Astral Insights May 2024
A Cepheid Variable and a Supernova 1A walk into a bar…
The cosmos, as we now know, is quite lively and far from static.
Down here on earth, things are also quite lively astronomically. There is an ongoing debate about a problem known as “Hubble’s Tension” (as if we don’t already have enough tension). It concerns the way the expansion rate of the universe is determined labeled as H0. Two teams, NASA and ESA, have come up with two different values. One, using NASA’s Hubble and James Webb telescopes come up with a value of 74.3 +/- 1.0 (km/s)/Mps {kilometers per second per Megaparsec} The other, using the ESA’s Planck mission, came up with 67.4 +/- 0.5 ( km/s)/Mpc. Both numbers incidentally are a long way from Edwin Hubble’s own initial wildly inaccurate estimate of about 500(km/s)/Mpc.
The NASA team base their estimate of the expansion rate on the use of a standard candle of the closer Cepheid Variable and the fixed brightness of the more distant supernova 1A. A standard candle is used to determine astronomical distance. One way is by correlating distance to the well-established brightness changes of a cepheid variable. For larger distances we use the well-established fixed luminosity of a supernova 1A. Over repeated observations, changes in these measures would be observed and evaluated. An expansion rate could then be derived from those analyses.
ESA uses a method based on the Cosmic Microwave Background (CMB). Its Planck mission, launched in 2009, was designed to study the fluctuations in the CMB. Its purpose was to better understand how the universe expanded from the time of the Big Bang to now. That backward look is what forms the basis of their estimate.
In a sense NASA is looking at expansion of the universe now, while ESA is looking at its expansion from when it first came into being. Assuming that both teams have assiduously reviewed their data and confirmed their results, the question on everyone’s mind is what accounts for the difference.
Cosmologists parade the “usual suspects”. Dark Energy, Dark Matter and gravitational anomalies are the top contenders.
In April 2024, Wendy Freedman et al reported yet another possibility.
She presented a paper at the April 2024 meeting of the American Physical Society. It involved new data obtained from the James Webb telescope. Her contention: the Cepheid variable indexing may be off.
Her team determined Hubble’s Constant from JWST observations of dying stars which are labeled TRGB (Tip of the Red Giant Branch). Their values come in at around 69(km/s)/Mpc. As seen below, the dispersion of the TRGB data overlays nicely with the Planck values and less with the Cepheid values. This hints at indexing issues with Cepheids. As usual, more study is needed.
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Too Hot to Handle
Several missions are being planned for Venus. Apparently, NASA had canceled a flight back in 2022. But intense pushback from an array of NASA personnel and others, convinced the administration to reverse that decision. (DAVINCI – NASA Venus Flyby and Probe (2029), VERITAS – NASA Venus Orbiter (2031) EnVision – ESA Venus Orbiter (2031))
What was so compelling to make NASA change its mind especially in light of its budgetary constraints? Global warming.
Venus, in many ways, is a kind of sister planet to earth in terms of size, mass and orbital parameters. Yet its hellish atmosphere and surface indicate that our two planets took very different paths to the present. The fact that Venus is closer to the sun cannot account for the tremendous surface temperature differences. Current studies indicate that our atmospheres emerged from similar types of volcanic activity in the eons past.
Weller et al studied the atmosphere because they felt it would provide clues about the interior evolution of the planet. They found an abundance of nitrogen and carbon dioxide.
Previous studies had conclusively demonstrated that such atmospheric gases can only be a result of tectonic activity on the planet’s surface. Such processes lead to extensive volcanic activity with a concomitant out-gassing of these molecules. This is a geologic history similar to
that of the earth. At some point in time though, Venus underwent accelerated global warming to the point that the temperature on the surface of Venus became hot enough to melt lead. While this is not yet a likely outcome for us, scientists are most interested in figuring out what happened. They hope to glean any insights that can help us better manage our own global warming.
“Cold Hands Warm Heart”
This catchphrase of many a love song may apply just as well to two dwarf planets in the Kuiper Belt: the donut shaped ring of planetary material just beyond Pluto’s orbit (see above photograph).
Studies of Eris and Makemake indicate an icy surface that subsumes hot thermal activity in the interior. Planetary scientists often focus on the makeup of methane on the surface of a dwarf planet. A particular ratio of methane is Deuterium/Hydrogen (D/H). While hydrogen has just one proton, its isotope, deuterium, has one proton and one neutron (Heavy water). As noted in their paper:
“The D/H ratio on a planetary body yields information about the origin, geologic history and formation pathways of compounds containing hydrogen” (C. Glein et al: Southwest Research Institute)
Until recently, it was believed that the icy surface of these dwarf planets would possess high D/H values. This would indicate that the source of the surface methane was from primordial solar nebula. (In other words, from the
outside.) But, using data from the Webb, they found that
the ratio was moderate, and significantly less than
expected. This implied that the methane had to have an interior source: geothermal activity. That is of significance because it might indicate the presence of water and potential habitability for us. See:
https://www.sciencedaily.com/releases/2024/02/240215142301.htm
In case you were worried
Amidst the turmoil on our planet, there are lots of cool headed people who spend their days scouring the heavens, looking for potential threats from asteroids colliding with the earth. Generally, objects more than 140 meters in size, coming within 7.5 million kilometers of the earth’s orbit are those in what the medical field call ”concerning”. It turns out there are lots of these and any number of scientific and governmental agencies are monitoring them. So far, the combined analysis indicates that there is no known threat for the next 100 years.
For a more detailed exploration go here.
