In the show this time, we talk to Connor Smith about searching for blobs in the submillimetre regime, Fiona Porter rounds up the latest news, and we find out what we can see in the November night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.
This month in the news: a historic spacewalk, a water-carrying visitor passes by, and a new method of detecting black holes
To start us off, the first all-female spacewalk has been completed. On the 18th of October, Christina Koch and Jessica Meir, both NASA astronauts, made a spacewalk to perform repairs on the International Space Station. (Note that the audio mistakenly says this took place on the 16th.)
The spacewalk lasted about five and a half hours, and during their excursion the astronauts removed and replaced a faulty battery on the ISS. This is routine maintenance for the space station, and it's hoped that eventually all-female spacewalks will be just as routine. For now, though, it's still very imbalanced – before this, only 14 women had performed spacewalks, compared to 213 men.
It was originally planned that an all-female spacewalk would be completed in March, but this fell through as only one medium-sized spacesuit was available at the time, and it was postponed for safety reasons. Now, however, NASA are working on making their next generation of spacesuits more modular, making them better able to be worn by astronauts of all shapes and sizes. These are being prepared for the Artemis programme, which hopes to put the next man and first women ever on the Moon by 2024.
Next, an interstellar visitor has been passing through our solar system and looks to be carrying water. Comet 2I/Borisov is the second known interstellar object we've spotted in the solar system after ‘Oumuamua, which has been discussed in past episodes. Borisov is of particular interest as the path it's travelling shows it must have originated from deep space, allowing us to see how its properties compare to comets from within the solar system.
Recently it's been noticed that Borisov is showing oxygen in its spectrum, the mostly likely source for which is water breaking down into its constituent hydrogen and oxygen. While this isn't surprising – comets quite frequently carry water – this does make it the first source of interstellar water we've observed, and could provide insight into how water travels in space.
Of particular note is that Borisov also shows cyanide in its spectrum, like solar system comets, and the ratio of water to cyanide has been established to be very similar between the two – it seems despite its far-off origins, so far Borisov isn't that different from the comets we've seen before. Borisov will reach its closest approach to the Sun on around the 8th of December, and is expected to remain visible until at least September 2020, so there's still time yet to find out more.
Finally, a new method of looking for black holes has found its first candidate. Typically, black holes have been identified by observing stars orbiting around them, like the supermassive black hole Sagittarius A*, or more recently, spotting merging with another black hole by LIGO detecting their gravitational waves. This, however, biases the search, as more massive black holes are easier to detect this way than less massive ones.
The new method relies on the fact that it's relatively common for stars to be in binary systems, with two stars orbiting each other. If one of the stars dies and becomes a black hole, it and its companion star still orbit each other, but the black hole no longer emits light. By tracking the change in an apparently single star's emission spectrum, it's possible to identify if it has an invisible black hole companion, as the star's light will be Doppler shifted as it orbits around the black hole.
Recently, this method has identified its first black hole, and in doing so has shown it can find an entirely new class of black hole – low-mass black holes. The detected black hole is only 3.3 solar masses, far less than typical stellar black holes – which tend to be between 10 and 100 solar masses – or those detected by LIGO, which have a typical mass of around 20 solar masses. This is actually quite close to the lower mass limit possible for black holes, which is believed to be between two and three solar masses – any lower than that and a dying star can't collapse into a black hole, and instead becomes a neutron star. Using this method to identify more low-mass black holes will therefore open up an entirely new population to study, and might give us more insight into what happens at the boundary between black hole and neutron star. The paper for this discovery can be found here.
Interview with Connor Smith
We speak to Connor Smith, a PhD student from the University of Cardiff, about his research into "blobs" detected in submillimetre wavelengths by ALMA. These "blobs" are actually individual galaxies existing as part of galaxy clusters, and by studying them over a range of look-back times, their evolutionary history can be traced.
The Night Sky
Ian Morison tells us what we can see in the Northern Hemisphere night sky during November 2019.
- Jupiter, shining on the 1st at magnitude -1.9 and falling to -1.8 during the month, can be seen very low in the southwest as darkness falls. As the month progresses, its angular size drops from 33.4 to 32.1 arc seconds - but, by the end of the month, will be lost in the Sun's glare. Jupiter lies in the southeastern part of Ophiuchus and is heading towards the southernmost part of the ecliptic so, as it appears in the twilight, will only have an elevation of ~8 degrees. With its low elevation, atmospheric dispersion will take its toll and an atmospheric dispersion corrector would greatly help to improve our views of the giant planet and it four Gallilean moons.
