[vsnet-alert 12371] FWD : [AVSON 2110] The New FUORS from CRTS

[F L]

http://tech.groups.yahoo.com/group/AVSON/message/2110

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Last year, somewhat a little near the end of their observing season, three new
FUOR to EXOR or just plain eruptive Young Stellar Objects where brought to light
by the Catalina Sky Survey RealTime Transients Survey (CRTS).

Two of them were noted in ATEL 2307
http://www.astronomerstelegram.org/?read=2307 as well as elsewhere, one appeared
later in IBVS 5921 http://www.konkoly.hu/cgi-bin/IBVS?5921

A very nice recent ESO image of the entire Monoceros R2 region has recently
appeared as an ESO press release, with a falsecolour image derived from Y (about
1 micron) J and K band images.

http://www.eso.org/public/archives/images/screen/eso1039a.jpg (image credit :-
ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit)

To the bottom left can be found the two stars from the ATEL, about an eighth of
the way in. Patrick Wils' FUOR appearing white with the reflection nebula
seemingly apparent next to it (making the star look a little like a double) and
the more orange nearby possible UXOR / FUOR near the very lower border of the
image to lower right of that.

They can both be seen to be on the edge of an arc of faint nebulosity.

Patrick W's star is still brightening slowly I believe.

Monoceros is just returning into season again.

Near top right, topmost midright, on a line slightly left of being vertical from
the bluest and brightest star in the image, is the star from the IBVS. At the
time of noting it in CSS data the paper's referee wasn't entirely sure that it
was a star as of then, preferring just a brightening nebula knot, but still it
looked evidently stellar in most images to me. Since that time this VISTA image
has appeared.

A cutout of the field including the bright blue star is here
http://oi53.tinypic.com/1zyvcxt.jpg with the object arrowed (again, ESO image
credit as per above). It is now pretty much the brightest object in this small
grouping. Granted the VISTA image is YJK being mapped to BGR, as longer
wavelengths are usually mapped reddest, and shortest bluest, which suggests that
the Y band and J band are contributing to a fairly large degree to the
brightness, as it appears yellowish and not strongly orange or red (which would
be the case if the K band image predominated). The Y band is still around 1
micron wavelength though, so we're still not quite optical.

Cutting a postage stamp out of the above image and zooming in by enlarging eight
times and then pasting that into the figure from the IBVS we get this image
http://oi53.tinypic.com/30vodhf.jpg

Here the top row includes a red sensitive CSS discovery image at left, an
archival POSS red plate image middle, and a 2MASS K band image to the right,
which is directly above the eight times zoomed in region of the object scaled
and cropped to the same size as the other images in the figure, then its colours
made negative, then the whole thing greyscaled, but still as sourced via the
VISTA image. This is the righthandmost image of the middle row of the edited
IBVS image at the above tinypic url, overplaced upon a SPITZER image from the
IBVS figure such that it is placed so it can be directly compared with the K
band image directly above it, and with the red images of the top row in general.

Evidently the object has brightened markedly over the past year.

How much it has brightened optically is unclear and not yet known. The small
asterism of three bluewhite stars just to the south and right of it in this
image http://oi53.tinypic.com/1zyvcxt.jpg are stars of red magnitude twelve and
a half to thirteen (in CMC14 r' magnitudes). As they are bluewhite in the
colour image, most of their presence is from the VISTA Y band image. The object
we are looking at is yellowish in the image, so the J and K band is having some
contribution too, and the Y not as much. It appears similar in magnitude to
these objects, but again has more near infrared contribution than the stars do.

A pure guesstimate says it may be about 14th magnitude, or maybe only 15th
magnitude on any red sensitive CCD images of the field at present. It may be
brighter and nearer thirteenth on such a CCD if used unfiltered. Visually who
knows, though should be at least magnitude 15 or better.

And the object will still be brightening.

So three FUORs for Southern, and due to the location also Northern, observers
this summer/winter that should just keep on brightening, and more than rival the
two new ones in Cygnus. Patrick Wils' FUOR also has an interesting reflection
nebula associated with it, which may show morphological changes over time in a
manner akin to R Moncerotis and Hubble's Variable Nebula. It's neighbour
variable YSO may be visible in amateur CCD equipment, it may not, but it is so
nearby that it will likely be a freebie as it should appear in the same CCD
field. That one has been known to have deep fading events.

Meanwhile, the new emergent star appearing amidst HH 866 and its components, in
the heart of an infrared cluster, may also be changing how the emission
nebulosity in this region appears both visually and in optical imaging and in
filtered imaging, including Halpha or even more exotic spectral line filtering,
eg [SII].

Changing vistas to come, as incidentally demonstrated from ESO's VISTA by recent
images contained in this press release http://www.eso.org/public/news/eso1039/

Cheers

John
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For a change of pace