BT Monocerotis was a nova, which lit up in the constellation Monoceros in 1939. It was discovered on a spectral plate by Fred L. Whipple on December 23, 1939. BT Monocerotis is believed to have reached mag 4.5, which would have made it visible to the naked eye, but that value is an extrapolation; the nova was not observed at peak brightness Its brightness decreased after the outbreak by 3 magnitudes in 182 days, making it a "slow nova". The light curve for the eruption had a long plateau period.
Mu Cassiopeiae, Latinized from μ Cassiopeiae, is a binary star system in the constellation Cassiopeia. This system shares the name Marfak with Theta Cassiopeiae, and the name was from Al Marfik or Al Mirfaq (المرفق), meaning "the elbow". It is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.16. The system is located at a distance of 25 light years from the Sun based on parallax, and is moving closer with a high radial velocity of −98 km/s. This star will move into the constellation Perseus around 5200 AD.
4 Cassiopeiae is a red giant in the northern constellation of Cassiopeia, located approximately 790 light-years away from the Sun. It is visible to the naked eye as a faint, red-hued star with a baseline apparent visual magnitude of 4.96. At the distance of this system, its visual magnitude is diminished by an extinction of 0.56 due to interstellar dust. This system is moving closer to the Earth with a heliocentric radial velocity of −39 km/s.
EW Aquarii, or HR 8102, is a variable star in the equatorial constellation of Aquarius. With an apparent visual magnitude that fluctuates around 6.47, it is a dim star near the lower limit of visibility to the naked eye. The star is located at a distance of approximately 439 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −39 km/s. The star is positioned near the ecliptic and thus is subject to lunar occultations. It may be a member of the Hyades Group.
HD 160342 is a star in the southern constellation of Ara. HD 160342 is its Henry Draper Catalogue designation. It has an apparent visual magnitude of 6.35 and, based upon parallax measurements, is approximately 960 light-years distant from Earth.
V394 Aurigae is a semi-regular variable star in the constellation Auriga. Its brightness varies between magnitudes 6.01 and 6.11, so it is faintly visible to the naked eye under ideal observing conditions. Koen and Eyer found that the star's brightness, as seen by Hipparcos, varies with a period of 3.9 days. Located around 730 light-years distant, V394 Aurigae shines with a luminosity approximately 1075 times that of the Sun and has a surface temperature of 3589 K.
QS Virginis is an eclipsing binary system approximately 163 light-years away from the Sun, forming a cataclysmic variable. The system comprises an eclipsing white dwarf and red dwarf that orbit each other every 3.37 hours.
22 Cygni is a binary star system in the northern constellation of Cygnus. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.95. The annual shift of 3.0 mas yields a distance estimate of around 1,070 light years. It is moving closer to the Earth with a heliocentric radial velocity of −15 km/s.
V1073 Scorpii is a variable star in the constellation Scorpius. It has a non-Greek Bayer designation of k Scorpii. The star has a blue-white hue and is visible to the naked eye with an apparent visual magnitude that fluctuates around +4.87. Parallax measurements yield a distance estimate of approximately 2,920 ly (896 pc) from the Sun, and it is drifting further away with a radial velocity of +7 km/s. It has an absolute magnitude of −6.8
Y Centauri or Y Cen is a semiregular variable star in the constellation of Centaurus.
UY Scuti (BD-12°5055) is a red supergiant star, located 5,900 light-years away in the constellation Scutum. It is also a pulsating variable star, with a maximum brightness of magnitude 8.29 and a minimum of magnitude 10.56, which is too dim for naked-eye visibility. It is considered to be one of the largest known stars, with a radius estimated at 909 solar radii, thus a volume of 750 million times that of the Sun. This estimate implies if it were placed at the center of the Solar System, its photosphere would extend past the orbit of Mars or even the asteroid belt.
BX Circini is a star in the constellation Circinus. Its variability was discovered in 1995, with its apparent magnitude ranging from 12.57 to 12.62 over a period of 2 hours 33 minutes. It is currently classified as a PV Telescopii variable star, but has been put forward as the prototype of a new class of pulsating star—the BX Circini variables—along with the only other known example, V652 Herculis. This class of star is rare, possibly because this is a brief stage of stellar evolution. Its mass has been calculated to be around 40 percent that of the Sun, but the radius is a few times larger than that of the Sun. The average surface temperature is high, and has been measured at 23,390 ± 90 K using optical spectra, but 1750 K cooler if analysing it in both the visual and ultraviolet. The temperature appears to vary by 3450 K.
EC 20058-5234 , is a star in the constellation Telescopium. With an apparent magnitude of 15.03, it's impossible to detect with the naked eye and requires a powerful telescope to be seen; this degenerate object is located 388 light years from the Solar System based on parallax.
U Vulpeculae is a variable and binary star in the constellation Vulpecula.
BO Carinae, also known as HD 93420, is an irregular variable star in the constellation Carina.
IX Carinae is a red supergiant and pulsating variable star of spectral type M2Iab in the constellation Carina. It is a member of the Carina OB1 association along the Carina Nebula.
BD Phoenicis is a variable star in the constellation of Phoenix. From parallax measurements by the Gaia spacecraft, it is located at a distance of 256 light-years from Earth. Its absolute magnitude is calculated at 1.5.
NY Virginis is a binary star about 1,940 light-years away. The primary belongs to the rare class of subdwarf B stars, being former red giants with their hydrogen envelope completely stripped by a stellar companion. The companion is a red dwarf star. The binary nature of NY Virginis was first identified in 1998, and the extremely short orbital period of 0.101016 d, together with brightness variability on the timescale of 200 seconds was noticed, resulting in the identification of the primary star as a B-type subdwarf in 2003. Under a proposed classification scheme for hot subdwarfs it would be class sdB1VII:He1. This non-standard system indicates that it is a "normal" luminosity for a hot subdwarf and that the spectrum is dominated by hydrogen rather than helium.
Kepler-429 is a variable subdwarf B star in the constellation Lyra, about 5,900 light years away.
HD 77887 is a solitary star located in the southern circumpolar constellation Volans. It has an apparent magnitude of 5.87, making it faintly visible to the naked eye if viewed under ideal conditions. The star is situated at a distance of about 760 light years but is receding with a heliocentric radial velocity of 12.6 km/s.
