The Planet
Sirius Ab located 8.3 light years from Earth.
Geudes
et al(2007) discusses the probability of exoplanets existing on the
alpha Centauri system,which is closest to Earth at 4 light years,
based on projections using a computer algorithm. [1]
In
their paper are various mathematical algorithms that seem to predict
over an extended period of millions of years the formation of planets
that go on to stabilised orbits and with finite, rocky natures and
orbits at various distances from the binary. The other companion,
Proxima Centauri is not considered as the influence at 10,000AU is
minor on the main pair.
In
this paper, I use the projections of Guedes et al and include the
Sirius star system which is binary, Sirius A being twice the mass of
our Sun and Sirius B , a white dwarf companion, as massive as the Sun
but about the size of the Earth. [2]
Further, the system is a S-type where the planet orbits Sirius A only and not P-type.
Further, the system is a S-type where the planet orbits Sirius A only and not P-type.
For
a P-type situation, the orbital mechanics would indicate a stabilised
orbit at twice the separation of the binary pair and this amounts to
40 AU or more and this corresponds to being out of any habitable
zone. Planets may exist at this distance but they have not been seen
so far for nearby star systems. Sirius B has a closest approach distance of 7.5 AU and therefore any planet existing and orbiting around SiriusA would need to be much closer, say about 6 AU in order to be in a stable orbit not severely affected by the white dwarf.[5]
Alpha
Centauri AB
The
system is unique because both companions are sun-like stars with
similar masses and no detectable planets as can be seen presently
from Earth. Using the B companion, Guedes et al has gone on to
collate probability of planet formation in the event of the formation
of a protoplanetary disc, an embryonic solar system, that will go on
to coalesce to form the planets.
I
would suggest that in doing so, they have set a model on which my
projections on the Sirian star system can be similarly used. But
there are variations and complications. To avoid going into detailed
orbital mechanics, I have simplified the approach, making it as least
technical but nevertheless detailed enough for the professional
astronomer to pursue for further study at will.
Complications
These
are:
- Sirius AB is a binary with a 50.09 year orbit of the white dwarf companion.
- Sirius A is more luminous than the Sun and twice as massive.
- Orbital stability considerations limit any planet formed near Sirius A to orbits which would not interfere with the returning white dwarf, Sirius B.[5]
- This in itself means that no stable orbit or planet can exist that is suitable for life further than a certain distance from the Sirius A – the distance calculated from some papers indicate at least a separation from Sirius B by 1.5 AU.
- Planets formed at Sirius A therefore can only be within the orbital distance from its parent at maximum of distance 6AU before serious perturbations result from Sirius B's gravitational pull.
The left figure indicates what an astronaut might see upon entering the
Sirius system. The planet b orbits Sirius A whilst the orbit of
Sirius B is located into the plane of the paper and the whole system
then orbits around its barycenter.
Based
on the projections of the paper by Guedes and Quintana, we can expect at least 1
earth analog planet for Sirius A. His paper indicates roughly the
formation of bodies that are rocky at various distances from the
Alpha- Centauri system and there is probability of an Earth analog
which might be in the habitable zone of the star. I posit that 3 planets exist with their distances as shown in the image above. Only one planet,b, is in the habitable zone.
The white dwarf has successfully cleared any debris resulting from planet formation.
The white dwarf has successfully cleared any debris resulting from planet formation.
Calculation
of Habitable Zone for Sirius A
The
calculations shown below are for the SiriusA system and are
referenced from [4].
where L is the stellar luminosity in solar units,Teff is the stellar effective temperature in K units, in this case 9900K,Ts= 5700 K, ai = 2.7619e-5, bi = 3.8095e-9, ao = 1.3786e-4, bo = 1.4286e-9, ris = 0.72, and ros = 1.77. The L value for SiriusA is 25.4.
The
habitable zonal exoplanets boundaries lie between both r values.
The values after calculations are: ri
of 2.705 AU and ro
of 5.875AU respectively.
Calculation
of orbital radius for planet SiriusAb
Based
on an assumption that a planet exists on SiriusA and that it has a 5
year period around this star, we can determine if this theoretical
planet can be in the habitable zone of the star and hence possibly
have liquid water for life as we know to exist.
Using
the Kepler's formula for orbital period of a body in elliptical
motion
- where T is period in years, a is semi-major axis and μ is standard gravitational parameter,we derive a value for a of 3.766AU for this planet.
The
habitable zones distance (HZD) is given as the formula above,
where r
is the distance of the exoplanet from the
star in AU units and HZD is the HZD in HZU units. HZD values between
-1 and +1 HZU may correspond to planets within the HZ.
Based on the values we obtained for SiriusAb, we can punch this into the above equation and we get a value that is very close to 0. The actual value is -0.328.[4]
A value greater than plus 1 indicates that it is out of the zone. But our planet seems to have just made it! From this reading it is quite a close value to Earth's, which has a value of -0.46.
Based on the values we obtained for SiriusAb, we can punch this into the above equation and we get a value that is very close to 0. The actual value is -0.328.[4]
A value greater than plus 1 indicates that it is out of the zone. But our planet seems to have just made it! From this reading it is quite a close value to Earth's, which has a value of -0.46.
Orbital
resonances
Drawing
from our own solar system, we have the inner planets having a
resonance of 1:2:4 for Earth,Venus and Mercury. Gliese 876 with
planets e,b and c are similarly in a 1:2:4 resonance.[6] It can be
assumed, although prematurely' that a similar resonance does seem
possible for SiriusA. Therefore I postulate the existence of at least
2 more planets with periods of 2.5 years, and 1.25 years on Sirius A
and these can be called planets c and d respectively.[6]
Planet SiriusAc is 2.37AU and planet SiriusAd is 1.5AU. The values are calculated from the formula from Kepler's 2nd Law.
