Here is a selective roundup of recent research news in the field of astronomy. The focus of this set of stories is molecules found in distant galaxies, stars and planets, the stuff of life.
But first, here is a simplified description of the life of stars as crucibles where heavier elements get forged out of Hydrogen and Helium atoms -
- In early stages, stars “burn” Hydrogen, fusing them into Helium and then into heavier atoms like Oxygen and Carbon.
- Once a star like the Sun has exhausted its nuclear fuel of Hydrogen and Helium, its core collapses into a dense white dwarf and the outer layers, containing heavier elements (up to Iron), are expelled as planetary nebulae.
- Stars with around ten or more times the mass of the Sun can explode as a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole, while elements heavier than Iron are created and expelled into the neighborhood, creating material for the formation of planets, complex molecules and the ingredients for life.
- The explosions themselves can disturb neighboring giant molecular clouds and trigger new star formation.
- Our own Sun is theorized to have formed from such a molecular cloud with one or more nearby stars exploding as supernovae.
Water and Complex Molecules Jetting Away from Proto-Stars
As reported at public.nrao.edu/…, a team of scientists using the the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has uncovered jets of warm (heavy) water vapor streaming away from a newly forming star. The researchers also detected the “fingerprints” of a large assortment of molecules near this stellar nursery, including glycolaldehyde, the simplest sugar-related molecule. Glycolaldehyde is one of the ingredients in the formation of RiboNucleic Acid (RNA).
The star is located in the Cat’s Paw Nebula (aka NGC 6334I), a star-forming region located about 4,300 light-years from Earth in the direction of the southern constellation Scorpius.
As stars begin to form out of massive clouds of dust and gas, the material surrounding the star spirals into the star. A portion of this material, however, is propelled away from the growing proto-star as a pair of jets, which carry away gas and molecules, including water.
Pair of Colliding Stars Spill Radioactive Molecules into Space
From public.nrao.edu/…, astronomers have made the first definitive detection of a radioactive molecule in interstellar space: a form, or isotopologue of aluminum monofluoride (26AlF). The new data – made with ALMA and the NOEMA radio telescopes – reveal that this molecule was ejected into space by the collision of two stars, a very rare cosmic event that was witnessed on Earth as a “new star,” or nova, in the year 1670.
In some stars, a thin layer of 26AlF (brown area in the 2nd image above) is formed around the helium core. A collision with another star can cause the dispersal of 26AlF into surrounding space.
This is the first molecule bearing an unstable radioisotope definitively detected outside of our solar system. The unstable isotope 26-aluminum (26Al) will eventually decay into the more stable element 26-magnesium (26Mg).
Iron and Titanium Detected in Atmosphere of distant Ultrahot Jupiter
Astronomers have detected Iron and Titanium in the atmosphere of the exoplanet KELT-9b, which belongs to a family called ultrahot Jupiters which orbit very close to their parent stars.
The exoplanet speeds around its host star, KELT-9 (aka HD 195689), in 36 hours at a distance only 1/30th that from Earth to the Sun. KELT-9b is tidally locked to the star, one side constantly bears the brunt of stellar radiation, and temperatures rise to 4,327 degrees Celsius, higher than the temperature of many stars.
Dr. Ehrenreich and colleagues at the Observatoire Astronomique de l’Université de Genève, Switzerland, observed KELT-9b as it transited in front of its host star. Analysis of the star light, as it filtered through the atmosphere of the exoplanet, revealed a strong signal for iron and titanium vapor.
These elements are difficult to detect in cooler exoplanets as they are sequestered in molecules or cloud particles, while on a hot cloud-free exoplanet like KELT-9b, they can exist solely in their atomic forms and can be detected using Earth based instruments.
Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst
OK, this last story is not about space molecules per se, but is about Gammy-Ray Bursts, extremely energetic radiation that last but a few seconds during a SuperNova explosion. This particular explosion was detected by NASA’s Neil Gehrels Swift Observatory on Dec 19, 2016; it left behind a black hole and belched an intense flash of gamma rays for a few seconds, followed by longer wavelengths of light including X-ray, visible light, and radio that continued to shine for week.
New observations of this region 2 billion light years away using the ALMA telescope in Chile, enabled the astronomers to produce the following fascinating time-lapse movie of the cosmic explosion, with a surprisingly long-lasting reverse shockwave from the explosion echoing back through the jets. See public.nrao.edu/… for more details.
The Atacama Large Millimeter/submillimeter Array (ALMA)
Many of these recent discoveries were made using the Atacama Large Millimeter/submillimeter Array (ALMA), located in the Atacama Desert of northern Chile at an elevation of 5,000 meters. It consists of 66 parabolic antennas with diameters of 12 m and 7 m, which observe radiation at millimeter and submillimeter wavelengths. The radio telescope combines signals from each antenna, working as an interferometer and a single giant telescope equal in size to the total array. The antennas can be moved across the desert plateau over distances from 150 m to 16 km, which gives ALMA a powerful variable "zoom" capability — larger distances between antennas provides narrower field and higher resolution.
Epilogue
These are but a small sample of molecules detected in stars and interstellar space. See en.wikipedia.org/… for a comprehensive “List of interstellar and circumstellar molecules.”
As Carl Sagan famously said, we are made of star stuff. The human body contains many elements heavier than Iron, such as Copper, Zinc, Molybdenum and Iodine, which are forged in Supernova explosions. A supernova explosion some 5 billion years ago resulted in the creation of the solar system, the planets, heavy elements, water, organic molecules, life, us. We now observe other stars, exoplanets and supernova through our telescopes and light analyzers, watching the cycle of life get kick-started on distant worlds, too far in space and time for us to interact with, yet.
Unfortunately, it is quite likely that we will all turn into molecular dust in a few thousand years and our atoms will get recycled in the next generation of life in the Universe. Even if we survive ourselves, the Sun will gobble up Earth in a few billion years. Will we move out and find ourselves a new home in a distant planetary system?
Makes you wonder what this hullabaloo is about race, color, gender, sexual orientation, religion and cultures.
References
- Astronomers observe cosmic steam jets and molecules galore — public.nrao.edu/…
- First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of Glycolaldehyde(HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS — arxiv.org/...
- Pair of Colliding Stars Spill Radioactive Molecules into Space — public.nrao.edu/…
- Astronomical detection of a radioactive molecule 26AlF in a remnant of an ancient explosion — arxiv.org/...
- Astronomers Find Iron and Titanium in Atmosphere of Ultrahot Jupiter — www.sci-news.com/…
- Atomic iron and titanium in the atmosphere of the exoplanet KELT-9b — www.nature.com/…
- Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst — public.nrao.edu/…
- First ALMA Light Curve Constraints Refreshed Reverse Shocks & Jets Magnetization in GRB 161219B — www.almaobservatory.org/...