Leo Minor
“The Little Lion” · Northern · best around April evenings
Real star positions and magnitudes (HYG database via D3-Celestial, BSD-3). Lines are the conventional stick figure; north is up.
The story
A small 17th-century filler constellation between the Great Bear's paws and Leo. Quirk: due to a cataloguing slip it has no star labeled Alpha.
How to find it
The dim triangle above Leo.
✦ What lives inside it
The deep dive
Researched for the Atlas from Wikipedia — Leo Minor (11,680 characters read) · updated Sep 20, 2026
01 A constellation born from an astronomer's gap-filling
Leo Minor exists because Johannes Hevelius looked at a blank stretch of sky and decided something ought to live there. In 1687 he outlined ten new constellations in his star atlas Firmamentum Sobiescianum, and Leo Minor was one of them. He included 18 of its objects in the accompanying Catalogus Stellarum Fixarum, choosing the name Leo Minor — or Leo Junior — precisely because the region sits between two beastly neighbours, Leo the Lion to the south and Ursa Major the Great Bear to the north. The region was not entirely ignored before him: the classical astronomers Aratus and Ptolemy had noticed the stars there, but Ptolemy simply classified them as amorphōtoi, meaning they belonged to no constellation outline, listing them informally within Leo. Hevelius gave them an identity. Over a century and a half later, in 1845, English astronomer Francis Baily revised Hevelius's catalogue and assigned Greek Bayer letters to stars bright enough to deserve them — which is how Beta Leonis Minoris acquired its designation. Richard Proctor tried to rename the whole figure Leaena, meaning "the Lioness," in 1870, arguing shorter names worked better on crowded charts, but the name never stuck.
02 Why Leo Minor has no Alpha star
One of the small oddities of Leo Minor is that it has a Beta but no Alpha. The blame falls on Francis Baily, who in 1845 set about assigning Bayer letters to the constellation's brighter stars but appears to have made a simple clerical error, allocating a Greek letter to only one star — Beta — and leaving the brightest star, 46 Leonis Minoris, with only a Flamsteed number. Whether Baily intended to designate 46 Leonis Minoris as Alpha remains genuinely unclear; he recognised both Beta and 46 Leonis Minoris as sufficiently bright in his catalogue, but he died before revising his proofs, and the gap was never corrected. To add to the tangle, the name Praecipua now attached to 46 Leonis Minoris was originally applied to the different star 37 Leonis Minoris by Giuseppe Piazzi in his 1814 Palermo Catalogue — Piazzi had incorrectly assessed 37 Leonis Minoris as the brighter of the two. The historian R. H. Allen later connected the name Praecipua to 46 Leonis Minoris, and subsequent astronomers simply repeated the error. Meanwhile, Johann Elert Bode catalogued the same star as o Leonis Minoris, a label later misread as Omicron — adding yet another layer to what is, for such a faint constellation, a surprisingly tangled nomenclature.
03 Arabic gazelles, a pond, and Chinese court officials
Long before Hevelius put his quill to these stars, other cultures had already woven them into sky stories of their own. German astronomer Christian Ludwig Ideler found evidence that the stars of Leo Minor had been called Al Thibā' wa-Aulāduhā — "Gazelle with her Young" — on a thirteenth-century Arabic celestial globe recovered by Cardinal Stefano Borgia and housed in Borgia's museum at Velletri. Arabist Friedrich Wilhelm Lach offered a different reading, suggesting the stars were instead seen as Al Haud, "the Pond," into which the gazelle jumps — a complementary image rather than a contradictory one, since the two names may describe related parts of the same scene. Chinese astronomy carved the region into several distinct administrative figures. The stars Beta, 30, 37, and 46 Leonis Minoris formed Neiping, interpreted as a "Court of Judge or Mediator" or alternatively as Shi, meaning "Court Eunuch." In some configurations those same stars merged with stars of neighbouring Leo to outline a large celestial dragon or a State Chariot. A separate line of four stars was called Shaowei, representing four Imperial advisors, though its exact boundaries remain uncertain and may have sprawled across Leo Minor, Leo, or adjacent regions.
