Quadrans

Lalande's initial image of Quadrans mapped to Stellarium (Susanne M Hoffmann). In this case, the lines of RA,DEC in the historical map are used to anchor the star chart.

Fortin's 1795 edition of Flamsteed's celestial atlas in French does displays Quadrans in Draco

Quadrans is the name of the star 44 Boo (i Boo, SIMBAD). It was named by the IAU in 2025 to resemble the obsolete constellation Quadrans Muralis, which is preserved in the name of the Quadrantides meteor shower.

Etymology and History

the radiant of the Quadrantides meteor shower displayed in Stellarium (2025) with stars shown only brighter than 6.5 mag. The star closest to the current radiant marked.

In the late 18th century, the French astronomer Jean-Baptiste Fortin and the German astronomer Johann E. Bode published several translated and updated editions of Flamsteed's Atlas Coelestis. In the last version of the French edition 1795, the reviewer Jérôme Lalande introduced the new constellation "Quadrans Muralis" (Latinized by later Bode) or French "Le Mural", but drew it only one of the two maps were the area is included:

• 

  Lalande's Quadrans on Stellarium with the three brightest stars marked (Susanne M Hoffmann 2025).

The actual instrument that served as an inspiration for Lalande is still preserved in the Paris Observatory.

Mythology

no mythology

IAU Working Group Star Names

Lalande's Quadrans on Stellarium with the three brightest stars marked (Susanne M Hoffmann 2025).

The name was discussed and applied by the IAU WGSN in 2025.

Brightest Stars of the Historical Constellation

The brightest stars in the vicinity of Quadrans Muralis, in order of brightness are:

1. 44 Boo (HR 5618, HD 133640; V=4.76)
2. CL Dra (HR 5960, HD 143466; V=4.95)
3. BP Boo (HR 5857, HD 140728; V=5.51)
4. 47 Boo (HR 5627, HD 133962; V=5.57)
5. 39 Boo (HR 5538, HD 131041; V=5.69)
6. HR 5830 (HR 5830, HD 139798; V=5.75)
7. X Her (HD 144205; V=6.58).

The two brightest stars are notable bright stars in the solar neighbourhood: 44 Boo (d = 13 parsecs) and CL Dra (d = 34 parsecs). 44 Boo is a resolved multiple system. A having V=4.991±0.009 (ASCC-2.5) and its secondary (an unresolved W UMa contact binary) having V=6.002±0.008 (ASCC-2.5). So, considering the brightnesses of the component stars, CL Dra is brighter! (V=4.96 in Hipparcos, V=4.957±0.007 in Mermilliod 1991. However, CL Dra is only inside Bode's constellation area but not in Lalande's original image.

Note that in 2025 the radiant for the Quadrantid meteor shower is near RA, Dec = 230.2, +49.5 (ICRS, J2000; Jenniskens et al. 2016), which is in Bootes and closer to 44 Boo than CL Dra.

Confusions on Star Qualities

For CL Dra, SIMBAD gives a wrong magnitude; VSX registers it with 4.95±0.02 mag and as "delta Scuti"-type variable but this class has become obsolete as the variability is so small.

For 44 Boo, SIMBAD lists two components:

• A with V=4.991+-0.009 (ASCC-2.5) and
• B, an unresolved W UMa contact binary, with V=6.002+-0.008 (ASCC-2.5)

For A, it displays the "note": "Not recovered in Gaia DR3 (see I/350/gaiaedr3)". Some of the very brightest stars do not appear in Gaia DR3 (alpha Cen A and B are great examples). 44 Boo is a bit of an unusual triple system (at least) as both components seem to be binaries: A seems to be a spectroscopic binary, the B component is a W UMa system (perhaps the nearest contact binary to the Sun) with known RV orbit and more recent analysis including TESS data. 0It appears that Gaia DR2 successfully split the bright pair A and B and provided two entries, but Gaia DR3 barfed on A (no entry) and only provided information on the B.

Kirkpatrick+2024 has a long note on the confusion in the literature about which component is the contact binary:

"Component A is an SB1 (Duquennoy1991) but this is an SB1 due to the orbital motion of A around Ba-Bb (and it's not an SB2 because Ba-Bb is outside the slit). Component B is an EB (Samus2017). There appears to be a typo in Table 2 of Duquennoy1991 stating that it's the Aa-Ab system that has a 0.2678-day orbit period, but this is the value for Ba-Bb. Their own note to this table makes it clear that the system is only a triple. Nonetheless, this mistake seems to have propagated to Abt2006 and then to the WDS Notes. Soderhjelm1999 gives a total mass of 2.70±0.16 M_Sun. We use the measured/estimate spectral types to estimate individual types. Our total estimated mass of 2.61 M_Sun compares well to the Soderhjelm1999 total dynamical mass of 2.70 M_sun but less well to the Malkov2012 total dynamical mass of 2.190 M_sun."

Discussed Proposals

One proposal is to name the V=4.95 mag-star CL Dra. Another proposal could be to apply "Quadrans" to one star and "Muralis" to the other, e.g. "Quadrans" for 44 Boo (the primary of its triple) and "Muralis" for CL Dra, but with respect to other cultures who might want to name stars, WGSN name only one of them.

WGSN chose to name 44 Boo A "Quadrans".

Reference

• References (general)
• References (early modern)