Serpens is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda.
Iota Orionis is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly 1,340 light-years from the Sun.
Epsilon Aurigae is a multiple star system in the northern constellation of Auriga, the charioteer. It is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. The distance to the system is still a subject of debate, but data from the Gaia spacecraft puts its distance at around 3,300 light years from Earth.
W Sagittarii is a multiple star system star in the constellation Sagittarius, and a Cepheid variable star.
VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus. It is both a B[e] star and shell star. As a 5th magnitude star, it is visible to the naked eye under good observing conditions.
Sigma Orionis or Sigma Ori is a multiple star system in the constellation Orion, consisting of the brightest members of a young open cluster. It is found at the eastern end of the belt, south west of Alnitak and west of the Horsehead Nebula which it partially illuminates. The combined brightness of the component stars is magnitude 3.80.
Gamma Persei is a binary star system in the constellation Perseus. The combined apparent visual magnitude of the pair is +2.9, making it the fourth-brightest member of the constellation. The distance to this system is of roughly 221 light-years with a 1% margin of error. About 4° to the north of Gamma Persei is the radiance point for the annual Perseid meteor shower.
HR Carinae is a luminous blue variable star located in the constellation Carina. It is surrounded by a vast nebula of ejected nuclear-processed material because this star has a multiple shell expanding atmosphere. This star is among the most luminous stars in the Milky Way. It has very broad emission wings on the Balmer lines, reminiscent from the broad lines observed in the spectra of O and Wolf–Rayet stars. A distance of 5 kpc and a bolometric magnitude of −9.4 put HR Car among the most luminous stars of the galaxy.
S Monocerotis, also known as 15 Monocerotis, is a massive multiple and variable star system located in the constellation Monoceros. It is the brightest star in the Christmas Tree open cluster in the area catalogued as NGC 2264.
V1429 Aquilae is a candidate luminous blue variable multiple star system located in the constellation of Aquila. It is often referred to by its Mount Wilson Observatory catalog number as MWC 314. It is a hot luminous star with strong emission lines in its spectrum.
A Double Periodic Variable (DPV) is a type of binary star. As the name implies, the systems vary in brightness not only due to eclipses of one star by the other, but also on a cycle of roughly 33 times longer than the orbit. The star gaining mass from the other has a thick disk of material surrounding it, and the systems apparently lose mass cyclically into the interstellar medium over time. The cause for the secondary longer variability still is not established, but it has been proposed to be linked to a magnetic dynamo in the donor star. A famous example is β Lyrae. The stars are rare, with 21 systems found in the Galaxy and more than 170 in the Magellanic Clouds.
AC Herculis, is an RV Tauri variable and spectroscopic binary star in the constellation of Hercules. It varies in brightness between apparent magnitudes 6.85 and 9.0.
WR 30a is a massive spectroscopic binary in the Milky Way galaxy, in the constellation Carina. The primary is an extremely rare star on the WO oxygen sequence and the secondary a massive class O star. It appears near the Carina Nebula but is much further away.
XZ Andromedae is a binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 9.91, but drops down to 12.45 every 1.357 days. Its variability matches the behaviour of Algol variable stars.
AI Phoenicis is a variable star in the constellation of Phoenix. An Algol-type eclipsing binary, its apparent magnitude is constant at 8.58 for most of the time, sharply dropping to 9.35 during primary eclipse and to 8.89 during secondary eclipse. The system's variability was discovered by W. Strohmeier in 1972. From parallax measurements by the Gaia spacecraft, the system is located at a distance of 560 light-years from Earth, in agreement with earlier estimates based on its luminosity.
HD 139319 is a ternary system composed of the binary Algol variable star known as TW Draconis, and a main-sequence companion star at a separation of 3 arcseconds. The system lies in the constellation of Draco about 540 light years away.
TX Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major. With a combined apparent visual magnitude of 6.97, the system is too faint to be readily viewed with the naked eye. The pair orbit each other with a period of 3.063 days in a circular orbit, with their orbital plane aligned close to the line of sight from the Earth. During the primary eclipse, the net brightness decreases by 1.74 magnitudes, while the secondary eclipse results in a drop of just 0.07 magnitude. TX UMa is located at a distance of approximately 780 light years from the Sun based on parallax measurements, but is drifting closer with a mean radial velocity of −13 km/s.
CV Serpentis is a binary star system in the equatorial constellation of Serpens. It is a detached eclipsing binary with an orbital period of 29.7 days. The system includes a Wolf–Rayet (WR) star with the identifier WR 113. The system is located at a distance of approximately 6,700 light years from the Sun based on parallax measurements. It is a member of the Serpens OB2 association of co-moving stars.
VV Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated VV UMa. It is a variable star system with a brightness that cycles around an apparent visual magnitude of 10.19, making it too faint to be visible to the naked eye. The system is located at a distance of approximately 1,500 light years based on parallax measurements.
RS Sagittarii is an eclipsing binary star system in the southern constellation of Sagittarius, abbreviated RS Sgr. It is a double-lined spectroscopic binary with an orbital period of 2.416 days, indicating that the components are too close to each other to be individually resolved. The system has a combined apparent visual magnitude of 6.01, which is bright enough to be faintly visible to the naked eye. During the primary eclipse the brightness drops to magnitude 6.97, while the secondary eclipse is of magnitude 6.28. The distance to this system is approximately 1,420 light years based on parallax measurements.
