Download I have heard people call Jupiter a "failed star" that just did not get big

I have heard people call Jupiter a "failed star" that just did not get big
enough to shine. Does that make our sun a kind of double star? And why
didn't Jupiter become a real star?
What indeed is the difference between a big planet and a small star? The recent
discovery of massive planets around other stars has aroused a lot of debate on this very
point. Alan P. Boss of the Carnegie Institution of Washington is one of the theorists
trying to clarify which bodies qualify as planets and which as so-called "brown dwarfs"objects smaller than stars but fundamentally unlike planets. He answers the question
as follows:
"Nearly all scientists who study the formation of planets believe that Jupiter formed in a
very different manner than stars form, so that calling Jupiter a 'failed star' is misleading.
Stars form directly from the collapse of dense clouds of interstellar gas and dust. Because
of rotation, these clouds form flattened disks that surround the central, growing stars.
After the star has nearly reached its final mass, by accreting gas from the disk, the leftover
matter in the disk is free to form planets.
"Jupiter is generally believed to have formed in a two-step process. First, a vast swarm of
ice and rock 'planetesimals' formed. These comet-sized bodies collided and accumulated
into ever-larger planetary embryos. Once an embryo became about as massive as ten
Earths, its self-gravity became strong enough to pull in gas directly from the disk. During
this second step, the proto-Jupiter gained most of its present mass (a total of 318 times the
mass of the Earth). Soon thereafter, the disk gas was removed by the intense early solar
wind, before Saturn could grow to a similar size."
Boss explains further that brown dwarfs may look like planets but they form like stars-that is, they collapse directly from a gas cloud, rather than building up in the disk around a
star. Brown dwarfs lack sufficient mass to shine, so they might more fairly be described as
"failed stars."
Alex Rudolph of the physics department at Harvey Mudd College expands on
this important point:
"Jupiter is called a failed star because it is made of the same elements (hydrogen and
helium) as is the Sun, but it is not massive enough to have the internal pressure and
temperature necessary to cause hydrogen to fuse to helium, the energy source that powers
the sun and most other stars.
"However, Jupiter has only about 0.1 percent the mass of the sun, and as it is definitely not
a star, we can't really call the solar system a double star. It is interesting to note, however,
that more than half of all stars in the sky are part of a binary, triple, or higher multiple star
system (binaries being the most common). So the Sun is unusual in being a loner.
"As for why Jupiter failed to become a star--it probably had to do with the accident of the
sun grabbing most of the mass early in the formation of the solar system, while in other
systems the mass was more equitably distributed; in binary star systems, for example, the
masses of the stars are commonly roughly equal. Stellar formation is a hot topic of current
research, as astronomers are trying to fathom the still-mysterious details of the birth
process.
Analysis of the article:
1. Did the 2 scientists support the idea that Jupiter is a failed star? What evidence do you have for each scientist?
2. When comparing Jupiter and a star, what similarities do they share?
3. What is the critical factor that prevented Jupiter from becoming an actual star?
4. How common are star systems that are composed of more than 1 star? Provide some evidence from the scientists.