9 Lacertae is a single star in the northern constellation Lacerta, located 172 light years away from Sun. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.64. This object is moving further from the Earth with a heliocentric radial velocity of +10 km/s.
This is an A-type main-sequence star with a stellar classification of A9VkA7mA6. This notation indicates it has the Hydrogen lines of an A9 star, the Calcium K line of an A7 star, and the metal lines of an A6. It is 513 million years old with a high projected rotational velocity of 105 km/s. The star has 1.59 times the mass of the Sun and about 2.1 times the Sun's radius. It is radiating 34.6 times the Sun's luminosity from its photosphere at an effective temperature of 7,614 K.
Epoch J2000 Equinox J2000
|Right ascension||22h 37m 22.41727s|
|Declination||+51° 32′ 42.4383″|
|Apparent magnitude (V)||4.64|
|Evolutionary stage||main sequence|
|B−V color index||0.254±0.006|
|Radial velocity (Rv)||+10.1±1.5 km/s|
|Proper motion (μ)|| RA: −51.83 mas/yr |
Dec.: −103.80 mas/yr
|Parallax (π)||19.00 ± 0.19 mas|
|Distance||172 ± 2 ly |
(52.6 ± 0.5 pc)
|Absolute magnitude (MV)||1.03|
|Surface gravity (log g)||3.77±0.14 cgs|
|Metallicity [Fe/H]||−0.20 dex|
|Rotational velocity (v sin i)||105 km/s|
Alpha Lacertae, Latinized from α Lacertae, is a single white-hued star in the constellation of Lacerta, located 103 light years from the Sun. It is the brightest star in Lacerta with an apparent visual magnitude of 3.76. The star is moving closer to the Earth with a heliocentric radial velocity of −4.5 km/s.This is an ordinary A-type main-sequence star with a stellar classification of A1 V, which indicates it is generating energy through hydrogen fusion at its core. It is around 400 million years old with a relatively high rate of spin, showing a projected rotational velocity of 128 km/s. The star has 2.2 times the mass of the Sun and 2.1 times the Sun's radius. It is radiating 28 times the Sun's luminosity from its photosphere at an effective temperature of 9,050 K.Alpha Lacertae has a visual companion, CCDM J22313+5017B, of spectral type A and apparent visual magnitude 11.8, approximately 36 arcseconds away. The companion is optical, a chance line-of-sight coincidence.Beta Lacertae
Beta Lacertae (Beta Lac, β Lacertae, β Lac) is the fourth-brightest star in the constellation of Lacerta. Based upon an annual parallax shift of 19.19 mas, it is 170 light years distant from Earth. At that distance, the visual magnitude is diminished by an extinction factor of 0.17 due to interstellar dust.This is an evolved G-type giant with an apparent visual magnitude of approximately 4.43. It is a red clump star and the primary component of a suspected binary system, with the pair having an angular separation of 0.2 arc seconds.Epsilon Cephei
Epsilon Cephei, Latinized from ε Cephei, is a star in the northern constellation of Cepheus. Based upon an annual parallax shift of 38.17 mas as seen from the Earth, it is located about 85 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 4.18.This is a yellow-white hued, F-type star with a stellar classification of F0 V (Sr II) or F0 IV. Thus it may either be an F-type main sequence star showing an abundance excess of strontium, or it could be a more evolved subgiant star. It is a Delta Scuti variable star that cycles between magnitudes 4.15 and 4.21 every 59.388 minutes. The star displays an infrared excess, indicating the presence of a debris disk with a temperature of 65 K orbiting at a radius of 62 AU. This dust has a combined mass equal to 6.6% of the Earth's mass.There is a faint companion star at an angular separation of 330±50 mas along a position angle of 90°±10°. This corresponds to a projected physical separation of 8.6±1.4 AU. The probability of a random star being situated this close to Epsilon Cephei is about one in a million, so it is most likely physically associated. If so, then the debris disk is probably circumbinary. The fact that this companion was not detected during the Hipparcos mission may indicate its orbit has a high eccentricity. The companion star has a K-band magnitude of 7.8 and is probably of class K8–M2.Iota Andromedae
Iota Andromedae (ι And, ι Andromedae) is a star in the constellation Andromeda. It has an apparent magnitude of +4.29 and is approximately 500 light years from Earth.Iota Andromedae is a B-type main sequence star with a stellar classification of B8 V. It is among the least variable stars observed during the Hipparcos mission.Kappa Andromedae
Kappa Andromedae (κ And, κ Andromedae) is the Bayer designation for a bright star in the constellation of Andromeda. Its apparent visual magnitude is 4.1. Based on the star's ranking on the Bortle Dark-Sky Scale, it is luminous enough to be visible from the suburbs and from urban outskirts, but not from brightly lit inner city regions. Parallax measurements made during the Hipparcos mission place it at a distance of approximately 168 light-years (52 parsecs) from Earth.
Kappa Andromedae has a stellar classification of B9 IVn, indicating that it is a subgiant star in the process of evolving away from the main sequence. It has 2.3 times the radius of the Sun and is spinning rapidly, with a projected rotational velocity of 176 km/s. The outer envelope of the star is radiating energy into space with an effective temperature of 11,361 K, producing a blue-white hue.Lambda Andromedae
Lambda Andromedae (λ And, λ Andromedae) is the Bayer designation for a binary star in the northern constellation of Andromeda. At an estimated distance of approximately 86.1 light-years (26.4 parsecs) from Earth, it has an apparent visual magnitude of +3.8. This is bright enough to be seen with the naked eye.
