Tag: Oumuamua

Astronomy News for September 2019.

There have been a couple of major discoveries in astronomy this past month, each in their own way teaching us something about the universe outside our solar system, and how similar that is to what goes on inside our solar system.

The first story concerns one of the now over 4,000 planets that have been discovered orbiting around other stars. Exoplanets the astronomers are calling them and most were discovered by the no longer functioning Kepler space telescope. (See posts of 16Dec2017, 28Apl2018 and 3Nov2019)

A chart detailing some of the discoveries made by the Kepler Space Telescope. (Credit: Sky and Telescope)

Most of the exoplanets that have been discovered to date are considerably larger than our Earth is, let’s be honest the bigger anything is the easier it is to see, and most have been found to be orbiting rather close to their parent star. Neither of these conditions is expected to make these exoplanets hospitable for life but the astronomers know that if they find enough exoplanets eventually they’ll start finding some that look more like Earth and which could be inhabited.

Our techniques for discovering exoplanets are far more likely to find big ones. This is a classification as of 2013. (Credit: Universe Today)

In fact their latest candidate possesses an Earth like feature never before seen in an alien world, water vapour in its atmosphere. The planet is officially known as K2-18b and it orbits around the small red dwarf star K2-18 that resides about 110 light years away in the constellation of Leo. Although K2-18b orbits closer to its star than the Earth does to the Sun because K2-18 is dimmer than our Sun the estimated temperature on K2-18b is between 0 and 40 degrees Celsius. That temperature is just right for water to exist on the planet’s surface and nearly perfect for life. Astronomers succeeded in detecting the water vapour in the planet’s atmosphere by studying the light coming from K2-18 as K2-18b was passing in front of the star. That light showed the characteristic absorption lines of water vapour.

An Artist’s impression of what the exoplanet K2-18b might look like. (Credit: ESA / Hubble)
When an element of Chemical Compound is heated they emit an emission spectra, top image is hydrogen’s. When light passes through the same material when cool it absorbs those same frequencies of light becoming an absorption spectra. (Credit: Physics Stack Exchange)

Before you start planning a visit to K2-18b however I should point out that the planet has a mass estimated at about eight times that of Earth and possesses a very thick atmosphere. Together these facts make the planet more like a warm version of Uranus or Neptune than our Earth. Additionally the planet’s star K2-18 is, like many small stars quite active with a large number of solar flares that might bath the planet’s surface in radiation. Still that thick atmosphere would give the planet’s surface some protection and if it does have oceans it is possible that life could exist there.

Astronomers will keep searching the stars of our galaxy looking for worlds that may possess life. Indeed the new James Webb Space Telescope that is expected to be launched in March of 2021 has been designed in part to carry out much more detailed studies of planets like K2-18b. So perhaps in just the next decade or so astronomers may finally discover a planet that truly is Earth like.

The James Webb Space Telescope is nearing completion and launch is expected in 2021. (Credit: Popular Science)

My second story concerns the recent observation of a comet like object that has entered our solar system from outside and is going to pass around the our Sun before heading back out into interstellar space. You may recall hearing about the first observed such an interstellar immigrant that was given the name Oumuamua a little more than a year ago. (See my post of 23May18).

The interstellar object named Oumuamua passed through our solar system in 2017. (Credit: Twitter)

Our new visitor was discovered on August 30th by Gennady Borisov of the Crimean Astrophysical Observatory and has been given the temporary designation of C/2019 Q4 (Borisov). The object has since been observed by more than a half dozen other observers and its orbital parameters have been tentatively determined with a result that the eccentricity of C/2019 Q4 is around 3.2. Now an object in a stable orbit has an eccentricity of between 0 and 1 so an eccentricity of 3.2 means that C/2019 Q4 will make one quick pass by our Sun and then head back out into interstellar space just as Oumuamua did back in 2017.

Unlike Oumaumau the interstellar object C/2019 Q4 (Borisov) has already show evidence that it is a comet. (Credit: Sci-News.com)

There are a couple of big differences between C/2019 Q4 and Oumuamua however. For one whereas all observations of Oumuamua indicated that it was a hard solid object, like an asteroid, C/2019 Q4 has already shown clear evidence of a comet’s tail. In other words Oumuamua was a rock while C/2019 Q4 is a dirty snowball.

