Astronomy

48 ASTRONOMY • SEPTEMBER 2017

“Astrometry, it turns out, is
just tough to do from the
ground because we’re looking
through Earth’s atmosphere
and the stars are twinkling,”
Fischer says.
One of the f law’s discoverers
was the new Sproul Observatory
head, Wulff-Dieter Heintz.
Another observatory employee,
John L. Hershey, published a
paper in The Astronomical
Journal in June 1973. Hershey
had studied the tiny M-dwarf
star Gliese 793, and as he pored
through photographic plates,
he noticed something: It had
the exact same data discontinu-
ity as Barnard’s Star.
But the United States Naval
Observatory and Allegheny
Observatory at the University
of Pittsburgh found no shift in
the motion of Barnard’s Star.
“When his work was
checked over by other observa-
tories using the more powerful
plate constant method, his
unseen planetary companions

to Barnard’s Star vanished,”

DeVorkin says.

That didn’t deter van de

Kamp, but it did damage his

friendships with Heintz and

George Gatewood, the astrono-

mer at Allegheny who con-

firmed the lack of perturbations

in the motion of Barnard’s Star.

As late as the 160th Meeting of

the American Astronomical

Society, held in Troy, New York,

in 1982, van de Kamp was still

pushing for his planets.

“Current analysis for one

orbit clearly yields a perturba-

tion with a period of 12 years,”

his abstract read. “As before, a

desirable improvement is made

by an additional perturbation

with a period of 20 years.”

Incidentally, at this same

conference, van de Kamp’s pro-

tégé Lippincott presented the

possibility of planetary-mass

companions around three other

stars. One of those stars,

Luyten’s Star, has been recently

confirmed to host planets.

However, Lippincott suggested

two long-period gas giants,

whereas the planetary compan-

ions found in March 2017 were

a super-Earth and an Earth-

mass planet. These planets

don’t account for the magni-

tude of Lippincott’s possible

detection. Another 1982 paper

by Lippincott suggested — but

far from asserted — that a

planet could cause f lare activity

on EV Lacertae.

“In general, people have

been skeptical about planetary

discoveries, often for good rea-

son — [van de Kamp’s] is far

from the only claim of a plan-

etary discovery that turned out

to be incorrect,” Jensen says.

“And even the initial discover-

ies of exoplanets in the mid-

1990s were met with some

skepticism initially, though of

course now we have over-

whelming evidence of the rich

diversity of planets around

other stars.”

Luyten’s Star is the only star

in van de Kamp’s cadre with a

confirmed planetary system. To

date, no planets have been

found around Barnard’s Star,

Lalande 21185, or 61 Cygni.

Gatewood did present a

paper in 1996 claiming that he

had found several planetary-

mass companions around

Lalande 21185. This result, too,

was based on astrometry.

Gatewood’s planets also were

cast in doubt and remain

unconfirmed. A February 2017

paper suggested evidence of a

3.8-Earth-mass planet, though

it also remains ambiguous.

Lalande 21185 just can’t

catch a break.

Still, van de Kamp’s work

left him “highly respected” at

the end of his career, according

to DeVorkin. And Sproul

Observatory has since been

replaced at Swarthmore with a

new one: Peter van de Kamp

Observatory. As part of the

Kilodegree Extremely Little

Telescope program, the obser-

vatory has turned up planets

— this time, real ones.

“Our collaboration has

published discoveries of about

15 exoplanets so far, and many

of the discovery papers include

data from our telescope here,”

Jensen says. “Although van de

Kamp was wrong about Barnard’s

Star, he made important contri-

butions to astronomy, and I’m

pleased that we can honor and

remember his work by having

his name on our observatory.”

Van Biesbroeck 8B

When astronomers discov-

ered an object around van

Biesbroeck 8 (vB8) in 1984,

they weren’t quite sure what

they were seeing. The New

Yo rk Ti m e s ran the headline

“Possible Planet Found Outside

the Solar System,” with author

John Noble Wilford stating, “If

this is indeed a planet, the dis-

covery would be a clear break-

through in the long search for

extrasolar planetary systems

and the first direct evidence to

support a premise underlying

theories of possible extrater-

restrial life, which is that plan-

etary systems are not unique to

the Sun and may even be com-

mon in the universe.”

But there was a problem

with the puff of gas that had

been spotted in the infrared:

Although it was the size of

Jupiter, further studies showed

an outsized inf luence on its

parent star. In fact, this is a

common problem in the hunt

for planets. There are objects

that are neither stars nor plan-

ets, called brown dwarfs, which

can be easily mistaken for plan-

etary companions. Mass esti-

mates on vB8’s companion were

hard to nail down — some-

where between 30 and 80

Jupiter masses. To several

astronomers, this indicated a

brown dwarf.

Jill Tarter of the SETI

Institute first gave brown

dwarfs their name. Brown

dwarfs accumulate matter in

the same way as stars, but fail

to attain enough mass to ignite

hydrogen fusion. Stars fuse

hydrogen into helium, which

can only occur above a certain

The early years of planetary detection sparked debate as discoveries

accumulated. Of the first 19 planets discovered, half were actually

brown dwarfs. The problem persists today, as more accurate mass

measurements of hefty planets reveal instead brown dwarfs.

In 2009, the Kepler telescope inundated astronomers with new

data. Previous false detections were relabeled candidates, while some

candidates became false detections. But only one confirmed Kepler

planet has ever been retracted: Kepler-32e, the result of a clerical error.

The Gliese 581 system has seen quite the volley back and forth. In

2010, astronomers found two or three potentially habitable planets:

Gliese 581b, c, and e. But the proposed Gliese 581f was soon ruled out,

while the status of Gliese 581g, the most potentially habitable planet,

has long been cast in doubt.

Alpha Centauri Bb, discovered in 2012, was such a weak detection

that it became a high-profile retraction. Many of the planet’s discover-

ers joined the Pale Red Dot team, which successfully found the Earth-

mass planet Proxima Centauri b in the same system in 2016. — J. W.

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