07h48m06.468s, +50° 13′ 32.96″| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx[1] |
| XO-2S | |
| Right ascension | 07h48m 07.4814s[2] |
| Declination | +50° 13′ 03.2554″[2] |
| Apparent magnitude (V) | 11.12±0.03[3] |
| XO-2N | |
| Right ascension | 07h48m 06.4723s[4] |
| Declination | +50° 13′ 32.9206″[4] |
| Apparent magnitude (V) | 11.18±0.03[3] |
| Characteristics | |
| Spectral type | K0V + K0V[3] |
| Astrometry | |
| XO-2S | |
| Radial velocity (Rv) | 46.94±0.27[2] km/s |
| Proper motion (μ) | RA: −29.308(15) mas/yr[2] Dec.: −154.233(13) mas/yr[2] |
| Parallax (π) | 6.6721 ± 0.0151 mas[2] |
| Distance | 489 ± 1 ly (149.9 ± 0.3 pc) |
| Absolute magnitude (MV) | 5.74[5] |
| XO-2N | |
| Radial velocity (Rv) | 47.45±0.44[4] km/s |
| Proper motion (μ) | RA: −29.552(15) mas/yr[4] Dec.: −154.227(11) mas/yr[4] |
| Parallax (π) | 6.6588 ± 0.0158 mas[4] |
| Distance | 490 ± 1 ly (150.2 ± 0.4 pc) |
| Absolute magnitude (MV) | 5.74[5] |
| Details[6] | |
| XO-2S | |
| Mass | 0.98±0.05 M☉ |
| Radius | 1.02+0.09 −0.06 R☉ |
| Luminosity | 0.79±0.14 L☉ |
| Surface gravity (log g) | 4.420±0.094 cgs |
| Temperature | 5,325±37 K |
| Metallicity [Fe/H] | 0.32±0.08 dex |
| Rotation | 26.0±0.6 d |
| Rotational velocity (v sin i) | 1.5±0.3 km/s |
| Age | 7.1+2.5 −2.9 Gyr |
| XO-2N | |
| Mass | 0.96±0.05 M☉ |
| Radius | 0.998+0.033 −0.032 R☉ |
| Luminosity | 0.70±0.04 L☉ |
| Surface gravity (log g) | 4.43±0.10 cgs |
| Temperature | 5,290±18 K |
| Metallicity [Fe/H] | 0.37±0.07 dex |
| Rotation | 41.6±1.1 d |
| Rotational velocity (v sin i) | 1.07±0.09 km/s |
| Age | 7.8+1.2 −1.3 Gyr |
| Other designations | |
| |
| XO-2S: LSPM J0748+5013S, TYC 3413-210-1, GSC 03413-00210, 2MASS J07480748+5013032[7] | |
| XO-2N: BD+50 1471, LSPM J0748+5013N, TOI-1720, TIC 356473034, TYC 3413-5-1, GSC 03413-00005, 2MASS J07480647+5013328[8] | |
| Database references | |
| SIMBAD | XO-2S |
| XO-2N | |
XO-2 is a binary star system about 490 light-years (150 parsecs) away in the constellation Lynx. It consists of two components, XO-2N and XO-2S, both of which host planetary systems.[9]
This system is unusual in that the stars are not typically referred to as components A & B, but are designated based on their positions in the sky: XO-2N is the northern star and XO-2S is the southern star.
Both of the stars are slightly cooler than the Sun and are nearly identical to each other. The system has a magnitude of 11 and cannot be seen with the naked eye but is visible through a small telescope. These stars are also notable for their large proper motions.[7][8]
XO-2N and XO-2S have a separation of approximately 4,600 AU.[3]
There is one confirmed exoplanet orbiting XO-2N. XO-2Nb, which is classified as a hot Jupiter, was discovered by the XO Telescope using the transit method around XO-2N in 2007. It was initially the only known planet in the system and was referred to as XO-2b.[3] A long-period variation in the radial velocity of XO-2N was detected in 2015, which could be explained by either a second planet or a stellar activity cycle. The stellar activity explanation is considered more likely,[6] and is further supported by a 2024 study.[10]
Two planets were reported to orbit around XO-2S in 2014 using the radial velocity method. One of them is Jupiter-mass and another has a mass comparable to Saturn.[9] A 2024 study found evidence for a third, super-Jupiter mass planet around XO-2S.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.597±0.021 MJ | 0.03673(64) | 2.61585922(28) | <0.006 | 87.96+0.42 −0.34° |
1.019±0.031 RJ |
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥0.26±0.01 MJ | 0.1347±0.0025 | 18.220±0.001 | 0.15±0.02 | — | — |
| c | ≥1.38±0.05 MJ | 0.4737+0.0085 −0.0088 |
120.059±0.013 | 0.149±0.006 | — | — |
| d | ≥3.71+1.2 −0.51 MJ |
5.46+0.85 −0.40 |
4,696+1,133 −489 |
0.091+0.028 −0.018 |
— | — |
