The Government begins tracking the families of known telepaths. Friction with the Belt Alliance quickly led to legal restrictions on that organization. Firsts space skirmishes involving Earthforce ships expressely conceived for combat purposes; First utilization of a space fighter, the Lockheed-Mitchell SA-5 Dauntless, that proofs itself vastly superior to the roughly adapted pirat units.
Discussion The complex atomic spectra exhibited by M-spectral type, dwarf stars have long proved a problem against the measure of their metallicity see e. Indeed, the presence of strongly blended molecular lines, and the intrinsic faintness of M dwarfs in general, make the determination of the continuum a distinct challenge, and accordingly no detailed metallicity analysis has ever been published for Proxima Centauri.
It is because of this presently insurmountable problem that a secondary method for determining the metallicity of Proxima has been investigated. Indeed, stellar models have long been used to estimate individual star masses, fundamental star characteristics and cluster ages, and the model-matching method has been highly successful in the case of a Cen A and a Cen B [ 89 ].
One of the issues with respect to computing models for very low mass stars, however, is that of describing their atmospheres. This is important not only for setting the outer boundary conditions needed for solving the equations of stellar structure, but also for describing the photometric properties of such stars.
Accordingly, as a test for consistency, the output specifically radius, temperature and luminosity for a given mass from the Ez-Web models have been compared against those published by Brocato, Cassisi and Castellani [ 21 ], Cassisi [ 22 ], and Baraffe et al.
Encouragingly, the Ez-Web models are found to be in very good agreement with these earlier publications. This consistency between models which incorporate different in-put physics and model atmospheres is partly due to the fact that the stars in the mass range of interest here have fully convective interiors, and that the models of such stars are not sensitive to the otherwise uncertain values associated with any adopted mixing-length theory [ 24 ].
Indeed, the low Invoking an old-thin to thick-disk origin for Proxima means, however, that we are beginning to play against the odds with respect to its presently observed location and space velocity.
The odds of Proxima being located at its present distance from a Cen AB are of order 1 in 57, [ 35 ]. For all this, however, these low probability results, while not necessarily encouraging, may simply be the result of Proxima having had an unusual dynamical history [ 6 ].
In addition to its closeness to the solar system, Proxima has also been observed as an active flare star [ 2627 ], although how it or, for that matter, any other M-spectral type star generates and maintains a long-lived and coherent magnetic field is still not fully understood [ 2810 ].
Haywood further finds that those stars in the metallicity range of interest here have ages between 6 to 8 Gyr. The fact that Proxima is an observed slow-rotator, with a spin-period of The results presented in this analysis, at face value, do not greatly alter the habitability zone characteristics that apply to the newly discovered planet Proxima b Anglada-Escude et al.
They do, however, carry the profound implication that the planet may be several billions of years older than assumed on the basis that Proxima formed in a coeval manner with a Cen AB. Accordingly, the planetary interior models and the status of any atmosphere associated with Proxima b see, e. Additionally, there would be no reason to suppose that Proxima has had any influence upon the growth of potential planets around either a Cen A or a Cen B.
Conclusion It has been argued in this paper that the uncertainties associated with the present day observational values for the mass, radius, temperature and luminosity of Proxima Centauri are sufficiently well constrained that the Vogt-Russell theorem, as associated with the equations of stellar structure, can be invoked as a means of estimating its metallicity.
For the theoretical evolutionary models and the observations to be brought into any reasonable agreement, we find that Proxima must have a significantly lower heavy-element abundance metallicity than that derived for either a Cen A or a Cen B.
From this we infer that Proxima did not form at the same time or in the same location of the galaxy as the a Cen AB binary. Indeed, we find, that the deduced mass, radius, temperature, luminosity, and age are not consistently explained with respect to the theoretical evolutionary models when Proxima Centauri has the same chemical abundance as a Cen AB.
The resolution of this problem lies within the continued improvement of the techniques of observational analysis e. If the inconsistency between the numerical models assuming a composition similar to that deduced for a Cen A or a Cen B and the observations continues to hold, however, then we can only conclude that Proxima Centauri is not alpha-Centauri C.
Indeed, we find that while Proxima Centauri may well be our closest stellar neighbour at the present epoch, it still presents us with many challenges that have yet to be clearly resolved. Acknowledgements A great debt of thanks is offered to Richard Townsend and the Ez-Web consortium for making their stellar evolution code publicly available, and for their excellent, user friendly, web-based interface to go with it.
A journey through time and space: Alpha and Proxima Centauri: Mathews, R and Gilmore, G. Are Proxima and Alpha Centauri gravitationally bound? The orbit of Proxima Centauri:The first interstellar object detected in our own Solar System, ‘Oumuamua has a pleasing name, translating from the Hawaiian as something like ‘far visitor first to arrive,’ or words to that effect.
This is my last post for the Bad Astronomy Blog on Discover Magazine.
As of today – Monday, November 12, – the blog has a new home at Slate magazine.. It has . Aug 29, · Proxima Centauri is about light years away from the Earth. Our Sun is about light minutes away from the Earth.
This makes Proxima Centauri(PC) about x 10^6 times farther away than our Su. "Proxima Centauri" is a science fiction short story by American writer Murray Leinster, originally published in the March issue of Astounding Stories. Unusually for the time, the story adhered to the laws of physics as they were known, showing a starship that was limited by the speed of light, and which took several years to travel between the stars.
Apr 29, · This is the bi-weekly visible open thread (there are also hidden open threads twice a week you can reach through the Open Thread tab on the top of the page).
Proxima Centauri is a red dwarf, these stars have less than half the mass of our sun. At light years away Proxima Centauri is the nearest star to the sun, but as it is so small and dim it cannot be viewed with the naked eye.