Some interesting comments by Dr. Ron Samec from a recent science meeting concerning the sun.

 

Blessings, Laurence

          At the 2004th Meeting of the American Astronomical Society in Denver Colorado, held May 30 to June 3, 2004, Dr. Ed Guinan of Villanova University gave a brief summary on his long study of “The Sun in Time”, at session 36: "The Stellar-Solar Connection: What stars teach us about the Sun?"  This thorough study has centered on identifying solar analogues and twins at various ages in their evolution as determined by their rotation rate (stars spin down with age) and position on evolution tracks in the HR diagram.  He has been observing spectra in the IR, visible, UV, FUV, EUV, and X-ray’s from nearly every recent observatory spacecraft. While I don’t trust in the absolute ages given by these studies, the results have given both the creationary and noncreationary astronomer some interesting points to ponder. I will list a few of the important results here.

 

I. The “Young Sun” is much less luminous than our Mature Sun

At an age of 130 Myr, it was 68% as luminous. Thus 4.4 Bilion years ago, the forming solar system was a much colder place. For the first billion years, overlapping the time when the first life on earth (3.85 Billion years ago²) was supposedly emerging, the Sun was at 70% of its present luminosity and the earth would  have been a frozen orb, outside the habitable zone of the Sun. We know this as the “Early Faint Sun Paradox” as discussed by Guinan and others over the years (See Faulkner³.). Carl Sagan was noted for his post humous publication with Chyba of a supposed solution to this problem⁴, involving ammonia as a green house gas with a methane smog to protect the ammonia from photodissociation in the young earth’s atmosphere. About this explanation, Pavlov et al.⁵ used methane as a greenhouse gas to try to explain the paradox effect. Regarding such models, Dr. Danny Faulkner⁶, a noted creationist astronomer, states, “The precise tuning of this alleged co-evolution is nothing short of miraculous. The mechanism driving this would have to be a complex system of negative feedbacks working very gradually, though it is not at all clear how such feedbacks could occur.” 

 

II. The “Young Sun” is extremely Active

          Observations by Guinan of solar analogs EK Dra and 47 Cas showed 28 violent flares in a 7 day observing run⁷. These flares were 100-1000 times stronger in the EUV than the Sun’s and displayed coronal plasmas with temperatures of 20-30 million Kelvin, nearly twice as hot as the core temperature of the Sun. These flares have an energy of 10³³-10³⁵ ergs. The young sun is likely to have 2-5 such violent flares per day!

          This enhanced activity is due to the action of the young suns excessively fast rotation on its stellar dynamo. The rotation rates are on the order of ten times faster than the present Sun. Our Sun has a rotation of about 28 days. The X-ray emissions are 100 times stronger, and the solar wind density was 500 – 1000 times as massive, causing the Young Sun to loose about 2% of its mass in its early life. The mass loss for the sun at an age of 100 million years as determined from young solar analogs is 200-10,000 times its present rate.⁸ This powerful solar wind would erode a planetary atmosphere by sheer aerodynamic drag. The X-ray, EUV and FUV emissions cause disastrous photochemical effects and photoionize an atmosphere stripping away the atmosphere and in particular its ionosphere. 

          This erosion is believed to have not only ablated Mercury’s atmosphere, but eroded its crust and much of its mantle leaving little of its original material and its irony core intact, which is nearly the same size as Earth's. Some ablation is even observed today.  On Mars, the effects did not start until it lost its magnetic shield (estimated as at least 3.9 Billion Years ago⁸) and its water dissociated and the hydrogen escaped the atmosphere and the oxygen went into it rocks giving the red color of the surface of Mars.

          Only the Young Earth’s very strong magnetic field could have halted much of the winds destructive activity.  But heavy auroral activity and electromagnetic storms would be the order of the day. The ozone levels may reach very high values further cooling the surface temperature. The  high energy photons discharged by the Sun would have devastating effects on the upper atmosphere.  Guinan⁹ hopes that the photochemical effect of the fantastic X-ray and UV irradiance of the Earth's would influence the methane abundance favorably to aid Sagan and Chyba’s⁴ and Pavlov et al.'s⁵  weak models.

          Some from the crowd of astronomers at the meeting asked an interesting question. He repeated the well known 'fact' that the magnetic field of the Earth changes polarity periodically, similar to the Sun but much more slowly. What would happen to the sun when the magnetic field was zero or near zero during its regular oscillations? Would not that leave the Earth unshielded from the fantastic flaring and the dense coronal mass emissions of the young Sun? Would that rip away the atmosphere and boil away the oceans etc.?  He was answered with a statement something like, “Well, we still have an atmosphere and oceans so I suppose it did not!” Regardless, the frequent collision events called for by geophysicists prior to 3.2-3.5 Billion years ago^2,10, make the prospects for life gaining a foothold, bleak.

          Early Solar analogs have variability’s of 3-4% at the very least compared to the suns 0.1%. All this shows that our sun has “apparent age”, it is a mature, quiet star able to sustain and nourish life on earth. It does not have the marks of a young solar analog.

 

III. The Sun is Unique

          The sun has been promoted as an average, ordinary star. However, among stellar populations it is in the 99^th percentile for its mass and as more dwarf stars near the stellar limit become known it may well end up in the 99.9^th percentile! It is not a mundane, ordinary star. If it were a very average star, you would expect there to be many solar analogs (stars broadly similar to the sun) and even twins (stars that match the suns characteristics). After many searches of solar like stars among multiplied thousands of stars, only a few solar twin candidates have emerged. And, only one star, 18 Sco nearly matches the spectral and irradiance characteristics of the sun. Its night to night variation in brightness is only ~0.3%, similar to that of the Sun. But even 18 Sco’s chemical abundance pattern of some 25 elements is decidedly non solar. Also, it is somewhat displaced upward from the Sun on the HR diagram, making its age about 6 GYr.

          Other characteristics make the Sun unique: Ages of stars may be statistically determined by their velocity. Stars are thought to pick up kinetic energy from clouds of dust and gas that swarm past them.  However, the Sun has a decidedly low velocity with respect to the Local Standard of Rest (the average motion of nearby stars.) Also, the vast majority of suns appear to have stellar companions. The absence of companions sets the sun apart. Another problem is its lithium abundance. The sun’s low surface abundance of lithium does not match up with its rotation age.  Indeed, among 100,000 normal stars it has been estimated that there are less than 5 solar analogs!

 

IV. The Sun is exceptionally Stable

          The Sun has a weak 0.1% variability though its 10 and 12 year bimodal sunspot cycle and perhaps up to few tenths of a percent in short term variations due to dark spots and faculae (hot white regions).  Interestingly, the sun is in a very quiet region of the H-R diagram. It is exceptionally stable. As Dr. Radick asks¹, “Why is the Sun so smooth? And further, “Is the Sun just well behaved?”

          As creationary scientists and Christians we know why the Sun is so well behaved, while providing life giving warmth to the earth and its inhabitants.  Isaiah 45:18 For thus saith the LORD that created the heavens; God himself that formed the earth and made it; he hath established it, he created it not in vain, he formed it to be inhabited: I [am] the LORD; and [there is] none else.