This episode's object is the star system HD 69830 in the constellation Puppis. For reference, Puppis is one of the three modern day constellations that used to constitute the much larger constellation Argo Navis, which depcited the mythological ship used by the Argonauts, but people started treating Puppis as its own constellation after French astronomer and general weirdo Nicolas Louis de Lacaille split up the larger Argo Navis in 1756 [1].
Anyway, HD 69830 is a yellowish star about 0.86 times the mass the Sun located at a distance of 41 light years (12.6 pc) from Earth [2, 3], which places it just out of range of my Star Wars sound effects. It's apparent magnitude is about 6 [2, 3], so it's just at the threshold of what people can see without a telescope, although people need really good eyesight to see it, and they need to be someplace without any lights from buildings or other manmade objects, and the Moon can't be shining. Even so, it's really hard to tell the difference between this star and all of the other stars in the area.
Anyway, as a relatively nearby star that is very similar to the Sun, astronomers have spent a lot of time looking at HD 69830 to try to find interesting things in the star system, like exoplanets and such.
The first hint that the HD 69830 system contained something interesting was when observations with the Spitzer Space Telescope published in 2005 detected extra amounts of infrared light from the star system [4]. The most common source of infrared light in space is dust, so people concluded that HD 69830 was surrounded by a disk of dust. Additional observational analyses have shown that the dust disk lies within a region that is less than 1 Astronomical Unit (AU) from the star [5], which means that the dust disk would fit within the radius of the Earth's orbit. Since HD 69830 seems to be billions of years old, this dust disk would not be leftover material from the nebula that the star formed out of but instead would be something that was created by the collision of asteroids or comets or other planetary objects in the system. However, this would mean that asteroids and comets are actively colliding with each other, which would be quite surprising for a star system that is billions of years old, and people are still trying to figure out exactly how the dust disk got there.
To add to the excitement, in 2006, another paper was published announcing that people had found the presence of three exoplanets orbiting the star [6]. These exoplanets were all found by observations of the slight Doppler shifting of light from the star caused by the gravitational pull of the exoplanets as they orbited the star. All three of these exoplanets have been described as hot Neptunes, which means that they are all the size of Neptune, but because they are all close to their host star, they are all much hotter than Neptune [6].
The exoplanets have the designations HD 69830b, c, and d, with b being the innermost planet and d being the outermost. The radii of the orbits of the three exoplanets range from 0.0785 to 0.630 AU, which means that the two inner exoplanets are closer to their host star than Mercury is to the Sun, but the outermost exoplanet orbits its host star at a distance almost equivalent to the distance between the Sun and Venus [6]. The orbital periods of the three exoplanets range from slightly less than 9 days, which is really fast, to a more mellow 197 days, which is also close to Venus's orbital period.
The discovery of these three exoplanets was really exciting in 2006, mainly because finding star systems with multiple exoplanets was much harder back then. Also, in terms of searching for life in other star systems, the inner two exoplanets are too close to the star for any moons orbiting those planets to harbor life similar to what we find on Earth (and the exoplanets themselves are gas giants which would add extra difficulties to the formation of life), but the third is just at the inner edge of the star system's habitable zone, meaning that moons orbiting the planet could pontentially host life [7]. However, since the exoplanets were discovered, people actually seem to have taken slightly more interest in the dust disk. Finding a star system with multiple exoplanets seems more commonplace these days, and in fact, people have found such systems that contain multiple planets that are closer to the Earth's size, making them more interesting than the hot Neptunes orbiting HD 69830. In contrast, the dust disk still seems to be quite unusual and difficult to explain even 20 years after its discovery was published, and it seems like it would take a lot of asteroid collisions to make the disk. Expect more research into the dust disk specifically to come out in the future.