How to find newborn planets without seeing them

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Astronomers Use The Doppler Effect To Find Three Newborn Planets

For Forbes:

We can’t witness the birth of our own Solar System, but the Atacama Large Millimeter/submillimeter Array (ALMA) is providing a picture of how it may have happened. ALMA spotted signs of three giant planets forming around a young star in our cosmic neighborhood. The technique astronomers used to study these planets is one that can be used to find other newborn worlds, and see exactly how clouds of gas and dust turn into something like the Solar System.

The star, which astronomers gave the memorable name HD 163296, is only about 4 million years old, which in cosmic terms makes it a baby. Researchers used ALMA to take detailed images of the disk of dust and gas surrounding the star, which showed three gaps. By studying the motion of carbon monoxide gas within the disk, the astronomers showed it was being moved by massive objects living in those gaps — a telltale sign of newborn planets. These findings were published in a pair of articles in Astrophysical Journal Letters.

[Read the rest at Forbes…]

Strange asteroid may have been born in another star system

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Strange Asteroid May Be A Permanent Alien Guest

strange asteroid 2015 BZ509

The strange asteroid 2015 BZ509 (circled), which may have been born orbiting another star before getting kicked out and joining our Solar System. [Credit: C. Veillet/LBTO]

For Forbes:

Last fall, an asteroid we named ʻOumuamua passed through the Solar System. Its visit marked the first time we’ve identified an object inside the Solar System that definitely came from outside. However, a new study argues that we might have a more permanent interstellar guest: a weird asteroid called 2015 BZ509.

Thousands of asteroids swarm around Jupiter’s orbit, but they all orbit the same direction as the giant planet except 2015 BZ509. This weirdo orbits the opposite direction — “retrograde” in technical terms — at a highly tilted angle. Fathi Namouni and Helena Morais performed a computer simulation which demonstrates that 2015 BZ509 could stay in its orbit for billions of years, but it’s unlikely it formed there when the rest of the Solar System was born. Instead, the authors argue, it probably originated outside the Solar System and drifted in, where it was captured by gravity.

[Read the rest at Forbes]

Artist’s conception of the Kuiper belt. [Credit: Don Dixon]

When we talk about big advances in planetary science, we often are thinking about Mars rovers or the discovery of exoplanets. However, one area where we’ve learned a lot over the last few decades is the Kuiper belt: a region beyond the orbit of Neptune inhabited by small bodies of ice and rock. Before 1992, Pluto was the most distant known Solar System object, but between then and now, astronomers have discovered a wealth of Kuiper belt objects (KBOs).

A new paper (coauthored by Mike Brown of Pluto-killing infamy) describes a puzzle arising from a survey of many KBOs: some of them don’t fit in with the standard model of planet formation:

A new study of large scale surveys of KBOs revealed that those with nearly circular orbits lying roughly in the same plane as the orbits of the major planets don’t fit the Nice model, while those with irregular orbits do. It’s a puzzling anomaly, one with no immediate resolution, but it hints that we need to refine our Solar System formation models. [Read more…]

Some planet-like Kuiper belt objects don’t play “Nice”

Imagine a planet 7 times the mass of Jupiter, hot enough to glow slightly, and containing dusty clouds of carbon monoxide and water. That planet is HR 8799c, one of the few worlds outside our Solar System which astronomers have been able to image directly. Part of the reason for its weirdness is its youth: the planet is only about 30 million years old, compared to the Solar System’s 4.5 billion-year age. In fact, up until an observation published this week, astronomers couldn’t be sure HR 8799c was even a planet: many of its properties make it look more like a brown dwarf, the star-like objects not quite massive enough to shine via nuclear fusion. Despite its strange aspects, the planet could help astronomers understand how the HR 8799 system formed—and reveal information about the origins of our own Solar System.

Quinn Konopacky, Travis Barman, Bruce Macintosh, and Christian Marois performed a detailed spectral analysis of the atmosphere of the possible exoplanet. They compared their findings to the known properties of a brown dwarf and concluded that they don’t match—it is indeed a young planet. Chemical differences between HR 8799c and its host star led the researchers to conclude the system likely formed in the same way the Solar System did. [Read more…]

Analysis of atmosphere reveals: weird exoplanet is weird

Vesta is the second-largest asteroid in the Solar System, and recent measurements by the Dawn mission showed that it’s actually a protoplanet: a piece of planet-like material left over from the early days of our Solar System. However, Dawn is significantly non-spherical and very battered. Most notably, it has two huge overlapping craters near its south pole, marking impacts that nearly shattered the asteroid, and which raised a mountain higher than any other in the Solar System. Now, a computer simulation may have showed how Vesta came to be the fascinating, scarred, wonderful object we see today.

As with other Solar System bodies, Vesta bears the scars of its history. The most substantial of these scars are the two large impact basins, Veneneia and Rheasilvia. (Both craters were named for virgins who served the goddess Vesta in Roman mythology—the vestals.) Rheasilvia formed about 1 billion years ago and is larger. Veneneia is smaller and formed at least 2 billion years ago; its presence was partly obscured by the later impact. Meteorites from Vesta, possibly ejected by the impacts forming Rheasilvia and Veneneia, have been found on Earth. [Read more….]

Kaboom! A simulation shows how impacts shaped and nearly destroyed Vesta