The more important difference however may be that C/2019 Q4 has been discovered well before it passes the Sun and astronomers hope to have more than a year to study it.  Oumuamua on the other hand, was only discovered after it had passed the Sun and was on its way out of the solar system, leaving astronomers a little more than a month to observe it. Click on the link below to be taken to a YouTube video of the estimated track of C/2019 Q4 through our solar system. https://www.youtube.com/watch?v=vqMJo3DHOfg

I’m certain there will be a lot more to learn about C/2019 Q4 during the next year, and I hope they come up with a real name before long. You can be certain that I’ll keep you well informed about it. 

Astronomers declare Asteroid near Jupiter to be an Interstellar Immigrant.

It was only last October that astronomers discovered the first known interstellar visitor to our Solar System. (See my post of  4Nov17) The asteroid, which was discovered by the Panoramic Survey Telescope and Rapid Response System or Pan-STARRS telescope in Hawaii, was moving much too fast for the Sun’s gravity to keep it in a permanent orbit so it must have come from interstellar space and only spent a short period of time going around our Sun.

Astronomers named the asteroid Oumuamua, Hawaiian for scout, and we learned quite a lot about it in the few months Oumuamua was close enough to study. Astronomers found the composition of Oumuamua was like that of an iron-nickel meteorite than a dirty snowball like a comet. They also discovered that Oumuamua possessed a very unusual cigar shape being at least ten times longer than it was wide. The image below is an artist’s impression of Oumuamua.

The Interstellar Visitor Oumuamua (Credit: Space.com)

Now the astronomers at Pan-STARRS have discovered another asteroid that, while it is a permanent member of our Solar System, its orbit is so strange that it may not be an original member. Orbital simulations suggest that it could be an interstellar immigrant.

The new find hasn’t been given a name yet so I’ll be using its astronomical designation, which is 2015 BZ509. Now 2015 BZ509 orbits the Sun with a semi-major axis (Average distance) only slightly less than that of Jupiter. The most unusual thing about its orbit however is that 2015 BZ509 orbits in the opposite direction of nearly every other object in the Solar System. It has what is called retrograde motion. The image below shows a telescopic view of 2015 BZ509, it’s in the yellow circle.

Two pictures of the Asteroid 2015 BZ509, in yellow circle (Credit: Los Angeles Times)

To understand what retrograde means let’s imagine ourselves looking down on the Solar System from the Sun’s north pole (which happens to correspond to Earth’s north pole). Looking at the image below of the inner Solar System ( the whole thing is too big to really illustrate my point), the orbits of the planets, the spin of the Sun and the spins of all of the planets, even the motions of the major moons all go counterclockwise. The reason for this is simple; the original gas and dust cloud that formed our Solar System must have had a counterclockwise spin and so the Sun, the planets and all of the moons shared that counterclockwise motion.

The Inner Solar System (Credit: University of Rochester)

Objects that orbit in a clockwise motion are very rare, but not completely unknown. There is an entire class of objects known as Centaurs who orbit the Sun between the orbits of the gas giant planets (Jupiter, Saturn, Uranus and Neptune). This small number of asteroids are of great interest to astronomers simply because of their unusual orbits and astronomers have done an enormous amount of computer modeling trying to understand how those asteroids got those orbits. What they found was that the powerful gravity of the gas giants could capture an object out of the Ort cloud and an object so captured could on occasion wind up going the wrong way. Astronomers also found that such orbits are unstable, lasting less than 100 million years. The image below shows a few of the crazy orbits of the Centaur asteroids.

Centaur asteroid Orbits (Credit: Nick Fiorenza, Lunar Planner.com)

2015 BZ509 isn’t a Centaur however, it’s not between two gas giants its in an orbit very similar to Jupiter’s only backward. And when researchers F. Namouni of the Universite Cote d’Azur in Nice France and M. H. M. Morais of the Universidade Estadual Paulista in Sao Paulo Brazil carried out one million simulations of the orbit of 2015 BZ509 they found that its orbit was stable going back to the very beginning of our Solar System four and a half billion years ago.

So if 2015 BZ509 has been sitting around Jupiter pretty much since the formation of Jupiter and the other planets how did it get its backwards orbit. Doctors Namouni and Morais theorize that, back when the Solar System was very young and we were a part of a star cluster like the Pleiades or the Orion nebula 2015 BZ509 could have been grabbed from another star system that was also in the process of formation.

