Pressure balance of LDN 1616 with hot gas inside superbubble

[will-henney]

The Orion-Eridanus superbubble is filled with hot x-ray emitting gas, which is mostly due to multiple supernova explosions over the last 30 Myr.

There is a recent paper Fuller et al (2023) with x-ray spectroscopy, which derives the thermal pressure of this gas.

Here is the most relevant figure

This shows that the pressure is very uniform, with a value of about 60,000 K/cm^3

[will-henney]

It is possible that we may plausibly reduce the pressure by a factor of sqrt(2) if the two temperature components (2 MK and 9 MK) coexist in the same volume, given what they say here

So that could give an absolute minimum value (assuming $f = 1$) of 40,000 K/cm^3

[will-henney]

We now need to compare this with the thermal pressure of the ionized gas in the globule H alpha arc, which Roberto will calculate in #4

[will-henney]

From the results of #4 we have a density of 10 cm⁻³ for the ionized flow from LDN 1616. If we assume that the temperature is 8000 K, then this gives a pressure of 2 n T = 160,000 K/cm^3

So, this is over-pressured by a factor of 4 with respect to the hot gas. This means that the photoevaporation flow would be able to carve out a small cavity