TGT #30 - The Rare A-Star With A Planet; + 5 more [Aug. 15, 2022]
This Just In--Making O2 on Mars, Ryugu's Origin, Rare A-Star World, Proving Late Bombardment; Deeper Looks--Parker & ELT Updates; Sky Planning Calendar--Giants In, Inner Worlds Out, Taurus' 2 Red Eyes
Cover Photo - The Rare A-Star With a Planet
In This Issue:
Cover Photo — The Rare A-Star With A Planet
Welcome to Issue 30!
This Just In —
* Mars Explorers! Need Oxygen? Zap!
* Where Did Ryugu Come From?
* A-stars and Exoplanets - The Two Rarely Meet, Why? Have We Found The Exception? (Cover Story)
* The Oldest Part of Earth Caused by Cosmic Impacts
Deeper Looks —
* EAS: Updates on Missions and Observatories
Sky Planning Calendar —
* Moon-Gazing - Four Weeks of Sky
* Observing—Plan-et -
- Inner Planets Leave the Sky
- Gas Giants Create the Evening Show
- Mars Makes Taurus Have Two Red Eyes
* Border Crossings - Virgo Ain’t Lion….
Astronomy in Everyday Life — Scientific Cereal
The Classroom Astronomer Newsletter-Inbox Magazine #34, August 15, 2022 Issue Highlights.
Welcome to The Galactic Times Newsletter-Inbox Magazine #30 !
With planets entering the evening sky for observations (and Saturn being the, um, star of the show), planetary news is the thing this issue.
Elon Musk may THINK he is going to get people to Mars PDQ but how are they going to survive there? Here is a way to get them a continual supply of oxygen—zap the atmosphere with plasma!
How about we look into the distant past? What was the early solar system like? The surface particles of the asteroid Ryugu that were returned from space seem to suggest that our water may have come from asteroids from deep space.
And our continents cores were formed by the end of the Late Heavy Bombardment, about 3+ billion years ago. Evidence for that is seen on every hard planet and moon in the solar system except Earth…until now.
And why don’t we seen planets around hot blue stars much? Partly because maybe their atmospheres get blown away and they are just too small to detect, but we found one that might have managed to hold on to its air.
Meanwhile, the latest on the Parker Solar Probe that touches the Sun for the first time ever, and updates on the construction of the biggest telescope being built on Earth.
In the sky, inner planets are disappearing from view, but the gas giants are taking center stage. Mars, usually compared to summer star Antares, gives you a different star to compare it to, Aldebaran, giving Taurus two red eyes. The Bull must be staying up too late too often….
Yours truly is taking a bit of a vacation. First one since, well, before Issue #1, over 16 months ago. It won’t be a complete vacay. There are possibly two conferences I might attend—there are still uncertainties there, even this close! Sheesh—and I might sit back and just do some writing on books, but overall I need to turn the laptop off a while. The Galactic Times and The Classroom Astronomer each are over 3000 words a piece and that’s a lot of monthly writing. So I’m giving you all a month of Sky Planning info here beyond the normal news and commentary.
Enjoy while I rest my eyes and fingers.
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This Just In
* Mars Explorers! Need Oxygen? Zap!
Martian explorers need to bring a lot of stuff, but ultimately they are going to have to produce what they need to survive using native materials. One of those things is breathable air. Mars’ atmosphere is made nearly 95% of carbon dioxide, at a pressure that is near just 4% of Earth’s atmosphere, the latter being 78% nitrogen, about 21% oxygen, and traces of other gases. So where are you going to get fresh air? According to scientists reporting in the Journal of Applied Physics, from Martian air! Say what?
This international team of researchers has presented a method of producing oxygen from carbon dioxide gas by zapping it was plasmas, high energy streams of electrons. The carbon dioxide molecules decompose into lots of oxygen atoms. These atoms can then be collected to be used for breathing, or for fertilizers or fuels. While Earth’s atmosphere does not have as high a percentage of carbon dioxide as Mars, its growing amount is clearly contributing to climate change, and the plasma process could perhaps also be a way to cut down CO2 production at the start and releasing O2 into the air after manufacturing processes instead of CO2 as a waste product.
* Where Did Ryugu Come From?
