2020
August
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Meanwhile, in the outer edges of the Solar System

Gonggong, Quaoar, Orcus, Salacia, Gǃkúnǁ’hòmdímà, Leleākūhonua. You’ve probably never heard of the names of any of these worlds before (except for maybe Quaoar), but they are all very real celestial bodies that likely meet the definition of a dwarf planet and thus would have had the same claim to the title of “planet” as Pluto, right up until the time Pluto was demoted from planet status. The reason you won’t find them on any night-sky charts for amateur astronomers is because their orbits are so far away from the Sun that it was basically a miracle that any of these approximately 600-kilometer-diameter objects were discovered at all.

But why do so many of them travel around the Sun on orbits that are so eccentric and at such an angle relative to the ecliptic that they’ve been named “Detached Objects”? That was the topic of a study from the University of Colorado and published in the Astrophysical Journal. Some researchers, including “Pluto Killer” Mike Brown, believe that a large, previously undetected object, “Planet 9,” is responsible for the orbits of these dwarf planets. And yet, astronomers have been searching for Planet 9 for years without success.

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In the orbit of two giants

Eta Carinae, approximately 7500 light-years from Earth, has everything that an astronomer could want. First, there’s the nebula surrounding Eta Carinae. The so-called Homunculus Nebula is still growing. It has the shape of two opposing cones, whose tips originate in Eta Carinae, and measures more than 0.5 light-years from end to end. From the propagation rate of up to 700 km/s, the existence of the nebula can be traced back to an outburst in the 1840s.

Second, it is not just a single star, but a binary system consisting of two blue giants. The primary star has a mass of 100 solar masses and is thus one of the most massive stars in the Milky Way. But even the secondary star is not a lightweight. It is 30 times heavier than our home star.

Both stars also orbit each other once every 5.5 years at a very close distance. Sometimes they come as close as the Sun and Mars, then move as far apart as the Sun and Uranus. At a cosmic scale, however, that is still just a stone’s throw away, and thus they inevitably each hurl large portions of their mass at each other in the form of dense, supersonic stellar winds made from charged particles. In this way, in only about 5000 years, the primary star loses as much mass as our Sun has in total. The secondary star propels a stellar wind moving at about eleven million kilometer per hour (corresponds to at least one percent of the speed of light).

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How does a star simply vanish?

PHL 293B, also known as HL 293B, the Kinman dwarf galaxy, A2228-00, or SDSS J223036.79-000636.9, is a small, not especially bright galaxy 75 million light-years from the Sun. It belongs to a class of so-called “blue compact dwarf galaxies.” These normally consist of several large, young star clusters containing hot, massive stars. The brightest of these are blue – thus the designation of the galaxies and their color.

PHL 293B is no different. Between 2001 and 2011, astronomers observed that the dwarf galaxy was dominated by a blue giant, a “luminous blue variable” (LBV), which shines approximately 2.5 million times brighter than the Sun. Such stars, as you might suspect from their name, are unstable and dramatic changes in their spectrum and brightness are the rule, not the exception. These variations leave behind specific traces that can be identified by scientists.

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When you gotta go, you gotta go, even on the Moon…

Space is harsh and uncomfortable. That’s true for all human bodily functions. But maybe you’ve spent some time thinking about this problem and you have an idea for the perfect space toilet? It could win you $20,000 if it meets the following specifications:

General requirements

  • Easy to use
  • Odor control
  • Usable for at least 14 days
  • Usable for urine, feces, vomit, diarrhea, menses
  • Usable by female and male users between 58 to 77 inches tall and 107 to 290 lbs
  • Also usable by sick crew members, e.g., able to capture vomit without requiring the crew member to put his/her head in the toilet

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Moving blocks of ice around on Triton – the reality

May 24, 2082, Neptune’s moon Triton: The hero of one of my novels, Nick, tries to move a block of ice weighing 80 kg (176 lbs). But it’s damn hard, even with Triton’s low force of gravity. “On Earth, the ice would slide because its bottom would melt due to the pressure, like under the blade of a skate, but it’s too cold for that here,” Nick thinks.

A mistake, a Swedish reader just wrote to me. The idea that ice skating works because ice melts under pressure and then forms a lubricating layer is old. Ice does in fact heat up under pressure, but not nearly enough or fast enough to melt and create a lubricating layer. My mistake: I read the idea somewhere and didn’t review it again for accuracy while I was writing.

There’s a lot more to it than just a lubricating layer. Ice skating is one of the rare everyday phenomena that have not been definitively explained yet by science. You already know, of course, that it works, and best results are given at a temperature of -7 °C, which is why the ice in sports arenas is kept at that temperature. But it also works at temperatures below -20 °C, where water no longer melts due to pressure.

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How a steam-powered robot could explore Enceladus

The thing designated SPARROW that engineers from NASA’s Jet Propulsion Laboratory want to send to the icy moons of Enceladus and Europa has nothing at all in common with its namesake bird. Americans and scientists love acronyms, and the designation SPARROW came from the name “Steam Propelled Autonomous Retrieval Robot for Ocean Worlds.” The project is part of the “NASA Innovative Advanced Concepts” program (NIAC), whose current candidates were announced by NASA earlier in Spring 2020.

SPARROW stands out because it uses a very old propulsion solution from the start of the Industrial Age. But instead of coal for steam locomotives, it uses steam for a rocket propellant. To do this, SPARROW heats and melts the abundantly plentiful ice. With short bursts of steam, the approximately soccer ball-sized robot can then make large hops in the low gravity of the icy moons. The concept involves a lander base unit releasing and coordinating several SPARROWs.

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Too heavy to be a neutron star, too light to be a black hole

Sometimes (always?), new research instruments like the Ligo-Virgo gravitational wave detector collaboration not only provide long expected answers to old questions, but also create completely new questions too. Take, for example, GW190412, which is the designation given to the latest conundrum, for which physicists can thank Ligo-Virgo. It refers to a gravitational wave burst that reached Earth on 14 August 2019. From the measured data, the researchers determined that a relatively lightweight object and a significantly more massive object must have merged together to form a black hole with a mass of now 25 solar masses.

There’s no question about the nature of the heavier object, which was determined to have a mass of 23 solar masses and thus had to be a black hole. But the smaller object, at 2.6 solar masses, was too heavy to be a neutron star, but also too light to be a black hole. The fate of a star is determined by its original mass. When it dies and explodes, all that remains is either a neutron star with a mass of maximum 2.5 solar masses (called the Tolman-Oppenheimer-Volkoff limit) or a black hole that is significantly more massive. The previously lightest known stellar black hole had a mass of 5 solar masses. It had seemed that there could be no objects within this rather large gap.

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How many civilizations are there in the Milky Way?

Are there other thinking creatures in the universe? Researchers recently determined that life should be at least relatively common. In terms of intelligence, however, the results, which were based on an analysis of its development on Earth, were less clear.

A new article published in the Astrophysical Journal has come to somewhat more encouraging results. Astrophysicist Tom Westby, one of the authors, explains his group’s approach: “The classic method for estimating the number of intelligent civilizations relies on making guesses of values relating to life. Opinions about such matters, however, vary quite substantially. Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our galaxy.”

The value that the researchers came up with was 42. Okay, not really, that was just a little joke. Westby continues:

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