Recent Activity
Since the previous issue we have seen a considerable amount of activity among young variable stars. All the recorded examples here are of UXOR-type stars, but since their fades - which typify the group - are easier to spot, this is a selection effect and so you need to follow all YSOs! One of these that is now coming into view is V347 Aur, which is a most interesting object. Although it can be quite faint at minimum it does show semi-periodic 'outbursts' which make it not an UXOR but an EXOR. VY Tau is similar.
However, the three stars that have shown recent fades are:
- CO Ori: our stalwart John Pickett (who now has a new and impressive observing rig) announces a fade of this object. He says it has "been in steep, steady decline for a few weeks now, since I first recovered it last month [September]. I expect it to be at minimum now [Oct 19], and recovering soon."
- MQ Cas: this is one of mine I'm afraid! On October 4th the star was so faint even the faintest comp star then in the sequence (14.1) was 'out of bounds' but had to be used anyway. My estimate was 141-12 making MQ 15.3 - way beyond its official minimum. Observations by ASASSN show similar fades happening in a rough period of about 400 days (not unlike one of my other favourite stars, V1117 Her). I have since extended the sequence to magnitude 16.0 so now nobody has an excuse not to follow it!
- BM And: another probable UXOR. Here, activity is rather more eventful, if not quite so extreme. Late September saw a fade to 14.2 which I believe is the faintest I have seen it. Always worth looking at this one as it is in a rather pretty, bright cluster with a distinctive shape, and in the same field as the more famous star Z And.
- AB Aur: this bright object which underwent a deep fade in mid-September has now recovered and is back at or near maximum around 7th mag, and thus a good target for even amateur spectroscopes.
Excellent historical article
Well, hardly 'historical' - but SFN 307 (July 2018) has an excellent 'perspective' on - to anticipate our next article - bipolar jets. Too long to reproduce here, I can strongly recommend it. |
Baby Star Search
The citizen science organisation Zooniverse announces a new project to find Herbig-Haro (H-H) objects (to save space, if you're not au fait with the term, just google it). The team says "...Baby Star Search team is searching for Herbig-Haro (HH) objects, which are jets of gas produced by newly-forming "protostars". HH objects are important because they show us where new stars are forming. However they are quite rare - only about a thousand of them are known to exist...
To find HH objects researchers are taking pictures of giant nebulae where stars form. The pictures are taken with the Dark Energy Camera (DECam) on the Blanco 4-meter telescope, which is located at the Cerro Tololo Interamerican Observatory in Chile. The images produced by this camera are huge - about 570 megapixels each. To make the search easier, each one of these images is divided into about two thousand smaller ones. There are currently about 50,000 images in total - and we need your help to search them! To join the research project please visit the site."
FUORs again
SFN 307 (see left) contains a really interesting paper by our own Bo Reipurth on a favourite topic of his I know! - FU Orionis stars and similar objects. They use the similarity of the stars' NIR spectra for inclusion in their survey. FUORs represent a stage in the formation of low-mass stars like the Sun. The survey also identifies two new probable members of the group as a result of those NIR properties.
McNeil's nebula with the FUOR V1647 Ori |
