Stellar-Wind Luminosity.
Abstract
The steady ejection of matter from stars by hydrodynamic expansion requires power to remove the matter from its gravitational binding, to elevate the photospheric temperature to its asymptotic plasma temperature, and to disperse the matter with its asymptotic velocity. This power is logically a bolometric correction inasmuch as it is an optically invisible luminosity. Except for ionization change, magnetic energy, and hydromagnetic waves, its value is M3 N0k dM (T~-T~)+'2v~ dt Consider the sun: if the solar wind is characterized by a mass loss of 10-13 Mo./yr at an asymptotic (1 a.u.) velocity of 400 km/sec and temperature 3 X 10~ 0K, the corresponding powers are 1.2 X 1028, 3 X 1026, and 5.1 x 10~~ ergs/sec, giving a total solar- wind luminosity equal to 0.5 X 10-~ L . Other stars are observed to lose mass at rates up to 106 times greater than for the sun, although most stellar winds are so far unobserved. Any large bolo- metric correction required have this implication for stellar evolution and the interpretation of the H-R diagram: viz, All stars arrive at a given evolutionary state faster than in the absence of mass loss. This effect is different from, but complementary to, that operable in old clusters (Clayton, D. D., Astrophys. J. 140, 1604, 1964). Specifically: (1) Contraction to the main sequence is accelerated by the T Tauri phase. (Kuhi, L. V., Astrophys. J. 140, 1409, 1964.) (2) Main-sequence lifetimes for given final mass are reduced. (3) The optical shape of the subgiant branch may be distorted. (4) Cooling of central stars in planetary nebulae to white dwarfs is accelerated. In this application the mass-loss luminosity may be indistinguishable from the neutrino luminosity; L =L~+Lp+Lrn. The gap (100 Lo.~1 Lo.) could be shot by dM/dt 10-8 M0/yr for about 10~ yr, as well as by the plasma neutrino mechanism. (Vila, S. C., Astron. J. 70, 695, 1965; Chin, C., Chiu, H., and Stothers, R., preprint). This research was sponsored by the Air Force Office of Scientific Research, Office of Aerospace Research, U. S. Air Force, under AFOSR Grant No. AFOSR 855-65.
- Publication:
-
The Astronomical Journal
- Pub Date:
- February 1966
- DOI:
- 10.1086/110036
- Bibcode:
- 1966AJ.....71Q.381C