Lambda Andromedae is a single-lined spectroscopic binary with an orbital period of 20.5212 days. The spectrum of the primary matches a stellar classification of G8 III-IV, suggesting that it is an evolved star that lies part way between the subgiant and giant stages. The mass of this star is similar to the Sun, but it has expanded to around seven times the Sun's radius. It is radiating over 23 times the luminosity of the Sun from its outer envelope at an effective temperature of 4,800 K, giving it the characteristic yellow hue of a G-type star.
This is an RS Canum Venaticorum variable and its brightness varies by 0.225 magnitudes, reaching a maximum of 3.70, with a period of 54.2 days. Such variability is theorized to occur because of tidal friction, which results in chromospheric activity. However, the orbit of this system is nearly circular, so the cause of this system's variability remains uncertain. The X-ray luminosity of this star, as measured by the ROSAT satellite, is 2.95 × 1030 erg s−1.Pi1 Cygni
Pi¹ Cygni (π¹ Cygni, abbreviated Pi¹ Cyg, π¹ Cyg) is a binary star in the northern constellation of Cygnus. It is visible to the naked eye, having a combined apparent visual magnitude of 4.66. The distance to this system can be roughly gauged by its annual parallax shift of 1.89 mas, which yields a separation of around 1,700 light years from the Sun, give or take a hundred light years.
The two components are designated Pi¹ Cygni A (officially named Azelfafage , the traditional name for the system) and B.Pi2 Cygni
Pi2 Cygni, Latinized from π2 Cygni, is a triple star system in the northern constellation of Cygnus. It is visible to the naked eye about 2.5° east-northeast of the open cluster M39, having an apparent visual magnitude of 4.24. Based upon an annual parallax shift of 2.95 mas, it is located at a distance of roughly 1,100 light years from the Sun.
The inner pair of stars in this system form a single-lined spectroscopic binary with an orbital period of 72.0162 days and an eccentricity of 0.34. The primary, component A, is a B-type giant star with a stellar classification of B2.5 III. It is a Beta Cephei variable with an estimated 8.4 times the mass of the Sun and around 7.1 times the Sun's radius. The star is roughly 33 million years old and is spinning with a projected rotational velocity of 50 km/s. It is radiating 8,442 times the solar luminosity from its outer atmosphere at an effective temperature of around 20,815 K.
The third member of this system is a magnitude 5.98 star at an angular separation of 0.10 arc seconds along a position angle of 129°, as of 1996.Psi Andromedae
Psi Andromedae (ψ And, ψ Andromedae) is the Bayer designation for a triple star system in the northern constellation of Andromeda. The combined apparent visual magnitude of this system is 4.95. Based upon parallax measurements, is roughly 1,000 light-years (310 parsecs) from Earth, with 14% margin of error.The primary component has a stellar classification of G5 Ib, which matches the spectrum of an evolved bright giant star. It forms a pair with a star of type B9 with an unknown luminosity class separated by 0.28 arcseconds. A third component has a separation of 0.14 arcseconds. Details of the orbital arrangement remain uncertain.Rho Cassiopeiae
Rho Cassiopeiae (; ρ Cas, ρ Cassiopeiae) is a yellow hypergiant star in the constellation Cassiopeia. It is about 3,400 light-years (1,000 pc) from Earth, yet can still be seen by the naked eye as it is 500,000 times brighter than the Sun. On average it has an absolute magnitude of −9.5, making it visually one of the most luminous stars known. Its diameter measures between 400 and 500 times that of the Sun, approximately 627,000,000 kilometers, or about twice the size of the Earth's orbit.
Rho Cassiopeiae is a single star, and is categorized as a semiregular variable. As a yellow hypergiant, it is one of the rarest types of stars. Only around a dozen are known in the Milky Way, but it is not the only one in its constellation which also contains V509 Cassiopeiae.Sigma Cassiopeiae
Sigma Cassiopeiae (σ Cas, σ Cassiopeiae) is a binary star in the constellation Cassiopeia. It is approximately 5000 light years from Earth and has a combined apparent magnitude of +4.88.
The primary component, σ Cassiopeiae A, is a B2 subgiant with an apparent magnitude of +5.0. Its companion, σ Cassiopeiae B, is a B5 main sequence dwarf with an apparent magnitude of +7.1. The two stars are three arcseconds apart.Tau Cassiopeiae
Tau Cassiopeiae (τ Cassiopeiae) is a solitary, orange hued star in the northern constellation of Cassiopeia. It is bright enough to be seen with the naked eye, having an apparent visual magnitude of +4.86. Based upon an annual parallax shift of 18.75 mas as seen from Earth, this system is located about 174 light years from the Sun.
The spectrum of this star indicates it is an evolved, K-type giant star with a stellar classification of K1 IIIa. It is a suspected variable star of unknown type. Tau Cassiopeiae is 3.9 billion years old with about 1.44 times the mass of the Sun and 10 times the Sun's radius. It is radiating 40 times the Sun's luminosity from its expanded photosphere at an effective temperature of around 4,617 K.