WEBVTT FILE

1
00:00:00.001 --> 00:00:13.535
Our galaxy contains at least 200 billion stars.
Yet the details of how they formed remain mysterious.

2
00:00:13.535 --> 00:00:22.508
Scientists know that stars form from
the collapse of huge hydrogen clouds...

3
00:00:22.508 --> 00:00:31.481
...that are squeezed under gravity
until nuclear fusion ignites.

4
00:00:31.511 --> 00:00:40.632
But only about 30 percent of the cloud’s gas
ends up in the newborn star.

5
00:00:40.646 --> 00:00:49.544
So, where does the rest of the hydrogen go?

6
00:00:49.544 --> 00:01:05.452
Astronomers had assumed that a forming star
blows off gas through stellar winds and jets.

7
00:01:05.452 --> 00:01:13.980
These winds and jets should stop further growth of the star.

8
00:01:13.980 --> 00:01:31.557
They should also create cavities in the surrounding
gas that widen until the cloud dissipates.

9
00:01:31.558 --> 00:01:41.421
But a new study shows something different.

10
00:01:41.460 --> 00:01:56.293
Using observations from NASA’s
Hubble and Spitzer space telescopes
and ESA’s Herschel Space Observatory...

11
00:01:56.293 --> 00:02:10.000
...researchers studied 304 developing stars
in a region called the Orion Complex.

12
00:02:10.000 --> 00:02:22.756
They found that the cavities around the stars
did not grow over time, as expected.

13
00:02:22.756 --> 00:02:34.621
In fact, the cavities don’t seem to expand
until the stars push out all of the gas in the cloud.

14
00:02:34.621 --> 00:02:48.193
If stars don't end up isolated in cavities,
why doesn't the gas find its way into the star?

15
00:02:48.193 --> 00:02:57.685
For now, the answer remains a mystery.

16
00:02:57.685 --> 00:03:02.015
[ SILENCE ]