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From: "michael poxon" <m.poxon@virgin.net> Subject: Re: [vsnet-orion 114] (fwd) New variable Herbig Ae/Be star - GSC 4024 1501 Date: Sat, 20 Sep 2003 17:50:42 +0100 It's me that's the YSO man, John. Your S182 ioniser sounds a good object to look at. Do you happen to know what the Ionisation Stratification profile is like in its area? If memory serves me correct (and it doesn't always!) S182 is quite a 'flat' starforming region. By that I mean not as clumpy as some SFRs. Incidentally, MISV1147 is undergoing another fade at the moment. Mike ----- Original Message ----- From: "Taichi Kato" <tkato@kusastro.kyoto-u.ac.jp> To: <vsnet-campaign-orion@ooruri.kusastro.kyoto-u.ac.jp>; <vsnet-newvar@ooruri.kusastro.kyoto-u.ac.jp>; <vsnet-orion@ooruri.kusastro.kyoto-u.ac.jp> Sent: Saturday, September 20, 2003 1:07 AM Subject: [vsnet-orion 114] (fwd) New variable Herbig Ae/Be star - GSC 4024 1501 > From John Greaves: > > === > > Hi Tom > > >From time to time I'm trying to find the more exotic types of variables in you > new candidates' lists, using a touch of the astrophysicals. This is one. > > ---- > > GSC 4024 1501 is a variable Herbig Ae/Be (a young stellar object) ionising a > nearby HII region. > > > GSC 4024 1501 has a large J-Ks excess, +2.0, B-V is 0.84, it is Halpha emission > source HBH 4-9 estimated at spectral type B, is visible in IRAS and MSX5C, the > latter seeing it at bands A, C, D and E, with the last showing variability. > > It's probably the ionising source of the HII region Sharpless 182. POSS plates > show this nebula to be quite faint on red plates, so the effect the nebula has > on the background component (ie that is going to be brighter than the standard > sky background) may offset V and Ic values a bit from truth on a CCD frame, but > it is not going to be much at V, and is irrelevant to relative variation. > > Doesn't appear to be a multiple star, nor does the nebula appear to be a > Stromgren Sphere, suggesting there aren't any other B and especially O type > comes involved. No known Herbig Haro objects either, so it's not clear whether > S 182 is natal or just adjacent. > > I'm not certain which, if any, nearby Cassiopeia OB Association it belongs to, > as there are several around this bit of sky, but it does lie quite close on the > sky to star forming region [R2003] 169, which lies at roughly 1.4 kpc > (kinematic) distance. > > > > I can't remember who exactly is interested in YSOs, but I know someone out > there has a preference for them. > > Tested first by going through all the catalogues after noting it being the > reddest object on your September candidates list, then subsuently noting that > it had J-Ks excess relative to B-V. Patrick Wils kindly assessed the > observational data and light curve and confirmed actual variation. Miniscule > plot of V observations enclosed. > > Cheers > > John >
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