They show infrared excess and B-V is bluer than J-K.
To avoid confusion I wouldn't call the fading events "eclipses" although the star is dimmed by dust/gas clumps.
Once again I will ask, because a very important point. Outside of eclipses, the star is blue, and when it eclipses, it turns red? Do I understand correctly?
The star is not necessarily "blue", it is bluer in B-V than in J-K.
These are mostly B and A-type stars (Herbig AeBe stars) although the UXOR behaviour has been recently found in later types too.
There is some reddening in B and V too so you won't find UXORs with negative B-V even among the B-type stars.
And again, don't call them eclipses.
These stars get redder when they start fading but as the fading gets deeper this behaviour changes and they become bluer again. It would be interesting to see this in the data.
Thank you. I will try to discover these changes.
- What does "infrared excess" mean? In what cases can infrared radiation be considered redundant?
- What processes are caused by blue during the low minimum?
Thank you.
All heat sources (including non-'red' stars) emit Infra-red, but usually in the case of stars, this IR is overwhelmed by the shorter-wavelength emission. The IR is still there, it is just 'swamped' by the rest of the radiation.
With many YSOs, the presence of the circumstellar dust/gas cloud - which is warm enough to emit IR but not, as a rule, visible light because of its comparatively low temperature - allows there to be comparatively more IR radiation than with main-sequence stars, and this is the IR excess.
Hi,
is there interest in a denser coverage of those stars? I could cover the latter 7 from my remote observatory in snapshot mode. I could do B and V images.
Is there anybody interested in the results and will do the analysis/paper writing?
Josch
I was interested in these stars and I began to observe them. Now I am accumulating material. In parallel, I develop a methodology for observations. If there is any data, it will be good.
I have not yet started observations, but will take up some stars and send data to the AAVSO.
I will use a V filter to start with. If you are interested in more filtered data I could also use B and I filters.
Josch
As I understand it is necessary to determine the beginning of the eclipse and then check the color indicator "B-V". But in the normal state, too, several observations are needed through the filter "B" for comparison.
B and V would be useful to see the color reversal at minimum.
You can go multicolor as soon as you detect a fading (a couple of BV points at maximum would also be useful for comparison as Nikolay said).
Ok, after I got my first images tonight to see the exposures in V I will add B exposures as well.
I am doing the stars in Sco and the one in Sct.
Josch
Good. Just this area of the sky is not accessible to me. I'm now testing Cyg, Cas and Lac.
In addition to what Sebastian says about 'eclipses', another point to note is the lack of strict periodicity, and also behaviour outside of 'eclipse'.
HI,
first data points are uploaded to the AAVSO databse for the 4 stars.
More to come.
Josch
Can you write what?
I have uploaded V data on the three stars in Sco and the one in Sct. My initials are HMB. I have not had the time yet to add B filter to my observing program, which is very intense (Observing more than 45 stars nightly). Do you need more information?
Josch
Yes, if it is possible, which stars did you observe? And filter "B" is desirable to use together with "V". For example, "B-V-B-V". At least one observation is so to conduct, well, if you notice the darkening, it is surely in this order.
Nicholay.
I checked the website of the 14 remaining stars
Those are the ones I observe:
V0603 Sco
13.2
13.8
26.3
V0698 Sco
12.7
13.7
258
V0699 Sco
13.4
14.7
0
V0730 Sco
13.8
14.3
0
HI Sct
15.4
16
0
Who has the opportunity to observe today in the interval between 19.30 and 21.00 (UT) OU Cas. We need a continuous photometric series of B-V-B-V.
The "OU Cas" is of type EA.
HI after nearly one month of daily snapshits the B-V of HI Sct is about 2, for V603 Sco about 1.3, for V698 Sco about 0.5, for V699 Sco about 1.2. V730 Sco I have not started yet. For V603 Sco I got already a minimum.
Josch