V1117 her; a second fade?
In the last issue I made a bit of a prediction that the current mini-fade of V1117 Her would be the precursor to another, deeper, fade. Having recovered from its 14th-mag minimum somewhat, as I write it is possible that the star may be entering another fade.
The rough lightcurve here shows a second possible decline, though the smoothed light-curve actually intensifies the gradient a bit.  Definitely a star to continue following as it emerges from the period around full moon.
ρ Oph: Not just a pretty picture!
Latest issue of the SFN carries a beautiful shot of the ρ Oph complex (rho is the bright triple at top left) which is one of the closest star-formation regions to us.
L1688, the dark clump towards the upper right, contains the closest embedded cluster of YSOs. Many famous and well-studied young sources, that played a fundamental role in early star formation studies, are hidden in this optical image. The L1689 cloud lies to the lower right, below L1688, while L1709 and Oph D are seen towards the center of the image, which I trust gives an impression at least of the dynamic nature of the immediate - as well as the surrounding - regions.
Picture credits: Leonardo Ciuolotti, Matteo Collina, Riccardo De Benedictis, Giuseppe Donatiello, Rolando Ligustri. |
BH CepheiI used to follow this star at the same time as the nearby BO Cep, but abandoned it due to lack of activity. Like BO it is an UXOR with a quoted range of 10.8 - 12.7 and indeed I never saw it change very much from that maximum. It appears I should have followed it after all, as it has just undergone a deep fade, observed by YSO section member John Pickett (PKT) and in fact looking at the longer-term behaviour there
appears to be a (very) rough cycle of about 3 years for these main fades, though there is also a fair amount of smaller-amplitude activity near maximum. Something for the CCD observers to monitor! As with V1117 Her, if you want to see the activity in detail, use the Lightcurve Generator. Having mentioned BO Cep, you should note that its previously-quoted range is rather too extreme and that according to VSX this is now given as 11.5 - 12.4 which I must say bears out my own results perfectly. This brings home the fact that one benefit of closer attention being paid to these stars allows us to refine their parameters.
From the SFN
PV Cep and V350 Cep: stars on the way between FUors and EXors
Based on new observations during 2015-2020 and published data, the unusual eruptive variables PV and V350 Cep were examined by Andreasyan et al. It is shown that PV Cep underwent a regular outburst followed by a drop in brightness that lasted overall from 2011 to 2019 and is still in a deep minimum. The outburst was accompanied by substantial changes in the intensity and profiles of a number of lines, including Ha, [SII], and [OI]. The forbidden lines generally have negative radial velocities and can be divided into four components, with variable velocities and relative intensities. V350 Cep essentially is at a maximum brightness level over the entire time and its spectrum is practically unaltered. The available data suggest that the pronounced P Cyg profile of the Ha line in the spectrum of V350 Cep appeared several years after the luminosity rise, in 1986. The luminosities of the stars in the current state are estimated to be 20L☉ and 3.3 L☉ respectively. It is concluded that both stars may represent intermediate objects between the FUor and EXor classes.
PV Cep is the 'runaway' star that is ploughing into Gyulbudaghian's nebula by the way. |