An article in Nature Astronomy discusses the composition of the material brought back to Earth by the Hayabusa2 mission to the asteroid Ryugu. The probe landed twice on the little asteroid in 2019 and took samples. One was a surface collection, the other from material a bit inside because an impactor made a small crater which Hayabusa could explore. The samples were sealed against contamination and returned to Earth, and later analyzed and compared to organic rich C-type asteroids and carbonaceous chondritic meteorites. C-type asteroids are considered the best prospects for the source of Earth’s water, and the meteorites the delivery system. But the meteorites are not pristine because of contamination with terrestrial environment.
Ryugu seems to be the most uncontaminated material available for laboratory study and “best proxy we have for the bulk composition of the Solar System,” the authors state, more than the meteorites that arrived on Earth. It is consistent with an outer Solar System origin, i.e. in the realm of the comets.
* A-stars and Exoplanets - The Two Rarely Meet, Why? Have We Found The Exception? (Cover Story)
If you do a statistical survey of all the stars and the exoplanets known to be around them, you will note two facts: first, most of the stars are stars cooler than the Sun and rarely hotter by much, and second, most planets found are far larger than the Earth, in fact, most are Jupiter-sized or larger. Why don’t we see exoplanets around hotter stars?
The primary reasons are our detection methods. Most are found using transits of the exoplanets around the star, and those have to be orbiting quick enough for us to find them, and big enough to make an impression in the light curve. Small planets are lost in the light curve noise. Slow orbiters are far from the star and missed. Last, hot stars like Vega, an A-star, are much rarer than solar-type G-stars.
So when Berkeley astronomer Courtney Dressing and graduate student Steven Giacalone found a planetary transit in star HD 56414’s data using the TESS satellite, and then found that a spectrum of the star indicated it was a young, 400+ million-year-old A-star (see Cover Photo), they tried to figure out why the planet could even be there. The planet orbits the star every 29 days and has a mass about that of Neptune (not quite 4 Earth masses). So how come it is there and we can find it? A-stars have high temperatures and fast solar winds and should blast Jovian planet atmospheres into space.
Dressing and Giacalone speculate that the planet is actually far enough and massive enough to be able to hold onto its ‘warm’ atmosphere, but if it were closer, its inner core would be all that would be left and that would be too small to detect. This could mean that, since it is assumed that all stars form with planets, many hotter stars would have lots of Neptunian cores orbiting them with their atmospheres ripped away from the closer worlds being, well, too close. “We might expect to see a pileup of remnant Neptunian cores at short orbital periods” around such stars, the researchers concluded in their Astrophysical Journal Letters paper, online version August 12, 2022. If only we had a means to detect them….
* The Oldest Part of Earth Came From Cosmic Impacts
You know that the Earth’s surface is ever changing, building up, eroding down. But somewhere there is an oldest part, a piece of a continent that is as old as it gets. An international team, headed by Tim Johnson of Curtin University, Australia, thinks they have found it, and it was formed with the help of giant impacts from space.
The Earth reached solidity slowly, beginning 4 billion years ago and taking 1.5 billion years to happen. Many of the oldest continent rock samples show they were under water and made from basaltics. Continents, like many things, started small, as cratons, and merged into the more stable larger continents we have today. But what formed, or allowed to form, those cratons, when the early Earth was getting continuously smashed up in the Heavy Bombardment periods? They should have been broken up before they had a chance to grow. The records for that end in the time period 3.9 to 3.5 billion years ago (3.5 Ga), a time when cratons first appeared. Is that a coincidence?
In Australia is the Pilbara Craton, among the oldest and best exposed continental fragments on Earth. Its rocks range from 3.6 to 2.9 Ga. In a nutshell, the geologists found that it was built in three stages, evidenced by changes in Oxygen-18 counts in Zircon minerals, all evidence for impacts that shattered and rebuilt the craton, at times of 3.6, 3.4-3.0 and some time after 3.0, Ga. Thus, the craton shows the evidence to prove the Earth suffered through the same Late Heavy Bombardment seen on the Moon and elsewhere, and where in time it ended, and it helped to form the continents upon which life would eventually take root, once the Bombardment ended.
As the article concluded, “The search for evidence of the Late Heavy Bombardment on Earth has been a long one. However, all along it seems that the evidence was right beneath our feet.”
