LTT 3780
LTT 3780, also known as TOI-732 or LP 729-54, is the brighter component of a wide visual binary star system in the constellation Hydra. This star is host to a pair of orbiting exoplanets. Based on parallax measurements, it is located at a distance of 72 light years from the Sun. LTT 3780 has an apparent visual magnitude of 13.07, requiring a telescope to view.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 10h 18m 35.137s |
| Declination | −11° 43′ 00.24″ |
| Apparent magnitude (V) | 13.07±0.015 |
| Characteristics | |
| Spectral type | M3.5 V + M5.0 V |
| Apparent magnitude (B) | 14.678 |
| Apparent magnitude (G) | 11.8465±0.0005 |
| Apparent magnitude (J) | 9.007±0.030 |
| Astrometry | |
| Proper motion (μ) | RA: −341.537 mas/yr Dec.: −247.747 mas/yr |
| Parallax (π) | 45.3972 ± 0.0301 mas |
| Distance | 71.85 ± 0.05 ly (22.03 ± 0.01 pc) |
| Absolute magnitude (MV) | 11.36±0.02 |
| Position (relative to LTT 3780) | |
| Component | LP 729-55 |
| Epoch of observation | J2015.5 |
| Angular distance | 15.81±0.150″ |
| Position angle | 96.9±0.2° |
| Projected separation | 348±3 AU |
| Details | |
| LTT 3780 | |
| Mass | 0.401±0.012 M☉ |
| Radius | 0.374±0.011 R☉ |
| Luminosity | 0.167±0.003 L☉ |
| Surface gravity (log g) | 4.896±0.029 cgs |
| Temperature | 3,331±157 K |
| Metallicity [Fe/H] | 0.09±0.16 dex 0.28+0.11 −0.13 dex |
| Rotation | 104±15 |
| Rotational velocity (v sin i) | < 1.3 km/s |
| Age | 5 (assumed) Gyr |
| LP 729-55 | |
| Mass | 0.136±0.004 M☉ |
| Radius | 0.173±0.005 R☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of LTT 3780 presents as a small M-type main-sequence star, a red dwarf, with a stellar classification of M3.5 V. It is spinning very slowly, with a rotation period of 104 days. The abundance of iron, an indicator of the star's metallicity, appears higher than in the Sun. The star is inactive, showing a negligible level of magnetic activity in its chromosphere. It has about 40% of the mass and 37% of the radius of the Sun. The star is radiating just 17% of the Sun's luminosity from its photosphere at an effective temperature of 3,331.
Collectively designated LDS 3977, the two stars in this system share a common proper motion and have an angular separation of 15.8″, which corresponds to a (physical) projected separation of 348 AU. At this separation, the orbital period would be ~9,100 years. The fainter member is a red dwarf with a class of M5.0 V. It has 14% of the mass of the Sun and 17% of the Sun's radius.