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- It's all happening up there! - | |
A Knotty KnebulaA large multinational team working with HST performed narrow-band imaging of the AFGL 5180 nebula complex in the NIR with the Large Binocular Telescope, in both seeing-limited (~0.5") and high angular resolution (~0.09" Adaptive Optics modes, as well as with HST and archival ALMA continuum data. At least 40 jet knots were identified via NIR emission. Bright jet knots outflowing from the central most massive protostar S4 are detected towards the east of the source and are resolved in fine detail with the imaging. BP Psc: YSO or OSO?I have been in contact with Dr. Ilya Potravnov who has been studying this very strange object, in the suspicion that it may turn out to be another high-latitude YSO like V1117 Her, whose galactic latitude it exceeds (-57°!) The lightcurve from ASASSN (which in fact classifies it as a YSO) actually, even to my biased eyes, looks very similar to that of an SRd type star (i.e., not a YSO!) |
Major Fade of V350 CepThis faint object underwent a very recent fade, as observed by our member Cledison Marcos da Silva in Brasil. He says it is the second fade this year: "My last photometry for it shows a magnitude of 17.823, is the faintest I record since I started to follow this star in April". VVV-WIT-12: What Is It?We report the serendipitous discovery of VVV-WIT-12, an unusual variable source that seems to induce variability in its surrounding nebula. The source belongs to the rare objects that we call WITs (short for What Is This?) discovered within the VISTA Variables in the Vía Láctea (VVV) survey. The object was discovered during a pilot search for light echoes from distant Supernovae in the Milky Way using the near-IR images of the VVV survey, and has an extremely red spectral energy distribution, consistent with a very reddened (100 magnitude extinction!) long period variable star with a period of about 1500 days. TMC StudyWith the third data release of the Gaia mission Gaia DR3 with its precise photometry and astrometry, it is now possible to study the behaviour of stars at a scale never seen before. An India-based study developed new criteria to identify T Tauri candidates by combining the GALEX and Gaia surveys. They found 19 candidates, 5 of which are newly identified TTS in the Taurus Molecular Cloud (TMC), not catalogued before as TMC members. For some of the TTS candidates, they also obtained optical spectra from several Indian telescopes. Analysis of the distance and proper motion of young stars in the TMC using data from Gaia DR3 shows that there is a bimodal distribution with distance, having peaks at about 130 and 156 parsecs. The reason for this bimodality is due to the fact that different clouds in the TMC region are at different distances. They further show that the two populations have similar ages and proper motion distributions, and using the Gaia DR3 colour-magnitude diagram, show that the age is consistent with 1 Myr. They also find that the TMC structure is filamentary, which is also found in similar SFRs such as the Cepheus Flare. |
Additional knots are distributed throughout the field, likely indicating the presence of multiple driving sources. Sub-millimeter sources detected by ALMA are grouped in two main complexes, AFGL 5180M and a small cluster about 15" to the south, AFGL 5180S. They identified YSO candidates down to masses of 0.1 M☉, giving a density of 103pc-2 within a projected radius of about 0.1 pc, similar to those predicted by accretion models. The images reveal the complex morphology of outflow-shocked gas within the large-scale bipolar flow of a massive protostar, as well as clear evidence for several other outflow driving sources in the region.
and the G-type spectrum would appear to back this up. However, it not only has YSO-type phenomena such as the J-K colours being markedly greater than the B-V (thus showing IR excess) but also possesses a knotty bipolar jet structure. On the other hand, there is a recent body of evidence that demonstrates the opposite - that BP Psc is actually a billion-year-old star, or Old Stellar Object! 
V350 is a member of the major starforming region of NGC 7129 which also includes the active star V373 Cep. The AAVSO smoothed lightcurve shows the two fades to be about 150 days apart. I encourage observers who can go to 18th mag to follow this object closely in the coming period.