Sky & Telescope - March 2019 - 43

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Binocular Highlight by Mathew Wedel

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CANCER

Fly By Night

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WHEN TO
USE THE MAP

Late Jan
Early Feb
Late Feb
Early Mar
Late Mar

Midnight
11 p.m.
10 p.m.
9 p.m.
9 p.m.*

*Daylight-saving time

ere's something I stumbled upon last spring:
a winged asterism at the western end of Leo
Minor. The anchor star is 10 Leonis Minoris, which
forms an isosceles triangle with Alpha (α) and 38
Lyncis about 3° farther west. I initially sketched the
asterism as a seagull, but on subsequent visits 9
Leonis Minoris and 10 LMi struck me as the yellow eyes of a bat. Whatever you call it, this night
flyer is above the horizon before midnight between
November and July, but it only flies right-side up
when the bright stars Pollux and Procyon are crossing the meridian (see chart at left). Hang on to Pollux
and Procyon, we'll have need of them in a minute.
The "eyes," 9 and 10 Leonis Minoris, are both
giant stars, larger, cooler, and more yellow-orange
than the Sun. The stars that form the wings are
mostly yellow-white main-sequence stars, with a few
orange giants thrown in. A couple of them make for
interesting comparisons. The star nearest the bird's
body in the eastern "wing," 11 Leonis Minoris, is a
G-type main-sequence star very similar to our own
Sun. It gives us a pretty good idea of what the Sun
would look like from 37 light-years away. Pollux, 25°
southwest in Gemini, the Twins, is about the same
distance from Earth, 34 light-years, but as a K-type
orange giant it's much brighter.
Now have a look at HD 81440, the middle star
in the western "wing." It's an F-type yellow-white
main-sequence star. In terms of size and spectral
class it's a close match with Procyon, which lies 40°
away in Canis Minor, the Little Dog. The difference in
apparent brightness is down to distance: HD 81440
lies 350 light-years away, versus a mere 11 lightyears for Procyon.
¢ MATT WEDEL is gazing into the starry abyss and
having fun cataloging whatever gazes back.
sk yandtele scope.com * M A RCH 2 019

43
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Sky & Telescope - March 2019

Table of Contents for the Digital Edition of Sky & Telescope - March 2019