EAS: Some Updates on Missions and Observatories
Parker Solar Probe
Dr. Javier Rodríguez-Pacheco of the University of Alcal´a, Spain, brought European astronomers up to date on the achievements of the Parker Solar Probe, known as the mission that ‘touches the Sun.’ Launched in 2018, the PSP orbits the Sun in a very elongated polar orbit that takes it increasingly closer to the Sun’s surface each time and then way out to Venus’ distance. It has done at least five different major investigations so far, and has several research questions to answer.
Among the latter are: How and Where does the solar wind plasma and magnetic field originate, and what heats the Corona to over 1 million degrees (the solar surface is merely 6000 degrees Kelvin!)? Another is how does the Sun create and modulate the heliosphere—-that bubble in which all the bodies of the solar system reside safely from interstellar effects? And how do solar eruptions fill the heliosphere with radiation particles? And there are others.
The Parker Solar Probe measures solar wind plasma, energetic particles that it encounters, and various fields and waves that hit it. Remotely it observes the Sun in visible, X-ray and ultraviolet light, including its not-seen-from-Earth polar regions. It also does imaging and spectroscopy and reads the magnetic fields, and images the corona and heliosphere. It takes up to a half year to do an orbit and expects to function from 4 to 7.5 years.
Though the Sun’s photosphere, its nominal surface, is about 430,000 miles from its center, Parker is considered to be touching the Sun when it is 4,000,000 miles above the photosphere, inside the Corona. Eventually, it will close in and orbit the Sun in about 90 days, making 24 encounters before its mission ends.
One of the discoveries it made is called solar “campfires.” They may be what helps bring heat from the photosphere, which they are just above, to the corona. They are almost always between two magnetic features, often of opposite polarities of some sort.
Other items viewed were planetary in origin. A dust ring around Venus and that planet’s weak magnetosphere. And recent Comet Leonard’s tail.
The ELT (Extremely Large Telescope)
Dubbed the World’s Largest Eye on the Sky (http://elt.eso.org), the ELT is under construction. It is made up of a mirror with 798 segments! It will be able to take photographs from Earth at greater than 10 times the resolution of the Hubble Space Telescope.
The ground site is almost complete, and it will be entirely energy independent.
Sky Planning Calendar
Moon passages by a star, planet or deep sky object are a good way to find a planet or other object if you’ve never located it before.
August 18 Uranus lies 0.6-degrees from the Moon during daylight hours. And during that time, if you are in Hawaii, Alaska, northern US states, or Canada, and you have a telescope, you can watch the Moon pass over the distant world. If not, during this dawn, the outline of the near-First Quarter Moon is like a bow with an arrow in it, the imaginary tip one Moon diameter away to the left, on top of Uranus.
August 19 Last Quarter. Officially, just after midnight. Nearby will be red Mars, the Moon closing to 3 degrees of it. Find the Moon between Mars and the Pleiades star cluster.
August 22 Apogee. A Micro-Waning Gibbous Moon.
August 25/26 The Moon passes 4-degrees north of Venus, if you are in Asia. In the USA, you’ll find the Moon above Venus in the dawn the first date, below left on the second date.
August 27 New Moon.
August 28-31 If your West horizon is really clear to the ground, and it is clear about 30 minutes after sunset on the 28th, you can see the 1-day-old thin crescent Moon slightly north of west, and 10-degrees to the right of very bright Mercury! Not the planet’s best northern hemisphere appearance, but Mercury is moderately bright. If both are too difficult tonight try tomorrow, the 29th, when the 2-day-old Moon is directly above the planet and you can drop a line to the horizon to find it. Binoculars can help both nights. On the 30th, a line from the now-fatter and easier to find crescent Moon through the star Spica will also reach Mercury near the horizon.
September 3 First Quarter.
September 7 Perigee. A Super-Waxing Gibbous Moon!
September 9 Saturn is 4-degrees north of the Moon.
September 10 Full Moon.
September 11 Jupiter is just under 2-degrees north of the Moon.
September 14 And we return to whence we started….Uranus is once again buddy-buddy with the Moon, and occulted for observers in Europe, the Middle East, Russia and northwest Alaska, what might be the coolest (at least temperature-wise) spot in the United States).
In this issue, because of the four-weeks time frame, this column will cover the Solar System by zone.
Mercury and Venus are in view, but not well and/or not for long.
