Space Sunday: alien worlds, telescopes and lightsails

An artist’s impression of the Teegarden’s Star planetary system might look like when observing it from the “far side” relative to our own Sun (shown in the background and inset). Credit: University of Göttingen

Two Earth-sized planets have been found orbiting a star 12.5 light-years from our own, adding to the catalogue of exoplanets located in our own cosmic back yard.

The star in question is Teegarden’s Star, a M-type red dwarf, the most common type of star in our galaxy, and therefore the most frequent type found to have planets and planetary systems. However, Teegarden’s Star is a little different to other red dwarfs we’ve observed with or without planets. For a start, despite being only a short cosmic stone’s throw from Earth, it is incredibly dim – so dim that we didn’t even notice it until 2003. Not that that in itself is usual, it’s believed that the space around us for a distance of about 20 light years could have many dim red dwarf stars hiding within it, simply because this region of our galaxy seems to have a much lower density of such stars than we see elsewhere.

What makes Teegarden’s Star odd in this respect is that it wasn’t found as a result of a search for such nearby dim red dwarfs, but because astronomers tripped over it whilst reviewing data originally gathered in the 1990s by the Near-Earth Asteroid Tracking (NEAT) project. In fact, the star is actually named for the head of the review team, Bonnard J. Teegarden, an astrophysicist at NASA‘s Goddard Space Flight Centre. The star is also somewhat unusual in that it has a large proper motion (approximately 5 arcseconds per year), marking it as one of seven stars with such large proper motions currently known.

Observations of the star made in 2010 by the Red Optical Planet Survey (ROPS) suggested the star might have at least one planet orbiting it, but the data was insufficient to draw a definitive conclusion. However, in June 2019, and after three years of verifying their data, scientists conducting the CARMENES survey at the Calar Alto Observatory announced evidence of two Earth-mass exoplanets orbiting the star within its habitable zone.

A star and its planet moving around a common centre of mass. Credit: wikipedia / “Zhatt”

The planets were detected using the radial velocity method (aka Doppler spectroscopy), also informally referred to as the “wobble method”. Putting it simply, a star with planets doesn’t simply spin on its axis with the planets whizzing around it. Rather, the mass of the planet(s) works against the mass of the star, creating a common centre of mass which, although still inside the star, is sufficiently removed from its own centre to cause the star to effectively rolls around it (see the image on the right).

This means that when seen from Earth, there are times when the star can seem as if it is moving “away” from our telescopes, signified by its light shifting to the red end of the spectrum. Equally, there are other times when it appears to be moving “towards” us, signified by its light shifting to the blue end of the spectrum. It is by observing and measuring this visible Doppler shift that tells us there are planets present. In all, this method of stellar observation has accounted for almost one-third of all exoplanets found to date.

The key point with this method of observation is not only does it allow astronomers to locate planets orbiting other stars, it actually allows maths to be applied, allowing the number of potential planets to be discerned, their distance from their parent star and important factors such as their probable mass, which in turn allows their likely size and composition to be estimated.

In the case of Teegarden’s Star, the data indicates the two planets orbiting the star – called Teegarden’s b and Teegarden’s c respectively – have a mass of around 1.05 and 1.1 that of Earth each, suggesting they are probably around the same size as one another and comparable to Earth in size. Teegarden’s b, the innermost planet, orbits its parent every 4.9 terrestrial days, and Teegarden’s c every 11.4 terrestrial days.

An artist’s impression of the Teegarden’s Star system, as seen from “above”. Credit: University of Göttingen

The combined mass of these planets, coupled with the amount of Doppler shift exhibited by Teegarden’s Star has led to some speculation there may be other, larger planets orbiting much further out from the star. Such planets would be hard to locate because Teegarden’s Star is so dim when observed from Earth, astronomers cannot rely on the transit method  – where large planets passing in front of their parent star can cause regular dips in its apparent brightness – to identify their existence.

However, what is particularly interesting about Teegarden’s b and c is their location relative to their parent, and the nature of Teegarden’s Star itself. The latter is a particularly cool and low-mass red dwarf, with just one-tenth of the Sun’s mass and a surface temperature of 2,700°C (4890°F). This means that at their respective distances, both planets are within the star’s habitable zone – and may well have atmospheres.

The two planets resemble the inner planets of our solar system. They are only slightly heavier than Earth and are located in the so-called habitable zone, where water can be present in liquid form.

– Mathias Zechmeister, University of Göttingen, Teegarden planetary team lead

This latter point  – the existence of atmospheres around both planets – has yet to be proven. As noted previously in these articles, M-type stars are actually not nice places; when active (and Teegarden does seem to be well past its active stage) in their youth, they can be prone to violent irradiative outbursts which could both strip away the atmospheres of any planets orbiting them over time and irradiate the planets’ surfaces. And even if  the planets do have atmospheres, their close proximity to their parent likely means they are both tidally locked with their same face towards it. This is liable to make them pretty inhospitable places and potentially prone to extremes of weather.

