Sky and Telescope - August 2017 - 40

Vera Rubin: Her Life & Work

With the help of Ford and many Carnegie postdocs, Rubin
studied all kinds of galaxies, including the more irregular
ones. They were each special in their own way, but they all
shared at least one common characteristic: a ﬂat rotation
curve. The ﬂatness of the curves was just so easy to see, Rubin
said. "You could show someone a couple of spectra," which
revealed the stars' velocities around the galaxies, and "they
knew the whole story."
"Vera was motivated by the science. She had no patience
for astro-politics," Hunter says. "She was very careful about
reducing and analyzing the data and listening to what the
data were telling her, rather than what she expected the data
to tell her."
Because Rubin was so data driven, Hunter says, she was
conﬁdent in her results and fearless in standing up for them
when others expected different answers.
"So much of Vera's success came from who she was on
the inside," says Sara Seager, an astrophysicist and planetary
scientist at MIT: Rubin was always positive, encouraging,
and tenacious.
Faced with the ﬂat rotation curves, astronomers had to
concede that their conception of the cosmos was missing
something signiﬁcant. Some sort of invisible matter had to
be ﬁlling galaxies and cocooning them in far-reaching halos,
keeping the gravitational force on seemingly "outskirt" stars
strong and enabling their high velocities. Dark matter, as
Zwicky had suggested, had to exist.

A Continued Quest
Dark matter, even decades later, still remains a mystery (see
page 28) - but one that never really bothered Rubin, says
40

A U G U S T 2 0 1 7 * SK Y & TELESCOPE

¢ ASHLEY YEAGER is a freelance science writer and editor,
with a keen interest in astronomy and physics. This article is
adapted from her 2008 MIT master's thesis.

p STARSTRUCK Rubin paired a profound passion for astronomy with
a delightful personality. She passed away on December 25, 2016, at the
age of 88, survived by three of her four children. She appears here in a
photo from 2010.

DINNER: AIP EMILIO SEG RÈ VISUA L A RCHIV ES, RUBIN COLLECTION;
BOT TOM: THE WASHINGTON POST / LINDA DAVIDSON / G E T T Y IM AG ES

p PART OF THE CLUB The influential astronomer Allan Sandage (left),
known for his work on galaxy formation and other topics, encouraged
Rubin in her work - even breaking Palomar regulations by inviting her to
observe there. Sandage and Rubin appear here with Vatican Observatory
astronomer Martin McCarthy at a dinner party.

Princeton astrophysicist Neta Bahcall. Rubin took the mystery as encouragement and a reminder to be humble, sometimes wondering aloud that, if we can't ﬁgure out what dark
matter is, what else is out there that we don't understand?
It was that curiosity that had Rubin returning to the
telescope again and again, even in her late 70s. "I will always
cherish the pure joy Vera derived from science," Hunter says.
"She would get very excited about telescope proposals, being
assigned telescope time, and analyzing data."
The last time Hunter and Rubin were at Kitt Peak - perhaps the last observing run Rubin ever did before her death
on Christmas Day, 2016 - they were looking at a galaxy
called UGC 2885, which is located 270 million light-years
from Earth in the direction of the constellation Perseus. The
galaxy is gigantic: It's 10 times larger than the Milky Way
(depending on whom you ask) and rotates slowly, once every
two billion years. Our galaxy, by contrast, spins around once
every 230 million years or so. Rubin began observing this
galaxy in the 1970s, and now she wanted to use the newest technology available to see if she could push her rotation
curves even farther, measuring the velocities of material far,
far beyond the galaxy's center.
Thus even in her ﬁnal years, Rubin was aiding in astronomers' quest to uncover the boundary where a galaxy's dark
matter halo drops off - or, whether the halo touches its
nearest neighbors. Answering this question will offer clues
to where dark matter is in the cosmos and how it's spread
throughout space, something we might not ever have come to
consider had Rubin not fallen in love with the stars.

Sky and Telescope - August 2017

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