Literature review of photoevaporation flows for Introduction section of Roberto's thesis

[will-henney]

We should restrict the scope to evaporating globules and knots. That is, excluding blister flows and champagne flows

So the main categories of ionized photoevaporation flows are:

1. In H II regions.
   • Globules is the term generally used for relatively large molecular clumps with size around 0.1 pc. For instance, Bok globules are seen outside of H II regions, as well as inside them. These get left behind as the ionization front expands around a high-mass star, at which point they develop a photoevaporation flow. There are many examples of evaporating globules in the Carina nebula. See for instance the following papers:
     • https://ui.adsabs.harvard.edu/abs/2018ApJ...869...77C
     • https://ui.adsabs.harvard.edu/abs/2019MNRAS.490.2056R (this an example of a globule that contains a young star with a bipolar molecular outflow and jet that breaks out into the H II region)
     • http://adsabs.harvard.edu/abs/2016A%26A...591A..40S (Cygnus region, which is further away than Carina)
     • Also look at references in these papers and citations to them, in order to find additional papers
   • When they are still connected to the molecular cloud, they have the appearance of columns, pillars, or elephant trunks
     • For example http://adsabs.harvard.edu/abs/2015AJ....149..101H
   • There are also smaller globules, which are sometimes called globulettes
     • In the Rosette nebula for instance: https://ui.adsabs.harvard.edu/abs/2013A%26A...555A..57G/abstract
     • Not all of these have photoevaporation flows and they do not usually have stars inside them
   • They are also sometimes called EGGs (Evaporating Gaseous Globule). These do tend to have stars inside
     • https://ui.adsabs.harvard.edu/abs/1996AJ....111.2349H
     • http://adsabs.harvard.edu/abs/2016ApJ...825L..16M
   • Finally, the smallest photoevaporation flows in H II regions are the proplyds. These are protoplanetary disks around low mass stars that are directly illuminated by ultraviolet radiation
     • http://adsabs.harvard.edu/abs/1999AJ....118.2350H
     • https://ui.adsabs.harvard.edu/abs/2023MNRAS.525.4129H
     • These are the only previous well-studied case of interaction of a stellar wind with a photoevaporation flow
       • http://adsabs.harvard.edu/abs/2001ApJ...561..830G
       • http://adsabs.harvard.edu/abs/2005AJ....130.1763S

[will-henney]

Second category of photoevaporation flows:

2. Circumstellar molecular knots
   • Usually in Planetary Nebulae
     • For example the Cometary Knots in the Helix Nebula
       • http://adsabs.harvard.edu/abs/2007AJ....133.2343O
       • http://adsabs.harvard.edu/abs/1996AJ....111.1630O
       • Remember to also look at citations to these articles
     • Also in the Ring Nebula and other PNe
       • http://adsabs.harvard.edu/abs/2002AJ....123.3329O
       • But note that not all of the knots seen in PNe necessarily have photoevaporation flows
   • Also knots in Wolf-Rayet nebulae would also fall in this category
     • I do not know of any other cases (apart from M 1-67) but we should look into it more carefully

[will-henney]

Theory and simulations of photoevaporating globules

Analytic and semi-analytic models

1. Kahn 1954
2. Oort & Spitzer 1955
3. Bertoldi 1989 Radiation-driven Implosion
4. Bertoldi & McKee 1990 Equilibrium Cometary Clouds
5. Raga et al 2020

Numerical simulations

1. Mellema et al 1998
2. Henney et al 2009
3. Mackey et al 2010
4. Mackey et al 2011
5. Arthur et al 2011
6. Lei et al 2023