But there is one other interesting point to note here. While Teegarden’s Star may well be dim to the point of being practically invisible when viewed from Earth, the same isn’t true the other way around: our Sun would be a bright star in the skies over Teegarden’s b and c. What’s more, the angle of our solar system to those worlds (practically edge-on) means that if we were to imagine one of them having an intelligent, scientific race, they could easily detect the planets orbiting our Sun using the transit method of observation, and could probably deduce up to three of the innermost planets might be capable of supporting life.

Continue reading “Space Sunday: alien worlds, telescopes and lightsails”

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A Slavic Rebirth in Second Life

Slavic Rebirth: Art Gallery

Currently open through until July 20th is a celebration of pre-Christian Russia entitled Slavic Rebirth, the opening of which was intentional timed to coincide with the summer solstice. I  was alerted to the event by ViktorSavior, who will also be presenting his art at the event, combined with the poetry of AlenaPit.

Occupying floating islands bearing builds by Arin Bellios that float high above Isles of Devotion, the Full region held by Djembe Dragonfire and Jay Abernathy, who have donated the space to the event free of charge, Slavic Rebirth is a multi-faceted event featuring art, music, workshops, a fashion show, and a market. The organisers describe the event thus:

This is the world BEFORE the arrival of Christianity in the Russian lands. This is paganism in its best  manifestation, unity with nature and native gods. This is the strength of the spirit, purity of thoughts, the beauty of the body, the awareness of walking the right path. This is a world of fairy tales and epics. This is our ancient memory that you need to wake up and open your eyes.

There are a number of landing points associated with the event, but I’m focusing on the art gallery area here, as this is what particularly drew me to the event.

Slavic Heaven: the location alongside the gallery where music events will be held and where people can relax

Occupying a large central island that is linked to, and within eyesight of, two small event spaces, the gallery is open-air, but has a strong element of what might be regarded as classic Russian architecture which, despite the pre-Christian focus of the event, perhaps carried echoes of a church-like structure.

The art is displayed within the open arches of the tiered walls and is actually deceptive: what at first glance appears to be the works of a single artist is in fact three (or four, once Viktor’s art is added!) individual switchable displays of art: a board close to the landing point allows visitors to select which of the  artists’ work is on display. Allowing for the addition of Viktor’s art, the three artists currently on display are:

  • Roman Papsuev (aka Amok): a contemporary Russian artist who may be known to some for his work depicting scenes and individuals from George R.R. Martin’s A Song of Ice and Fire books (note not the TV series Games of Thrones, so don’t expect images of Kit Harrington or Emily Clarke, etc). The pieces presented in Slavic Rebirth are from his collection Tales of Old Rus’, featuring line drawings presented in monochrome.
Slavic Rebirth: Roman Papsuev
  • Vsevolod Borisovich Ivanov: another contemporary Russian artist inspired by the traditions and history of Russia – particularly that of medieval Russia, and pagan mythologies of old Russia. His paintings are rich in colour and content, covering a wide range of subjects: heroes, gods, creatures, architecture and the harsh beauty of old Russia.
  • Viktor Anatolyevich Korol’kov: a classically trained artist whose work has encompassed the history and myths of Europe (Germany, Scandinavia, Italy, Greece), Egypt, the books of the Bible and more. All of this led him to a fascination with Slavic history, art and mythology – which led him to the main thrust of his art, as seen in Slavic Rebirth, a celebration of that old history, presented here under the title Enchanted by Old Rus’.
Slavic Rebirth: Vsevolod Borisovich Ivanov

When switching between the artists via the control board, the art on display on the two sides of the gallery will change in unison, as will the exhibition title board on display (each of which offers a profile of each of the artists. How well this might would with multiple people viewing the art might require some coordination to prevent conflicting changes, but the approach is interesting. Note, as well, that touching individual pieces of art will deliver a note card to you, offering information on the art itself.

Throughout the month of the event there will be a number of musical performances taking place at the Slavic Heaven floating island to the south of the art gallery (use the touch-to-teleport portal at that end of the gallery to reach it). These include:  Italian SL singer Malesh, who will be appearing at 13:00 SLT on both Tuesday, June 25th and DJ Dalilu who will be appearing at 12:00 noon on Wednesday, June 26th.

Slavic Rebirth: Viktor Anatolyevich Korol’kov

Also to be found via the teleport arch at the north end of the art gallery (and closest to the landing point) is the Slavic market built around an ancient temple of Goddess Lada.

The final part of the event spaces for Slavic Rebirth is the Seasons Island. Offering ” all seasons of Russian nature”, this is the focus of a photo exhibition that forms part of the event – details from the event information boards – and for the Slavic Rebirth Fashion Show and Contest that will be taking place on Friday, June 28th at 12:00 noon. The theme for this is Slavic history and fairy-tales, and members of the public can participate; again, details are available at the event spaces, and there are two workshops / rehearsals for those interested in joining in: Sunday June 23rd at 10:00 (so very short notice here!) and Monday, June 24th, at 11:00 SLT.

Slavic Rebirth: Seasons Island

Further activities taking place at Slavic Rebirth will, I believe, be posted through the event spaces. In the meantime, here’s the full set of SLurl for this event.

SLurl Details

Isles of Devotion is rated Adult