203 replies to this topic

[VY Canis Majoris]

Looking closer at the IRTF spectrum, there is perhaps some evidence for extreme mass loss. SiO lines at 4.0-4.3 μm usually appearing in absorption appear in emission, and the slope decreases dramatically at 4.5-5.0 μm while it usually stays roughly constant. A mass loss of 10^-4 Msol/yr or greater might be required to explain the observed spectral features.

 

For reference, I used Figure 4 in https://ui.adsabs.ha...A..76G/abstract.

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Edited by VY Canis Majoris, 02 February 2023 - 04:25 AM.

[VY Canis Majoris]

A non-traditional outburst by a hypergiant?

The current evidence makes the outburst of RW Cep like nothing seen before in hypergiants, nearly all outbursts are characterized by increased mass loss which increases the observed strength of TiO, something not seen in RW Cep.

They also always tend to evolve to become significantly cooler, when RW Cep doesn't seem to have changed temperature at all.

Shell ejections appear to be shells of material moving outwards, hence the name. Therefore they should always cause the observed radial velocity to decrease, opposite to what's observed in RW Cep.

I know we should wait until the event has finished but current evidence just doesn't seem to line up with other hypergiant dimming events, later data might only increase the discrepancy.

[VY Canis Majoris]

It is clear that there is either matter infall or an assymetric ejection appearing to move away from us due its angle.

[VY Canis Majoris]

Taking some mid-IR photometry might be useful, how would we go about doing this?

Edited by VY Canis Majoris, Yesterday, 04:22 AM.