Bow-shock-size/driving-star-mass correlation

In a previous post I did map close bow shocks. Bow shocks can form either if the star moves against the interstellar dust (runaway star) or if the interstellar dust moves against the star (like in the Orion Nebula).

Most of the close bow shocks I did map do not agree with proper motion and bow shock.
Additionally the bow shocks from the Lower Centaurus Crux Subgroup do point into almost the same direction and none of them agree in proper motion and bow shock arc. My wild guess is that Supernovas and massive stars in the Loop I Bubble do produce a strong current of interstellar gas and dust and that the Lower Centaurus Crux Subgroup bow shocks are located in a tunnel connected to the Loop I Bubble.
The only bow shocks that agree with proper motion and bow shock arc are Zeta Ophiuchi, Delta Scorpii and Epsilon Persei.

lower cen-cru -to- loop I
Position of the Loop I Bubble connected to bow shock driving stars of the Lower Centaurus Crux Subgroup (Alpha Crucis is the only Spitzer image; other are WISE images)

My next step was to find a Mass-Distance-bowshockSize correlation. In other words: How does the size of the bow shock change with the mass of the star?

For this I did measure the size of the bow shock as a radius in arcminutes from the driving star. But the bow shocks often show multiple rings. This is why I did measure the smallest and the largest ring.

Beta Crucis (left/WISE) that shows two rings and Epsilon Persei (right/WISE) that shows only one ring. For both it is required to measure the smallest and largest ring or minimum and maximum.

After the measurement I did calculate the ring sizes in parsec:

rings
The larger rings do show a better mass/ring-size correlation than the smaller rings (Sigma Scorpii excluded)

rings large

So I get the formula rpc=(0.0185*M-0.0801)±0.03 and because rpc=dpc*tan(r°) you can calculate the distance if you know the mass of the star and the size of the largest ring:

dpc=[(0.0185*M-0.0801)±0.03]/tan(r°)

rpc is the larger radius in parsec, r° is the larger radius in degree, M is the mass of the star in solar masses and dpc is the distance in parsec.

You can also calculate the mass of the driving star, if you know the distance of the driving star and the size of the largest ring. Or you can calculate the size of the largest ring, if you know the mass of the driving star and the distance.

For other bow shocks you can also find largest and smallest rings in more distant bow shocks. The current bow shock catalog with 709 bow shocks do show the angular seperation between central source and bow shock. In some cases, like Beta Crucis, this is closer to the smallest ring. In other cases, like bow shock no.263, this is closer to the largest ring.

rings
Bow shock no.263 and its smallest and largest ring (left: spitzer 24μm/right: spitzer 8.0μm); the mass and distance of the driving star is not known
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s