Castor is the second-brightest object in the zodiac constellation of Gemini. It has the Bayer designation α Geminorum, which is Latinised to Alpha Geminorum and abbreviated Alpha Gem or α Gem. With an apparent visual magnitude of 1.58, it is one of the brightest stars in the night sky. Castor appears singular to the naked eye, but it is actually a sextuple star system organized into three binary pairs. Although it is the 'α' (alpha) member of the constellation, it is fainter than 'β' (beta) Geminorum, Pollux.
Epsilon Geminorum or ε Geminorum, formally named Mebsuta, is a star in the constellation of Gemini, on the outstretched right 'leg' of the twin Castor. The apparent visual magnitude of +3.06 makes it one of the brighter stars in this constellation. The distance to this star is determined at 860 light-years.
Eta Geminorum, formally named Propus, is a triple star system in the constellation of Gemini. It is a naked-eye variable star around 380 light years from the Sun.
Mu Geminorum or μ Geminorum, formally named Tejat, is a single star in the northern constellation of Gemini. From parallax measurements obtained during the Hipparcos mission, it is roughly 230 light-years distant from the Sun. The position of the star near the ecliptic means that it is subject to lunar occultations.
3 Aquarii is a variable star in the equatorial constellation of Aquarius. 3 Aquarii is the Flamsteed designation; it also bears the Bayer designation k Aquarii and the variable star designation EN Aquarii. With a mean apparent visual magnitude of 4.429, it is visible to the naked eye in dark skies. It has an annual parallax shift of 5.57 milliarcseconds with a 5% margin of error, which translates to a physical distance of around 590 light-years from Earth.
1 Cancri is a single star in the zodiac constellation of Cancer, positioned near the border with Gemini at a distance of around 467 light years from the Sun. It is barely visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.97. The object is moving further from the Earth with a heliocentric radial velocity of +14 km/s.
ω2 Cancri is a star in the zodiac constellation Cancer, located around 810 light years away from the Sun. It has the Flamsteed designation 4 Cancri; ω2 Cancri is the Bayer designation, which is Latinised to omega2 Cancri and abbreviated to ω2 Cnc or omega2 Cnc. The star is near the lower limit of visibility to the naked eye, having an apparent visual magnitude of 6.32. It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s. The position of this star near the ecliptic means it is subject to lunar occultations.
Lambda Geminorum, Latinized from λ Geminorum, is a candidate multiple star system in the constellation Gemini. It is visible to the naked eye at night with a combined apparent visual magnitude of 3.57. The distance to this system is 101 light years based on parallax, and it is drifting closer with a radial velocity of –7.4 km/s. It is a member of what is suspected to be a trailing tidal tail of the Hyades Stream.
Tau Geminorum, Latinized from τ Geminorum, is a star in the northern zodiac constellation of Gemini. It has the apparent visual magnitude of +4.42, making it visible to the naked eye under suitably good seeing conditions. This star is close enough to the Earth that its distance can be measured using the parallax technique, which yields a value of roughly 392 light-years.
40 Aquarii is a star in the equatorial constellation of Aquarius. 40 Aquarii is its Flamsteed designation; it was too faint to be included in the Bright Star Catalogue. The brightness of this star is below the normal limit for visibility with the naked eye, having an apparent visual magnitude of 6.93. Based upon parallax measurements, it is located about 726 light-years away from the Sun. It is moving closer to the Earth with a heliocentric radial velocity of -3 km/s. 40 Aquarii is positioned near the ecliptic and thus is subject to lunar occultations.
Rho Geminorum is a star system that lies 59 light-years away in the constellation of Gemini, about 5 degrees west of Castor. The system consists of a primary bright enough to be seen with the naked eye, a faint secondary which has rarely been observed even professionally, and a distant, somewhat bright tertiary which requires telescopic equipment for observation.
RX Telescopii is an irregular variable star in the constellation Telescopium. It has a maximum magnitude of 6.45 and a minimum magnitude 7.47. It is a red supergiant with a spectral type of M3Iab, indicating the star is an intermediate-size luminous supergiant star.
X Cancri is a variable star in the northern constellation of Cancer. It has a red hue and is visible to the naked eye at its brightest. The distance to this object is approximately 1,860 light years based on parallax measurements, but is drifting closer with a radial velocity of −5 km/s. It lies very close to the ecliptic and so is subject to lunar occultations.
3 Geminorum is a blue supergiant star in the constellation Gemini. It is a small amplitude pulsating variable and a close double star, with a mean combined apparent visual magnitude of about 5.7.
TV Geminorum is a variable red supergiant in the constellation Gemini. Its visual magnitude varies from 6.3 to 7.5.
6 Geminorum is a variable star in the zodiac constellation of Gemini, located roughly 5,800 light years away from the Sun. It has the variable star designation BU Geminorum; 6 Geminorum is the Flamsteed designation. At its brightest this reddish hued star is barely visible to the naked eye but is readily visible with binoculars, found southeast of M 35, just to the south of WY Geminorum. It is moving further from the Earth with a heliocentric radial velocity of +27 km/s. The star is a member of the Gemini OB1 association.
HD 166006, also known as HR 6778, is a solitary orange-hued star located in the southern constellation Telescopium. It has an apparent magnitude of 6.07, making it barely visible to the naked eye. Based on Gaia DR2 parallax measurements, the object is located 582 light years away. It is currently approaching the Solar System with a somewhat constrained heliocentric radial velocity of −15 km/s.
HD 114533, also known as HR 4976, is a solitary star located in the southern circumpolar constellation Chamaeleon. It has an apparent magnitude of 5.84, making it faintly visible to the naked eye. The system is located relatively far at a distance of roughly 2,100 light years based on Gaia DR3 parallax measurements but is drifting closer with a heliocentric radial velocity of −18 km/s. At its current distance, HD 114533A's brightness is diminished by 0.74 magnitudes due to interstellar dust. It has an absolute magnitude of −2.0.
72 Tauri is a possible binary star in the zodiac constellation of Taurus. It is faintly visible to the naked eye with an apparent visual magnitude of +5.5, although only 0.29° from the brighter υ Tauri. Based upon an annual parallax shift of 7.9 mas seen from Earth, it is around 410 light years from the Sun.
HD 37320 is a star located in the constellation Orion. It is an evolved blue giant star, based on its spectral type of B8III. The distance to HD 37320 is calculated at 285.5 parsecs, based on a parallax from Gaia EDR3. The apparent magnitude of the star is 5.852, which is above the limiting magnitude for naked-eye vision (6.5m), making it faintly visible to the naked eye.
