Astronomie · English version

Close Bowshocks

I searched for close bowshocks after some of our volunteers found a close bowshock, which belongs to Alpha Crucis. I found 3 new bowshock candidates and 3 bowshock candidates that are already in a bowshock catalog (Kobulnicky+, 2016).
Alpha Crucis is the only bowshock that is in the Milky Way Project (subject link).

Here the bowshocks sorted after the distance of the driving star:

Beta Crucis (2nd brightest star in the image)
distance: 85pc    sp-type:B1IV   image: WISE
wise_bet_cru

Alpha Crucis (new)
distance: 99pc    sp-type:B1V+B0.5IV   image: spitzer
alp cru

Zeta Ophiuchi
distance: 112pc    sp-type:O9.2IVnn   image: spitzer
ZetaOph_spitzer_960

Theta Carinae (new)
distance: 140pc    sp-type:B0Vp   image: WISE
wise_tet_car

Delta Scorpii
distance: 150pc    sp-type:B0.3IV   image: WISE
WISE_del_sco

Epsilon Persei (new)
distance: 195pc    sp-type:B1.5III   image: WISE
wise_eps_per

Zeta Ophiuchi is the most massive stars in this list and the only that is not a spectroscopic binary. Zet Oph is a runaway star that was once in a binary system. The more massive star exploded in a supernova and Zet Oph was kicked out of the system.
The other runaway stars are still binary systems, so their origin is probably not a past supernova.
Theta Carinae belongs to the cluster IC2602. Other stars of the cluster do not show bowshock activity.


Update 27 April 2017:

I found another 3 new bowshocks that are close:

Alpha Muscae (new)
distance: 97pc    sp-type:B2IV   image: WISE
wise_alf_mus

Tau Scorpii (new)
distance: 145pc    sp-type:B0.2V   image: WISE
wise_tau_sco

Sigma Scorpii (new)
distance: 214pc    sp-type:O9.5(V)+B7(V)   image: WISE
wise_sig_sco

Alpha Muscae does have a small bowshock for this close distance.
Sigma Scorpii does have a very bright bowshock that is also visible in the w3-channel of WISE. This way it appears yellow.
Tau Scorpii does not have an evidence for a companion that orbits the star.

The final list:

*bet Cru       85 pc        B1IV
*alf Mus       97 pc        B2IV
*alf Cru        99 pc        B1V+B0.5IV
*zet Oph      112 pc      O9.2IVnn
*tet Car        140 pc      B0Vp
*tau Sco       145 pc      B0.2V
*del Sco       150 pc      B0.3IV
*eps Per      195 pc      B1.5III
*sig sco        214 pc     O9.5(V)+B7(V)

Zeta Ophiuchi is probably the most massive and youngest star in the list (19.8 solar masses and 3 Myrs young).
Alpha Muscae is the less massive star in the list with 8.8 solar masses and the oldest with an age of about 18.3±3.2 Million years.

Most of these close Bowshocks belong to the Scorpius-Centaurus OB Association:
position

Epsilon Persei is probably the only bowshock that does not belong to this Association. I did draw the general direction (no precise measurement) of the bowshocks as red arrows in the graph. As you can see: The Lower Centaurus-Crux subgroup does move in one direction. None of these members should have a supernova origin. The Upper Scorpius subgroup is a bit messy and maybe more than Zeta Ophiuchi might have a origin in a supernova. Especially Delta Scorpii might be a system that was near the zet oph sytem when the more massive star exploded in a supernova. Zet oph and del sco point in two different directions.

Here the Lower Centaurus-Crux subgroup:

And here the Upper Scorpius subgroup:

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