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Kirjoittajan mukaan: Arto.Oksanen_at_hidden_email_address.net
Päiväyksen mukaan: 09.02.2004

Alla tietoa upouudesta DS-kohteesta M78:ssa Orionissa. Tarkastakaapa vanhat kuvat ja visuaalihavainnot. Milloin uusi sumu on ilmestynyt? Sumun kehittymistä kannattaa seurata.


Arto Oksanen                          arto.oksanen at jklsirius.fi
Jyvaskylan Sirius ry, Kyllikinkatu 1, FIN-40100 Jyväskylä, Finland 
Tel: +358-40-5659438                          Fax: +358-14-4157803
Nyrola Observatory   http://www.ursa.fi/sirius/nytt/nytt_info.html 

-----Original Message-----
From: Brian Skiff [mailto:Brian.Skiff_at_lowell.edu] 
Sent: 9. helmikuuta 2004 6:02
To: aavso-discussion_at_mira.aavso.org
Subject: ÄAAVSO-DISÅ Erupting star near Herbig-Haro 22

     Jay McNeil (Paducah KY) recently noticed that a new nebula has appeared
in the region of M78 in Orion.  This was observed with a small CCD camera
set-up.  Passing this information along to Herbig-Haro expert Bo Reipurth

(Univ Hawaii), it has been found that the nebula has resulted from the
outburst of an embedded star behind the thick dark clouds in the region. The event is possibly similar to eruptions of EX Lupi (prototype of the EXor variables). Material has been submitted for an IAUC announcement, but there is no reason follow-up observations should be delayed now that the Moon is getting out of the way in the evening. McNeil's Nebula (as it is being called for now) is about an arcminute across, and is essentially a new deep-sky object---and is probably a visual object. It is centered at roughly: 5 46 14 -00 05.8 (J2000). Those with CCD cameras will immediately see what's going by comparing new images with your favorite archive DSS images. The erupting variable, which is too faint (at present) to appear in McNeil's images, is located at the tapered southern tip of the new nebula, and has been observed previously only from the near-IR and longward: IRAS 05436-0007 = 2MASS J05461313-0006048: 5 46 13.14 -00 06 04.8 (J2000) ...where the position is from 2MASS. The 2MASS photometry is: J = 14.74 +/- 0.03 H = 12.16 0.03 Ks = 10.27 0.02 ...which was taken on 7 Oct 1998 (JD 2451093.8). Note the whopping red J-K color (J-K=4.5). The star appears in no visible-light sky survey image
(even at I), and was thus much fainter than red magnitude 19 at least, but
is now about R ü17. There are two somewhat brighter stars about 1'.5 northeast, in fact, the only two readily visible stars of any kind in a large area around the new object. The pair are 20" apart. The brighter, northeastern star is a T Tauri-type star of spectral type K2e. Various data are shown below. LkHA 301 = GSC 4768-0171: 5 46 19.47 -00 05 20.0 (UCAC2) 2MASS: J=10.69, H=9.66, K=9.00 +/- 0.03 V=14.8 B-V=1.3 (Lick NPM2) UCAC2: mag=14.1 CMC12: Sloan r': 13.85 +/- 0.07 (n=3) GSC-2.2: mr=12.3, mb=13.8 GSC: mb=15.8, mv=14.2 USNO-B1.0: mi=12.2 Kiso: V=14.1 The star has an approximate V = 14.5 and R = 13.9 but note that there is no genunine photometry available except the 2MASS data. (I'd have more confidence in the Carlsberg (CMC12) red magnitude if there were more observations.) The star does not appear in ASAS-3 or TASS MkIV; data in the TASS MkII 'tenxcat' are clearly for the combined light of this star and its companion. The star is not a known variable, but likely to have variations of ü0.1 mag. due to spottedness and/or flaring. The slightly fainter companion star appears to be not an emission-line star, and is possibly an ordinary star and thus suitable as a comparison star for the erupting variable: GSC 4768-0696: 5 46 18.90 -00 05 38.2 (UCAC2) 2MASS: J=11.20, H=10.17, K=9.72 UCAC2: mag=15.3 CMC12: Sloan r': 14.80 +/- 0.38 (!) (n=3) GSC-2.2: mr=13.5, mb=15.3 GSC: mv=15.0 USNO-B1.0: mi=12.6 This star is approxiamtely V = 15.5, and R = 14.5, but these are especially rough values. The 2MASS J-K color indicates the star is fairly red or strongly reddened---or both. This isn't a good set-up as far as differential comp stars, but on the other hand, the Landolt standard fields in Selected Area 97 are only 2 degrees east at the same Declination. The desiderata are perhaps obvious: VRIJHK etc photometry and spectra. Another interesting aspect is to trace the development of the accompanying nebula. Surely the region has been imaged often over, say, the last two observing seasons. When did the nebula show up? \Brian _______________________________________________ Aavso-discussion mailing list Aavso-discussionÉmira.aavso.org http://mira.aavso.org/mailman/listinfo/aavso-discussion