- Saturn, will be seen just west of south as darkness falls at the start of the month. Then, its disk is ~16 arc seconds across and its rings - which are still, at 25.2 degrees, nicely tilted from the line of sight - spanning some 39 arc seconds across. During the month its brightness remains +0.6 whilst its angular size falls to 15.4 arc seconds. Sadly, now in Sagittarius and lying on the south-western side of the milky way, it is at the lowest point of the ecliptic and will only reach an elevation of ~13 degrees. As with Jupiter, an atmospheric dispersion corrector will help improve our view.
- Mercury, following its transit of the Sun on the 11th - see Highlight below - Mercury rises rapidly into the pre-dawn sky, increasing in brightness by half a magnitude each day and rising about 7 minutes earlier as the days progress. The rates slow until Mercury reaches greatest western elongation some 20 degrees in angle from the Sun on the 28th. By then, it will have brightened to magnitude -0.5 and will rise one and a quarter hours before the Sun. It will then have an elevation of some 11 degrees before being lost in the Sun's glare.
- Mars, which passed behind the Sun (superior conjunction) on September 2nd, can be seen in the pre-dawn sky at the start of its new apparition. It might just be glimpsed just south of east at the start of the month but will then only have an elevation of ~11 degrees at sunrise. Then, binoculars could well be needed to spot its +1.8th magnitude, 3.7 arc second disk - but please do not use them after the Sun has risen. However, by the end of the month, Mars rises some two and a half hours before the Sun remaining at magnitude -2.8 with disk still less than 4 arc seconds across. It will have risen to ~12 degrees elevation before being lost in the Sun's glare.
- Venus, may just be glimpsed in the west south-west setting an hour after the Sun at the start of the month, but will be difficult to see due to the fact that the ecliptic is at a shallow angle to the horizon and so Venus will have a very low elevation. Bymonth's end the Sun sets just before 4 pm and Venus an hour and a quarter later but it will still be hard to spot with an elevation of just 6 degrees as darkness falls. Its magnitude remains at about -3.8 and its, almost fully illuminated disk, ~11 arc seconds across. Binoculars and a very low horizon will be needed to spot Venus, but please do not use them until after the Sun has set.
- November - still a chance to observe Saturn. Saturn is now low (at an elevation of ~13 degrees) just west of south as darkness falls lying above the 'teapot' of Sagittarius. Held steady, binoculars should enable you to see Saturn's brightest moon, Titan, at magnitude 8.2. A small telescope will show the rings with magnifications of x25 or more and one of 6-8 inches aperture with a magnification of ~x200 coupled with a night of good "seeing" (when the atmosphere is calm) will show Saturn and its beautiful ring system in its full glory.Due to the orientation of Saturn's rotation axis of 27 degrees with respect to the plane of the solar system, the orientation of the rings as seen by us changes as it orbits the Sun and twice each orbit they lie edge on to us and so can hardly be seen. This last happened in 2009 and they are currently at an angle of 25 degrees to the line of sight. The rings will continue to narrow until March 2025 when they will appear edge-on again.
- November, late evening: the Double Cluster and the 'Demon Star', Algol. November is a good time to look high in the Southeast towards the constellations of Cassiopea and Perseus. Perseus contains two interesting objects; the Double Cluster between the two constellations and Algol the 'Demon Star'. Algol in an eclipsing binary system as seen in the diagram below. Normally the pair has a steady magnitude of 2.2 but every 2.86 days this briefly drops to magnitude 3.4.
- November: find Uranus. This month is a good time to find the planet Uranus in the late evening as it reached opposition on October 28th. With a magnitude of 5.7, binoculars will easily spot it and, from a really dark site, it might even be visible to the unaided eye. A medium aperture telescope will reveal Uranus's 3.7 arc second wide disk showing its turquoise colour. It lies in Aries, close to the boarders of Pisces and Cetus as shown on the chart.
- November 1st - after sunset: A crescent Moon between Saturn and Jupiter, after sunset, low in the south-west, Jupiter will be seen down to the lower right of a waxing crescent Moon whilst, up and to its left will be seen Saturn.