04 The brightest star and its misleading name Deeper
The star that actually rules Leo Minor is 46 Leonis Minoris, known by the proper name Praecipua — however erroneously that name was attached. At magnitude 3.8 it is an orange giant of spectral class K0III, and its warm colour becomes clearly apparent through even modest binoculars. It sits 95 light-years, or 29 parsecs, from Earth and outshines the Sun by roughly 32 times while stretching 8.5 times the Sun's diameter. Its orange giant companion in the brightness rankings, Beta Leonis Minoris, is a binary system 154 light-years away. The primary is a spectral class G9III giant with about double the Sun's mass, 7.8 times its radius, and 36 times its luminosity. A yellow-white main-sequence star of spectral type F8 orbits between 0.1 and 0.6 arcseconds away — a separation tiny enough to challenge most amateur instruments — completing one orbit around their shared centre of gravity every 38.62 years. The third-brightest member of the constellation, 21 Leonis Minoris, is a white main-sequence star of spectral type A7V and average magnitude 4.5, situated about 98 light-years away. It spins so fast — completing one full rotation in less than 12 hours — that it is very likely noticeably flattened at its poles, and it belongs to the class of Delta Scuti pulsating variables used in asteroseismology studies.
05 A dwarf nova that erupts every few weeks Deeper
Tucked inside Leo Minor's faint borders is SX Leonis Minoris, a dwarf nova of the SU Ursae Majoris type identified in 1994. The system consists of a white dwarf and a donor star locked in an orbit so tight they complete a full revolution every 97 minutes. The white dwarf continuously siphons material from its companion onto an accretion disc, heating that disc to somewhere between 6,000 and 10,000 Kelvin. When enough material accumulates, the disc becomes unstable and the system erupts, brightening to magnitude 13.4 before subsiding back to a quiescent magnitude of 16.8 — a change of more than three magnitudes, or roughly a factor of fifteen in brightness. These outbursts recur every 34 to 64 days. Leo Minor also hosts a second dwarf nova, RZ Leonis Minoris, which brightens from around magnitude 17 to magnitude 14.2. What makes RZ Leonis Minoris especially notable is that it erupts at shorter intervals than other dwarf novae of its type, making it an outlier even within an already energetic class of objects. Both systems are targets for variable-star observers willing to work near the limits of moderate amateur telescopes.
06 The most stable clock in the sky Deeper
Among Leo Minor's strangest residents is G 117-B15A, also catalogued as RY Leonis Minoris — a pulsating white dwarf glowing at a faint apparent magnitude of 15.5. What sets it apart is the extraordinary regularity of its pulsations. The star beats with a period of approximately 215 seconds, and that period is lengthening by only one second every 8.9 million years. That glacial drift is caused by the white dwarf slowly cooling over time — a predictable, physics-driven process. Because of this near-perfect regularity, G 117-B15A has been proposed as the most stable celestial clock yet identified. The star is estimated to be around 400 million years old. Its stability makes it a valuable laboratory: by tracking the tiny drift in its pulse period with enough precision, astronomers can measure the white dwarf's cooling rate directly and, in principle, constrain the properties of particles like axions that might carry energy away from stellar interiors. At magnitude 15.5 it lies well beyond binoculars or small telescopes, but its scientific importance far outweighs its visual modesty.
07 Hanny's Voorwerp: a fossil quasar's light echo
In 2007, Dutch school teacher Hanny van Arkel was volunteering for the Galaxy Zoo citizen-science project when she noticed a vivid, ghostly blob near the spiral galaxy IC 2497 on one of the survey images. The object she found — quickly named Hanny's Voorwerp, Dutch for "Hanny's Object" — turned out to be one of the most unusual deep-sky objects known. It lies near IC 2497, which sits roughly 650 million light-years away, and the voorwerp itself is approximately the same size as the entire Milky Way. Within it sits a hole 16,000 light-years across. The leading explanation is that the voorwerp is a light echo: it is gas that was ionised and lit up by a powerful quasar at the heart of IC 2497, and it continues to glow even though the quasar may have switched off as recently as 200,000 years ago. Because light travels at a finite speed, the gas is still responding to radiation that left the now-quiet nucleus long before the quasar fell silent. The voorwerp thus preserves a record of activity that the galaxy's core no longer displays — a forensic clue written in glowing gas across hundreds of thousands of light-years.