Planet SiriusAc is 2.37AU and planet SiriusAd is 1.5AU. The values are calculated from the formula from Kepler's 2nd Law.
The planetary systems showing Habitable Zones in green.
(Courtesy Astronomy Magazine 2014).
Life in High
Light Intensity Environments
Any
life in the system must be heavily screened by the presence of a
thicker ozone layer as well as an X-ray deflection or scatterer.
The
amount of UV given off by Sirius A would be very large and to protect
the planet's ecosystem, a thicker atmospheric coat of ozone
would be very important. A thick atmosphere would also shield the
planet by scattering harmful radiation such as X-rays which will be
at a peak every time the Dwarf companion returns every 40 years or
so (period is 50.09 years). Sirius B is an X-ray source.
In
order to prevent overheating of the planet, the presence of oceans
and hence water will act as a heat sink as well as moderate the
temperature of the planet. Any greenhouse gases will play a significant role in the heat cycle on the planet.
From this
information it can be realized that the planet SiriusAb is therefore
about 20 to 40 % larger than Earth.
Thermal infrared spectra of
Venus, Earth, and Mars. The 9.6-micron band of ozone is a potential
bioindicator. (From R. Hanel, NASA Goddard Space Flight Center.)[3]
At
very high light intensities, we could expect that life would take
several options in order to exist and these are:
- The production of very strong pigmentation to prevent cellular damage by the star's intense radiation.
- Going underground or deeper into seas to shield from harmful rays.
- DNA repair mechanisms that can repair damage and enhance protection in ways unknown to humans at present.
- Cocoon life that would go into hibernation for years especially when the dark star companion, Sirius B, approaches. Its orbital period is 50.09 years. This means that upon its closest approach its time to swing past Sirius A could be in the region of a few years. This would be a “Dark Phase” in this planet's history as Sirius B is an X-ray source.Theory becomes Dogma!
Presence of moons on this planet will result in significant shielding in the planetary ecosystem as this will limit the chaos caused by shifting tectonic plates as the white dwarf approaches as well as limiting tidal fluctuations be they magma or water.
Many
astrobiologists suffer from the Billion-year syndrome. Yes, its a
billion or more years for a star to form a planetary system that can
go on to produce possible life.
Were
they there to see it? Just as the theory of evolution has now become
a fact in most scientific circles because this makes the NO GOD NO
MAN genesis all the more believable.
There
is absolutely NO PROOF that the theory of evolution is fact. Just as
there is absolutely no proof that a planet takes a billion years or
more to form!
Planets
form when conditions that favor formation are there. They can form in
deep space without even a star present for light years. These are the
rogue planets. There have been quite a few discovered so far. Were
they from other star systems and were ejected out? Were they from a
supernova explosion which cooled to reform a main pulsar possibly
and then some planets? Theory again. Then let me make a good guess.
The Crab
Nebula and Pulsars
The Crab Nebula in Taurus, exploded in 1054 AD and has a pulsar present. It is no large imagination to realize that the seeds of this supernova have sown planetary debris which will have accumulated into planetesimals. I would urge all astronomers to look at this system and it will be confirmed that there are planets forming or already existing.
This therefore will confirm that Planets do NOT take billions of years to form.
Evidence from supernova explosions indicate that planets form geologically very soon after and there is evidence to suggest that the time period is in the thousands of years! This will account for the existence of 2 billion planets as projected in some estimates.
In 2006, an MIT scientist, using the Spitzer telescope, and colleagues discovered a planetary circumstellar disc orbiting a magnetar as shown above (courtesy wikipedia). The star went nova about 100,000 years ago and is about 13,000 ly from Earth.
 | |
| Magnetar illustration |
This therefore will confirm that Planets do NOT take billions of years to form.
Evidence from supernova explosions indicate that planets form geologically very soon after and there is evidence to suggest that the time period is in the thousands of years! This will account for the existence of 2 billion planets as projected in some estimates.
In 2006, an MIT scientist, using the Spitzer telescope, and colleagues discovered a planetary circumstellar disc orbiting a magnetar as shown above (courtesy wikipedia). The star went nova about 100,000 years ago and is about 13,000 ly from Earth.
REFERENCES
- Formation and detectability of terrestrial planets around αCentauri B. Geudes et al(2007). Astrophysics Journal,679:1582-1587.2008 June 1st.
- Piercing the glare: A direct imaging search for planets in the Sirius system. Thalman et al , Astrophysical Journal Letters, 732:L34(5pp), 2011 May 10th.
- Kasting, J. F., Whitmire, D. P., and Reynolds, R. T. (1993). Habitable zones around main sequence stars. Icarus, 101, 108-108.
- Habitable Zone Distance (HZD) A habitability metric for exoplanets - Planetary Habitability Laboratory.
- The ultimate cataclysm: the orbital(in)stability of terrestrial planets inexoplanet systems including planets in binaries.Elke Pilat-Lohinger. Intl Journal of Astrobiology8 (3): 175–182 (2009).
- Rivera, Eugenio J.; Laughlin, Gregory; Butler, R. Paul; Vogt, Steven S.; Haghighipour, Nader; Meschiari, Stefano (June 2010). "The Lick-Carnegie Exoplanet Survey: A Uranus-mass Fourth Planet for GJ 876 in an Extrasolar Laplace Configuration"
