| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 08m 17.30243s[2] |
| Declination | +49° 27′ 29.3993″[2] |
| Apparent magnitude (V) | 5.26[3](5.29 to 5.38)[4] |
| Characteristics | |
| Spectral type | M1.5III[5] |
| U−Bcolor index | +1.92[6] |
| B−Vcolor index | +1.637±0.010[3] |
| Variable type | Lb[4] |
| Astrometry | |
| Radial velocity (Rv) | −13.92±0.06[3] km/s |
| Proper motion (μ) | RA: −58.584[2]mas/yr Dec.: 59.801[2]mas/yr |
| Parallax (π) | 4.6635±0.1756 mas[2] |
| Distance | 700 ± 30 ly (214 ± 8 pc) |
| Absolute magnitude (MV) | −0.87[3] |
| Details | |
| Mass | 0.8-2.6[7] M☉ |
| Radius | 74+10 −12[2] R☉ |
| Luminosity | 1,114±48[2] L☉ |
| Temperature | 3,889+379 −248[2] K |
| Other designations | |
| 13 Boo,CF Boo,BD+50°2047,FK5 3124,GC 19095,HD 123782,HIP 69068,HR 5300,SAO 44905,CCDM 14082+4927,WDS 14083+4927[8] | |
| Database references | |
| SIMBAD | data |
13 Boötis is a solitary[9]variable star in the northernconstellation ofBoötes, and is positioned near the western constellation border withUrsa Major. In 1977 it was given thevariable star designationCF Boötis,[10] often abbreviated CF Boo, while13 Boötis is the star'sFlamsteed designation. This star has a reddish hue and is faintly visible to thenaked eye with anapparent visual magnitude that fluctuates around 5.26.[3] It is located at a distance of approximately 700 light years from theSun based onparallax, but is drifting closer with aradial velocity of −14 km/s.[3]
The variability of the brightness of 13 Boötis was announced byJoel Stebbins andCharles Morse Huffer in 1928, based on observations made atWashburn Observatory.[11] This is an agingred giant star on theasymptotic giant branch[12] with astellar classification of M1.5III,[5] which is interpreted bystellar evolutionary models to mean it has exhausted the supply of hydrogen at itscore then cooled and expanded off themain sequence. It is classified as aslow irregular variable of the Lb type, and its brightness has been observed to vary from +5.29 down to +5.38.[4] The star has ~74 times the girth of the Sun and is radiating 1,114 times the Sun's luminosity from its swollenphotosphere at aneffective temperature of 3,889 K.[2]
There is a magnitude 11.05visual companion located at anangular separation of76.40 arcseconds from the brighter star, along aposition angle of 270°. This was first reported byWilliam Herschel in 1783.[13]
In 1991, Duquennoy & Mayor[14] reported the possible presence of a low-mass object (of likelysubstellar nature) orbiting the red giant 13 Bootis. They set a minimum mass of 30 times that ofJupiter (likely abrown dwarf) and estimated an orbital period of 1.35 years. So far there has been no confirmation about the presence a substellar object.
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b(unconfirmed) | ≥30MJ | ≥1.25 | 494 | 0.21 | — | — |
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