Sky & Telescope - February 2024 - 49

BOB KING
to pin down a solitary point of light.
But I eventually got the hang of it.
Leslie Peltier, who wrote the beloved
Starlight Nights about his experiences
as a variable-star observer and comet
hunter, recounted the same frustration
when hunting for R Leonis, his very
first variable.
Peltier was 18 years old when he
encountered the star with his 2-inch
brass refractor purchased with the
money he made picking strawberries.
He finally spotted R Leonis on March
1, 1918, after many unsuccessful
attempts. It became a favorite. Peltier
made certain to observe the star and
estimate its magnitude each March to
commemorate the night they first met.
If you decide to take the R Leo challenge
this month, heed Peltier's words:
" . . . I feel it is my duty to warn any
others who show signs of star susceptibility
that they approach the observing
of variable stars with the utmost caution.
It is easy to become an addict, and
as usual, the longer the indulgence is
continued the more difficult it becomes
to make a clean break and go back to a
normal life. "
To entice you further down the
variable-star rabbit-hole, take a look at
X Leonis, located just 1° northeast of R.
Although both fit into the same lowpower
field of view, the causes of their
variability couldn't be more different. X
Leonis is actually a binary star where an
Earth-size white dwarf is paired in a tight
orbit with a red dwarf. The white dwarf's
powerful gravity strips gas from its
companion and funnels it into a swirling
accretion disk. Changes in the amount
and rate of material flowing through the
spinning disk causes the disk to heat up,
triggering a sudden brightness spike.
In its quiescent state, X Leonis hovers
around magnitude 16, but during a flare
it can vault four or more magnitudes
overnight to 12 - within reach of a
6-inch telescope under a dark sky. Use
the AAVSO chart utility to make a closeup
map showing comparison stars.
If you like surprises, dwarf novae
like X Leonis are must-see astronomical
targets. Let neighboring R Leonis
take you there.
Young Moon
Season Begins
LATE WINTER AND early spring are the
best times of year to hunt for the young
Moon at dusk. That's when the angle the
ecliptic makes to the horizon from midnorthern
latitudes pitches up so steeply
that the waxing lunar crescent hovers
almost directly above the setting Sun.
February's thin, sickle-like Moon
will serve as a warm-up for its more
challenging appearance in March. The
February new Moon occurs at 5:59
p.m. EST on the 9th, making the fresh
crescent at sunset on the 10th approximately
23.5 hours old as seen from the
East Coast and 26.5 hours old from the
West. A day-old lunar sliver is a great
catch and gorgeous sight.
Bring binoculars and look low in the
western sky starting about 20 minutes
after sunset on February 10th, when
the Moon hovers roughly 6° high from
the East Coast and 8° from the West
Coast. At that time, it stands about
14° from the Sun with an illuminated
extent of 1.6%.
Things tighten up even more in
March. New Moon is on the 10th at
5:00 a.m. EDT. By the time the Sun sets
Minima of Algol
Jan.
UT
1
4
7
9
12
15
18
21
24
27
29
7:23
4:12
1:01
21:50
18:40
15:29
12:18
9:08
5:57
2:46
23:36
These geocentric predictions are from the recent
heliocentric elements Min. = JD 2457360.307 +
2.867351E, where E is any integer. They were
derived by Roger W. Sinnott from 15 photoelectric
series in the AAVSO database acquired during
2015-2020 by Wolfgang Vollmann, Gerard Samolyk,
and Ivan Sergey. For a comparison-star chart
and more info, see skyandtelescope.org/algol.
pPerseus is conveniently positioned near
the zenith during evening hours in February.
Every 2.87 days, Algol (Beta Persei) dips from
its usual magnitude 2.1 to 3.4 and back. Use
this chart to estimate its brightness in respect
to comparison stars of magnitude 2.1 (Gamma
Andromedae) and 3.4 (Alpha Trianguli).
sk yand tele scope .o r g * FEBRUARY 2024 49
Feb.
1
4
7
pA 1.3-day-old evening crescent Moon cuts a
sharp figure low in the western sky on March 7,
2019. Observers will have several opportunities
to spot successive young Moons at dusk this
February and March. Binoculars are an aid in
finding the lunar sliver in bright twilight.
on that date around 7:00 p.m. local
time, the waxing Moon will have aged
just 14 hours as seen from the East
Coast; 15 hours in the Midwest; 16
hours in the Mountain states; and 17
hours on the West Coast. The record
for a visual sighting stands at 15 hours,
32 minutes - an observation made by
S&T Contributing Editor Stephen James
O'Meara in May 1990.
If you live in the eastern half of the
U.S., you may not be able to meet the
challenge, but if you reside in the western
half you stand to see a rare delicacy. And
you can try again the following evening
when the crescent will be more fully illuminated
and even higher. Although you
won't be breaking any records, the Moon
will still be delightfully thin.
UT
29
20:25
17:14
14:04
10 10:53
13
16
19
21
24
27
7:43
4:32
1:21
22:11
19:00
15:49
18
30
PERSEUS
38
Algol
21
TRIANGULUM
34
http://www.skyandtelescope.org/algol http://skyandtelescope.org
Sky & Telescope - February 2024

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