1,000-light-year wide bubble surrounding Earth is source of all nearby,
young stars

Date:
January 12, 2022
Source:
Harvard-Smithsonian Center for Astrophysics
Summary:
The Earth sits in a 1,000-light-year-wide void surrounded by
thousands of young stars -- but how did those stars form? For the
first time, astronomers have retraced the history of our galactic
neighborhood, showing exactly how the young stars nearest to our
solar system formed.



FULL STORY ==========================================================================
The Earth sits in a 1,000-light-year-wide void surrounded by thousands
of young stars -- but how did those stars form?

==========================================================================
In a paper appearing Wednesday in Nature, astronomers at the Center
for Astrophysics | Harvard & Smithsonian (CfA) and the Space Telescope
Science Institute (STScI) reconstruct the evolutionary history of our
galactic neighborhood, showing how a chain of events beginning 14 million
years ago led to the creation of a vast bubble that's responsible for
the formation of all nearby, young stars.

"This is really an origin story; for the first time we can explain how
all nearby star formation began," says astronomer and data visualization
expert Catherine Zucker who completed the work during a fellowship at
the CfA.

The paper's central figure, a 3D spacetime animation, reveals that all
young stars and star-forming regions -- within 500 light years of Earth
-- sit on the surface of a giant bubble known as the Local Bubble. While astronomers have known of its existence for decades, scientists can now
see and understand the Local Bubble's beginnings and its impact on the
gas around it.

The Source of Our Stars: The Local Bubble Using a trove of new data and
data science techniques, the spacetime animation shows how a series of supernovae that first went off 14 million years ago, pushed interstellar
gas outwards, creating a bubble-like structure with a surface that's
ripe for star formation.



========================================================================== Today, seven well-known star-forming regions or molecular clouds -- dense regions in space where stars can form -- sit on the surface of the bubble.

"We've calculated that about 15 supernovae have gone off over millions
of years to form the Local Bubble that we see today," says Zucker who
is now a NASA Hubble Fellow at STScI.

The oddly-shaped bubble is not dormant and continues to slowly grow,
the astronomers note.

"It's coasting along at about 4 miles per second," Zucker says. "It has
lost most of its oomph though and has pretty much plateaued in terms
of speed." The expansion speed of the bubble, as well as the past and
present trajectories of the young stars forming on its surface, were
derived using data obtained by Gaia, a space-based observatory launched
by the European Space Agency.



========================================================================== "This is an incredible detective story, driven by both data and theory,"
says Harvard professor and Center for Astrophysics astronomer Alyssa
Goodman, a study co-author and founder of glue, data visualization
software that enabled the discovery. "We can piece together the history
of star formation around us using a wide variety of independent clues: supernova models, stellar motions and exquisite new 3D maps of the
material surrounding the Local Bubble." Bubbles Everywhere? "When the
first supernovae that created the Local Bubble went off, our Sun was
far away from the action" says co-author Joa~o Alves, a professor at the University of Vienna. "But about five million years ago, the Sun's path
through the galaxy took it right into the bubble, and now the Sun sits --
just by luck -- almost right in the bubble's center." Today, as humans
peer out into space from near the Sun, they have a front row seat to the process of star formation occurring all around on the bubble's surface.

Astronomers first theorized that superbubbles were pervasive in the
Milky Way nearly 50 years ago. "Now, we have proof -- and what are
the chances that we are right smack in the middle of one of these
things?" asks Goodman.

Statistically, it is very unlikely that the Sun would be centered
in a giant bubble if such bubbles were rare in our Milky Way Galaxy,
she explains.

Goodman likens the discovery to a Milky Way that resembles very hole-y
swiss cheese, where holes in the cheese are blasted out by supernovae, and
new stars can form in the cheese around the holes created by dying stars.

Next, the team, including co-author and Harvard doctoral student Michael
Foley, plans to map out more interstellar bubbles to get a full 3D
view of their locations, shapes and sizes. Charting out bubbles, and
their relationship to each other, will ultimately allow astronomers to understand the role played by dying stars in giving birth to new ones,
and in the structure and evolution of galaxies like the Milky Way.

Zucker wonders, "Where do these bubbles touch? How do they interact
with each other? How do superbubbles drive the birth of stars like our
Sun in the Milky Way?" Additional co-authors on the paper are Douglas Finkbeiner and Diana Khimey of the CfA; Josefa Gro?schedland Cameren
Swiggum of the University of Vienna; Shmuel Bialy of the University
of Maryland; Joshua Speagle of the University of Toronto; and Andreas
Burkert of the University Observatory Munich.

========================================================================== Story Source: Materials provided by Harvard-Smithsonian_Center_for_Astrophysics. Note: Content may be edited
for style and length.


========================================================================== Related Multimedia:
* YouTube_video:_A_Bubbly_Origin_for_Stars_Around_the_Sun ========================================================================== Journal Reference:
1. Zucker, C., Goodman, A.A., Alves, J. et al. Star formation near
the Sun
is driven by expansion of the Local Bubble. Nature, 2022 DOI:
10.1038/ s41586-021-04286-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220112121510.htm
--- up 5 weeks, 4 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)