Supernova 1987a

The envelope of SN 1987a will strike its circumstellar ring in 12 +/- 3 yr. after explosion (A.D. 1999 +/-3), the exact time depending weakly on the uncertain density of diffuse gas between the supernova and the ring; Luo et al

We present models for the hydrodynamics of the impact of the envelope of SN 1987A with its inner circumstellar ring and for the resulting X-ray spectra and light curves. If the impact begins in A.D. 2000...; Borkowski et al

The extensive observations of this supernova confirm it occurred 167,000 years ago

One of the main tenets of creation 'science' (at least the 'young earth creationist' or YEC version of it) is that the earth and universe are only 6000 years old. It is my purpose, in this work, to show that SN1987A is about 167,000 light years away and that the event at SN1987A occurred about 170,000 years ago. This refutes the YEC claim that the universe is only 6000 years old. In doing so, it also falsifies YEC as a scientific explanation for the origins of the Universe.

The findings of physics, astronomy and so on have long demonstrated that the universe is billions of years old, as evidenced by our ability to see stars that are billions of light years away. Creationist criticisms of this view usually fall into one of three categories:

God created the universe with the light from apparently distant stars 'intact' and in transit and so we can see them now (this is a totally unscientific explanation as it requires a supernatural act or miracle - consequently I will not address this point further in this work)

The speed of light is decreasing and hence light could have traveled much greater distances in the past (this is counter to scientific observations)

The observations of science regarding the distance of stars and galaxies are subject to error because they rely on 'indirect' measurements (such as measurements of redshift, brightness, and so on). This also runs counter to current science, but until the observations of SN1987A were made this was, at least, a debatable point.

However, an event was observed on February 23, 1987, that allows us to lay to rest the second and third creation 'science' arguments above. This event was the observation of Star 1 of the Sanduleak - 69 202 trio in the Tarantula Nebula, part of the Large Magellanic Cloud, going supernova and earning a new name: SN1987A (1). It was the most luminous supernova recorded since Kepler's star of 1604 and the first since then to have been observed in the Milky Way complex. In going supernova, it became one of the most studied astronomical objects of the last 15 years. There are more than 1700 astronomical papers that mention '1987A' in their title.

As a result of that event, we were able to make a direct trigonometric measurement of the distance to that supernova of nearly 167,000 light years. This is now the most distant object ever measured by direct triangulation. Also, other measurements have been made that confirm the speed of light has not changed appreciably since it left SN1987A.

The original paper in which Panagia et al measured the distance to SN1987A (2) is available online here.



		From the abstract of the Panagia et al paper: We have determined the distance to the SN 1987A by comparing the angular size of its circumstellar ring measured from an HST (Hubble Space Telescope) image ... with its absolute size derived from an analysis of the light curves of narrow UV lines ... measured with IUE (International Ultraviolet Explorer). Our analysis confirms that the observed elliptical structure is indeed a circular ring at an inclination of 42.8° ± 2.6°. and provides a determination of its absolute diameter (1.27 ± 0.07) x 10¹⁸ cm. Its ratio to the angular diameter of 1.66" ± 0.03" ... gives an accurate determination of the distance to SN 1987A ... = 51.2 ± 3.1 kpc.... This value agrees very well with the determinations obtained from light-curve analysis of variable stars




			An image of the circumstellar ring analyzed by Panagia et al

Thus, Panagia et al established the distance to SN1987A at 166,912 +/- 10.1 light years as one parsec is 3.26 light years, and one kiloparsec (kpc) is 3260 light years. This measurement is in good agreement with previous estimates of the distance to the Large Magellanic Cloud of 143,000 to 179,000 light years. In making this measurement, Panagia et al have effectively refuted creationist claims that distances much greater than 100 light years have not been measured accurately.

SN1987A shock wave propagation

The Panagia et al findings were confirmed when the long anticipated shock wave from the supernova explosion reached the ring. Predictions of the shock wave (3) (4) were made in papers available on line here and here.

In 2000, the shock wave arrived at the circumstellar ring (5) (6) and was reported in abstracts available on line here and here.

So, we have not only the Panagia et al findings, but confirmation of his work in the predicted arrival of the shock wave from the SN1987A event. These predictions have been made (and confirmed) independently by several astronomers. SN1987A is 167,000 light years away and its light has taken 167,000 years to reach us thus effectively refuting claims for a 10,000 year old Universe once and for all.