08 Interacting galaxies and a supernova impostor Deeper
Leo Minor punches above its weight in peculiar galaxies. NGC 3432, located 42 million light-years away and seen almost perfectly edge-on from Earth, measures 6.8 by 1.4 arcminutes at an apparent magnitude of 11.7, and is receding from the Solar System at 616 kilometres per second. It carries tidal filaments and vigorous star formation intense enough to earn it a place in Halton Arp's Atlas of Peculiar Galaxies. In 2000 a star within it brightened to magnitude 17.4, subsequently identified as a luminous blue variable behaving as a supernova impostor — a star energetic enough to mimic a supernova without actually destroying itself. At least two pairs of interacting galaxies also populate the constellation. Arp 107 is a merging pair 450 million light-years distant. NGC 3395 and NGC 3396 — a spiral and an irregular barred spiral respectively — are interacting and lie 1.33 degrees southwest of 46 Leonis Minoris. The starburst barred spiral NGC 3504 hosted genuine supernovae in both 1998 and 2001. For observers with moderate apertures, the constellation offers an unusually rich collection of disturbed, merging, and star-forming systems concentrated in a small patch of sky.
09 A meteor shower with a 300-year-old comet parent
Leo Minor lends its name to a minor but real meteor shower, the Leonis Minorids. It was discovered by Dick McCloskey and Annette Posen of the Harvard Meteor Program in 1959, and its radiant lies within the constellation's borders. The shower peaks between October 18 and October 29 each year and is visible only from the Northern Hemisphere. Its parent body is the long-period comet C/1739 K1, also known as Zanotti, a comet observed back in 1739 — meaning the meteor stream has been traced to debris shed by a comet documented nearly three centuries ago. As long-period comets go, Zanotti visits the inner Solar System only rarely, but streams of particles it has shed over many orbits continue to cross Earth's path each autumn. The shower is classified as minor, so observers should not expect dramatic rates, but its historical pedigree and its connection to this obscure comet give it a certain appeal for dedicated meteor watchers willing to spend a cold October night under dark skies.
10 Two planetary systems hiding in a faint field Deeper
Despite its modest profile, Leo Minor contains at least two confirmed planetary systems. HD 87883 is an orange dwarf of spectral type K0V at magnitude 7.57, located 18 parsecs from Earth. Its diameter is about three quarters that of the Sun, and it is only 31 percent as luminous. A planet roughly 1.78 times the mass of Jupiter orbits it every 7.9 years, and the system may harbour additional smaller planets. HD 82886, also known by the proper name Illyrian, is a yellow dwarf of spectral type G0 at visual magnitude 7.63. In 2011, astronomers announced the discovery of a planet 1.3 times Jupiter's mass orbiting with a period of 705 days — just under two Earth years. Both host stars are too faint to see with the naked eye but are accessible to binoculars or small telescopes, offering observers the quiet satisfaction of looking at a sun around which a giant world is in motion. Neither system is currently known to host a terrestrial planet in a habitable zone, but the presence of at least one giant planet in each leaves open the question of what else might be orbiting further in.
11 Long-period variables and a red giant menagerie Deeper
Among the faint stars of Leo Minor lurk several long-period variable red giants that reward patient observers. R Leonis Minoris is a Mira variable of spectral type ranging from M6.5e to M9.0e, swinging between magnitudes 6.3 and 13.2 over a period of 372 days — a brightness change of roughly a factor of 500 from peak to minimum, enough to pass from easy binocular visibility to invisibility without optical aid. S Leonis Minoris, also a Mira, varies between magnitudes 8.6 and 13.9 over 234 days, while the semiregular variable U Leonis Minoris ranges from magnitude 10.0 to 13.3 over approximately 272 days. All three are red giants, and all sit near the faint limit that makes locating them in a relatively starless field genuinely challenging for amateur astronomers. The constellation also includes 10 and 11 Leonis Minoris, yellow giants of spectral type G8III that are RS Canum Venaticorum variables. The brighter of the two, 10 Leonis Minoris, varies by only 0.012 magnitude over 40.4 days, while 11 Leonis Minoris varies by 0.033 magnitude over 18 days and carries a faint red dwarf companion of spectral type M5V at magnitude 13.0.