- November 9th - before dawn: Mars lies above Spica. Before dawn, low in the southeast, Mars (at magnitide 1.76) will be seen just above Spica (at magnitude 0.95) in Virgo.
- November 11th: A Transit of Mercury. Whereas in 2016 the whole of the transit was visible, this year the Sun will have set (~4:16 pm) well before its end. First contact is at 12:35 when its disk will just impinge onto the Sun's surface with second contact at 12:37. Then, the Sun will have an elevation of ~20 degrees over the south-southwestern horizon. Mercury reaches the midway point of its transit at 3:19 - with the Sun at an elevation of just 7 degrees but will be lost from view long before fourth contact as it leaves the Sun' surface at 6:04. Mercury's disk is just 10 arc seconds across - compared to the Sun's 1938 arc seconds, so a small telescope would be needed to observe the transit should, hopefully, it be clear.As the Sun is at solar minimum, it is unlikely that any sunspots will be visible to be confused with Mercury but, if so, Mercury's disk will appear darker and will, of course, be moving across the Sun's surface.
- November 16th - late evening: the Moon in Gemini. In the late evening, looking southeast, the waning Moon before third quarter will be seen within the constellation Gemini.
- November 22nd - in twilight: Venus lies close to Jupiter. After sunset, looking southwest, Venus will lie just two degrees below Jupiter - with Saturn high and away to the left.
- November 5th and 18th: The Alpine Valley These are two good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb is the Apennine mountain chain that marks the edge of Mare Imbrium. Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image is a thin rill runs along its length which isquite a challenge to observe. The dark crater Plato will also be visible nearby. You may also see the shadow cast by the mountain Mons Piton lying not far away in Mare Imbrium. This is a very interesting region of the Moon!
Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speaks about the Southern Hemisphere night sky during November 2019.
- A bit about November. November is the time when the starcluster known as the Pleiades is visible again in the evening sky. The starcluster is linked to Halloween in the Northern Hemisphere but here, on the other side of the world, we prepare for summer. Here in New Zealand flowers and stars unite at the horizon. Entire hills change colour due to so many wonderful flowers this time of the year and the bulk of stars in the Milky Way surround the horizon like a river. Just after sunset the centre of the galaxy is on the west side of the sky and you can just see the tip of Scorpius and Sagittarius, whereas on the eastern horizon half of Orion, or as people call it here in New Zealand, the pot, emerges from behind it.The Sun rises around 6 AM on the beginning of the month and sets around 8 pm and at the end of the month earlier with about 20 minutes at around 5:40 and 40 minutes respectively later at night setting at about 8:40 .
- Planets, We actually just came back from Rotorua where we enjoyed a bit of stargazing under the beautiful dark sky from there. We spotted the planet Jupiter, still bright, moving now towards Saturn, then of course Saturn and invisible next to it - we did not spot but we knew it was there - Pluto. November is still good to catch up with these two amazing planets if you have not had the chance to look at them yet. At the beginning of the month, Venus and Mercury are very close and joined by Antares and Jupiter make a spectacle in the evening sky. You’ll need a good opening on the horizon to spot them. Keep an eye on Venus all throughout the month. Around ninth of November it will pass close to Antares at about 4 degrees then it will move in closer to Jupiter and Saturn so that on the 24 of November is within one and a quarter degrees to Jupiter. That close enough to fit 2 and a bit full Moons between them, and watch this space around ten of December, when Venus will be within 2 degrees of Saturn. Neptune and Uranus are out there too, Neptune is in Aquarius and Uranus in Aries. .
- Asterisms. November here is called Orongo, which means the time after the great rain. And does it rain in October! November harbours one the most beautiful asterisms I have ever seen, the grand canoe of Tama Rereti, te waka o Tama Rereti. And when I say harbours, it almost really does, the asterism stretches around the horizon as the Milky Way surrounds the horizon.The Milky Way is the canoe, Scorpius is the prow, Southern Cross is the anchor and Orion the stern. The Hyades and Pleiades are the feathers and the wake left behind by the canoe. From the bow, the anchor rope is marked by Alpha Centauri, the third brightest star in the sky, and also Beta Centauri; together these are also known as the Pointers of the Southern Cross. The Southern Cross represents the great stone anchor or Te Punga that keeps the canoe of Tamarereti in its place.