There remains only one other creationist objection to deal with; an alleged change in the speed of light since SN1987A went supernova. This objection can be addressed by:

Let us imagine that the speed of light was considerably greater at the time of the supernova than today. Creationists could use this supposition to suggest that light has traversed the space between the supernova and Earth more quickly than would be the case if the speed of light has been constant at the speed observed today. The argument would then go that although the distance to SN1987A is 167,000 light years, light could have traversed that distance in less than 167,000 years.

However, if the speed of light was greater at the time of the occurrence of the supernova then the absolute distance to the circumstellar ring would be proportionately more than we calculate based on the current speed of light. The angular distance from the supernova to the circumstellar ring is not in question. By comparing the absolute and angular distances, we would arrive at an absolute distance to the supernova greater than that based on a constant speed of light. This would yield a time for the light to traverse the space between the supernova and Earth the same as or greater than the time derived from a constant speed of light - ie the same as or greater than 167,000 years (since at some time the speed of light would have had to decrease to what we observe today). So a decaying speed of light offers no comfort to the creationist position.

But from other considerations, we can be sure that the speed of light has not changed significantly.

Any change in the speed of light will show up as either a change in the decay rates of short half-life radioactive isotopes or a change in the energy levels of those isotopes.

For example, if light was twice as fast at the time SN1987A occurred as now, then an isotope with a 60 day half life would seem, in spectrographic data, to have a 120 day half life. This is because the light would travel the same distance in 60 days at the time of origin, as it would cover in 120 days when it reaches Earth. Or, the energy level of those isotopes would change according to E=mc². So, if the speed of light (c) were twice as fast at the time of SN1987A as it is now, radioactive isotopes would release four times as much energy on decay as they are observed to do now..

Some of the papers supporting a consistent radioactive decay rate and energy at the time and place of SN1987A with modern, Earth bound values (7), (8), (9) are available here, here and here

Conclusion

We have now established by trigonometric measurement that SN1987A is at a distance of about 167,000 light years and verified the speed of light is not significantly changed since the time and place of SN1987A. This demonstrates that the events surrounding Supernova 1987A took place some 167,000 years ago and YEC is therefore falsified.

2. Panagia et al, Properties of the SN1987A circumstellar ring and the distance to the Large Magellanic Cloud, The Astrophysical Journal 380, L23 - L26; available on line here

3. Luo, McCray and Slavin, The impact of SN1987A with its circumstellar ring, The Astrophysical Journal 430, 264 -267; available on line here.

4. Borkowski, Blondin and McCray, X-rays from the impact of SN1987A with its circumstellar ring, The Astrophysical Journal 477, 281 - 293; available on-line here

5. Michael, Hubble Space Telescope Observations of the Shocks in Supernova Remnant SN 1987A, The Astrophysical Journal Supplement Series 12, 429-432; available on line here

6. Lawrence et al, Recent HST Spectral Imaging of SNR 1987A, American Astronomical Society Meeting 197, #82.09; available on line here

7. Hamuy et al, SN1987A in the LMC; UBVRI photometry at Cerro Tololo, The Astronomical Journal 95, 63 - 83; available on line here

8. Suntzeff et al; SN1987A in the LMC II OPtical photometry at Cerro Tololo, The Astronomical Journal 96, 1864 = 1873; available on line here

9. Bouchet et al, The bolometric light curve of SN1987A, Astronomical Astrophysics 245, 490 - 498; available on line here



		There are several links at the bottom of this page that I urge everyone to visit and bookmark, if for no other reason than they have a lot of really great images.




			We present observations of supernova remnant SN 1987A made with the Hubble Space Telescope.... Space Telescope Imaging Spectrograph (STIS) spectra confirm that this spot is the result of a ~300 km/sec shock entering the inner circumstellar ring at the first point of contact by the supernova blast wave; Michael The full-scale interaction between the blast wave from SN 1987a and its circumstellar equatorial ring (ER) has begun; Lawrence et al




				Hubble Space Telescope image of shock wave arriving at circumstellar ring




			We present UBVRI photometry of the Type II supernova 1987A .... the general shape of the bolometric light curve is close to the predicted curve based on radioactive decay of 56Co in the remnant; Hamuy et al We present ... photometry of SN 1987A in the Large Magellanic Cloud .... The bolometric luminosity has declined with an e-folding time of 100.5 days, roughly consistent with the e-folding time of 111.3 days for the radioactive decay of 56Co; Suntzeff et al We derive the ultraviolet-optical infrared (uvoir) bolometric luminosity evolution of SN 1987A .... this method is more accurate than estimates of the uvoir bolometric luminosity based on the integration of broad-band magnitudes. We show that between days 130-300 SN 1987A declined ... with an e-folding time of 109.6 +/- 0.3 days, consistent with the thermalized energy released by the radioactive decay of 56Co; Bouchet et al



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