Mercury is in the evening and it is best seen….if you live south of the Equator. For those to the North, it starts out setting barely an hour after Sunset. It reaches its Greatest Elongation from the Sun on August 27th but it was much more brilliant earlier in the month and is fading in +0.x magnitude ranges now, which is not that easy low in bright twilit skies. As mentioned in the highlighted section above, it will be easiest (though challenging enough) to see from the 28th to 31st with the very thin young crescent moons as guides. On the 5th of September Mercury sets no later than 45 minutes after the Sun, and if you have any horizon obstacles, you probably will have lost it from view a week earlier than that.
Venus, on the other hand, Queen of the Dawn still, starts out rising just after morning twilight begins but that interval is steadily shrinking. By just after our mid-September calendar ends, it rises only about 40 minutes before sunrise, and it disappears into the solar glare before the month ends.
On the 4th and 5th of September Venus passes close to first magnitude star Regulus, its last dawn conjunction of note. Venus does pass rising Mercury late in September after our calendar ends, but that’s be a tough conjunction to view.
So we start with two inner planets in view and end with none.
Outer Gas Worlds
Working our way inwards, Saturn jump starts the evening, rising before the Sun even sets. Enjoy the view of the rings at their maximum size, and Titan, its brightest moon, shuttling from one side to the other reaching its maximum distances even far enough that small cheap store-bought scopes can see it. Not sure where Saturn is? Look for the brightest star rising in the East during twilight, and find it near the Moon on September 8th. Watch its retrograde (backwards, westward) motion by comparing it to the nearest “bright” star, Iota Capricorni, where Saturn starts the month 2.5-degrees from the star, and ends 1-degree away. Saturn is up all the way through to dawn twilight, until September 2nd when it sets when morning twilight starts.
Jupiter is joining the evening show. It rises at the end of evening twilight on the 19th of August. With only Venus and the Moon brighter than Jupiter at night, you can’t fail to recognize it once it is in the sky. Still not sure? The Moon passes by on the 11th. In late September will be in opposition to the Sun, as Saturn just was, and up to party all night.
Uranus, technically a naked eye world, lies east of Jupiter and is noteworthy right now as the planet getting covered up by the Moon every darn month, and twice in this Sky Calendar!
We’re not dealing with Neptune right now, though it too is about to reach opposition. It is faint and nothing happens with it.
So the evening sky is a…gas. <groan>
And then there is Mars—an Outer World, but a terrestrial one, not a gas giant. It will reach opposition a short few months after Jupiter. Right now it rises at midnight Daylight Saving Time on August 16th and earlier each succeeding night so has become technically an evening world like all the other worlds save Venus. It also is becoming more prominent—it crosses the positive/negative magnitude border on August 21st. Venus and Jupiter are always bright with negative magnitude values. Mercury and, rarely, Saturn, can be negative, too. At close oppositions, Mars can be a blazing red. For the rest of the year, that will be Mars’ description.
An interesting thing to see about Mars, late at night or during your pre-sunrise walk, when it is most cool in temperature—-Taurus will have TWO RED EYES! The nights of September 8-9 will see Mars about 4 degrees from Aldebaran, the bright red ‘eye’ of Taurus the Bull. Aldebaran is on the eastern end of the “V” of the Hyades star cluster that makes up the face of Taurus. Mars will mark the western eye, mimicking Aldebaran but about a magnitude brighter. What will be interesting will be to see which ‘star’ is more red! An interesting photographic exercise, too.
Peaceful coexistence…until August 23rd. The Sun is in Leo, astronomically and astrologically. Then, horoscopes flip over to Virgo. But Leo has a lot of Ecliptic territory, and Sun stays in the Lion until the 15th of September, when this Sky Calendar ends.
Astronomy in Everyday Life
As least, for once, the title has the science right….
The Classroom Astronomer Newsletter-Inbox Magazine #34, August 15, 2022 Issue Highlights
Cover Photo - Two Red Eyes for a Bull
Welcome to Issue 34!
Sky Lessons -
- Very Young Moons and Tiny Planet
- No Bull Here, Just Mars and a Red Star
The RAP Sheet -
- Science Cafés: Exploring Adults’ Motivation to Learn Science in a Community Space
- Sonification and Sound Design for Astronomy Research, Education and Public Engagement.
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