- Southern Cross. This time of the year, the Southern Cross is in its lowest position on the horizon and points down indicating south. If you look up from the Southern Cross, you will come across Achernar, the end of the river Eridanus. On each side of this line are the Large Magellanic Cloud, on the left, and to the right of it, the Small Magellanic Cloud, our beautiful galaxies we admire here in the Southern Hemisphere.
- Magellanic Clouds, - these are a great attraction in November for the simple reason that most of the centre Milky Way now is beyond the horizon or around it so we are looking at them through a layer of atmosphere. By the time Orion has enough height in the sky to observe it properly, it would be December so the Magellanic Clouds are always a good idea for a target to fall onto.Good times for observing would be at the end of the month, we have new moon on the 27 of November and don’t go observing stars on the 13th of November as the Moon is full.
- Transit of Mercury, a spectacular event is going to happen on the morning of the 12th of November (nz time), that is the transit of Mercury. The transit will end as the Sun rises here in Wellington so not the best place to view it but hopefully with a clear eastern horizon we should be able to catch a glimpse.
- Stars and Galaxies, up in the sky, almost at Zenith, is Grus and close to it is Fomalhaut in Piscis Austrinus. As you look up, Fomalhaut, Achernar and another star, Deneb Kaitos of Grus make a triangle. Just below the ecliptic, the great square of Pegasus is riding the Northern horizon. So in November we should be able to see again the brightest stars in the sky in order: Sirius, Canopus and Alpha Centauri and also the most prominent four galaxies The Milky Way, the Magellanic Clouds and very low in the north, the Andromeda Galaxy, easily seen in binoculars in a dark sky and faintly visible to the eye. It appears as a spindle of light.
- From Wellington New Zealand, Haritina Mogosanu and Samuel Leske wish you a fantastic November.
Odds and Ends
A recent Nature paper announced the detection of strontium produced in the merger of two neutron stars. This is significant because it serves as evidence of the so-called r-process by which many heavy elements are thought to be created. It also proves that neutron star mergers provide suitable conditions for these reactions to take place.
Voyager 2 reached interstellar space on November 5th, joining its twin spacecraft Voyager 1, which crossed this boundary in 2012. They are both 42 years into their flights, and still relay data back to earth daily.
Voyager 2 is now at a distance of 120 astronomical units, or 120 times the distance from the earth to the sun. This marks crossing point to interstellar space, which is defined by where the solar wind and the interstellar wind are in balance. This sharp boundary is also known as the heliopause. The crossing was confirmed by onboard instruments, which measured a change in the plasma density between the hot lower density plasma of the solar wind to the cool, higher-density plasma of interstellar space.
Each Voyager spacecraft was launched in a different direction away from the sun, so scientists can now use the data to measure the shape of the heliopause. So far the data confirms that the heliosphere is strikingly symmetric, at least at the two points where the Voyager spacecraft crossed.
Boeing and SpaceX complete crucial tests on their crew capsules.
Boeing’s CST-100 Starliner completed a pad abort test on Monday, this is where they test the systems to get the crew capsule away from the launchpad if things start to go wrong. Apparently it can accelerate away at up to 650 mph in 5 seconds, which sounds a lot but translates to about 6G.The capsule only deployed two of the 3 parachutes, but according to NASA’s testing standards, this is fine and it passed.
SpaceX did slightly better, on Sunday they ran 13 consecutive successful tests of the upgraded parachutes on the Crew Dragon capsule, of which it needed to pass only 10 to pass. Whilst the capsule has 4 parachutes, these tests were to check that the capsule can still land safely if only 3 deploy, so they intentionally disabled the fourth
|Interview:||Connor Smith and Jake Staberg Morgan|
|Night sky:||Ian Morison and Haritina Mogosanu|
|Presenters:||Tiaan Bezuidenhout, Crispin Agar, Roke Cepeda-Arroita|
|Editors:||Joseph Winnicki, Lizzy Lee, Hongming Tang, Tom Scragg|
|Segment Voice:||Tess Jaffe|
|Website:||Michael Wright and Stuart Lowe|
|Cover art:||Image of a galaxy cluster (Abell 370) showing lensing CREDIT: NASA, ESA, the Hubble SM4 ERO Team and ST-ECF|