Personally I think that claiming that 2015 BZ509 is interstellar in origin just because it has a very unusual, but nevertheless stable orbit is a bit of a stretch. I want to see some more evidence, and I expect I’ll get my wish as astronomers continue to study this fascinating object.

P.S. Orbital dynamics isn’t my forte but I do know how to calculate the difference between the specific energy of an object (that’s the energy per kilogram of mass) between being free of the Sun’s gravity and being captured at Jupiter’s orbit. I calculate that 2015 BZ509 would have to have somehow lost 85 million Joules of energy for every kilogram of its mass if it is an interstellar immigrant. That’s lot so you can see why I’m more than a little doubtful!

 

Have Scientists taken a critical step in understanding the Chemistry of how life began and an update on our Interstellar Visitor.

Ever since Charles Darwin’s ‘On the Origin of Species’ had demonstrated that all of the multiform types of living creatures here on Earth had evolved over millions of years from a single primitive type of life scientists have sought to understand how that first living thing came into being. Much has been learned in the last 150 years but many of the details of the chemistry involved in the development of a complex, self-replicating molecular system, i.e. a simple living cell, are still unknown.

Now researchers at The Scripps Research Institute (TSRI) have published a paper in which they claim to have found a chemical compound that played a key role in assembling short nucleotide chains (early genetic material) with peptide chains (short version of proteins) encapsulated in a lipid vesicles (early cell walls). Finding a catalyst that could combine these three distinct types of chemicals, and which could have existed on the primitive Earth has been a goal of ‘Origins of Life’ researchers for the past several decades.

The scientists at Scripps have given their compound the name diamidophosphate or DAP for short and have published their results in the journal ‘Nature Chemistry’. The figure below shows the chemical diagram and the structure of DAP.

Chemical Formula for DAP (Credit: Ramanarayanan Kirshnamurthy)

Structure of DAP (Credit: Ramanarayanan Krishnamurthy)

According to lead researcher Doctor Ramanarayanan Krishnamurthy DAP “would have allowed other chemistries that were not possible before, potentially leading to the first simple, cell based living entities.” “With DAP and water and these mild conditions, you can get these three important classes of pre-biological molecules to come together and be transformed, creating the opportunity for them to interact together, ” Krishnamurthy said. The image below shows DAP and the three classes of chemicals needed to build a simple cell.

DAP linking three classes of pre-biological complex compounds (Credit: Ramanarayanan Krishnamurthy)

Whether or not DAP was THE chemical catalyst that enabled the formation of the first living cell will be difficult to prove four billion years after the fact but Dr. Krishnamurthy and his co-authors intend to continue their study of DAP and other phosphorylating compounds. If you’d like to read the press release put out by the Scripps Institute click on the link below.

https://www.scripps.edu/news/press/2017/20171106krishnamurthy.html

Before I go I’d like to take a moment to update one of my posts of just last week (4Nov17) about the interstellar visitor that entered our solar system and is now on its way back into the void between the stars. Well A/2017 U1 has been given the new name of 1I Oumuamua. The 1I indicates that it is the first interstellar object ever discovered while Oumuamua is a Hawaiian word meaning scout or Messenger. 1I Oumuamua was discovered by the Pan-STARRS telescope in Hawaii after all. The image below shows Oumuamua’s path through our solar system.

Path of 1I Oumuamua through our Solar System (Credit: NASA-JPL-Caltech)

 

More importantly a group of Astronomers are preparing a paper in which they give their estimate as to the place of origin of Oumuamua along with how long it took to reach our solar system. Working backward along the trajectory of Oumuamua Eric Gaidos and Jonathan P. Williams of the University of Hawaii along with Adam Kraus of the University of Texas are of the opinion that Oumuamua originated in the Carina and Columba Associations, clusters of young stars at a distance of 215 to 365 light years. (Carina and Columba are constellations in the southern sky).

Current research estimates that the Carina and Columba Associations were an active star-forming region about 45 million years ago. If Oumuamua had been thrown out of a newly forming solar system in the direction of our Sun at a velocity of 1-2 kilometers per second it could just now be arriving in our solar system!

Even though Oumuamua was only near enough for us to study it for about a month we have already learned a great deal from it. This is only the start, in the years to come I have no doubt that we’ll be learning a great deal more.