| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 10h 18m 35.137s [1] |
| Declination | −11° 43′ 00.24″ [1] |
| Apparent magnitude (V) | 13.07±0.015 [2] |
| Characteristics | |
| Spectral type | M3.5 V + M5.0 V [3] |
| Apparent magnitude (B) | 14.678 |
| Apparent magnitude (G) | 11.8465±0.0005 [2] |
| Apparent magnitude (J) | 9.007±0.030 [2] |
| Astrometry | |
| Proper motion (μ) |
RA: −341.537
mas/
yr
[1] Dec.: −247.747 mas/ yr [1] |
| Parallax (π) | 45.3972 ± 0.0301 mas [1] |
| Distance | 71.85 ± 0.05
ly (22.03 ± 0.01 pc) |
| Absolute magnitude (MV) | 11.36±0.02 [2] |
| Position (relative to LTT 3780) [3] | |
| 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 [2] M☉ |
| Radius | 0.374±0.011 [2] R☉ |
| Luminosity | 0.167±0.003 [3] L☉ |
| Surface gravity (log g) | 4.896±0.029 [2] cgs |
| Temperature | 3,331±157 [2] K |
| Metallicity [Fe/H] | 0.09±0.16 dex
[3] 0.28+0.11 −0.13 [2] dex |
| Rotation | 104±15 [2] |
| Rotational velocity (v sin i) | < 1.3 [2] km/s |
| Age | 5 (assumed) [3] Gyr |
| LP 729-55 | |
| Mass | 0.136±0.004 [2] M☉ |
| Radius | 0.173±0.005 [2] R☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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, [2] requiring a telescope to view.
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. [2] The abundance of iron, an indicator of the star's metallicity, appears higher than in the Sun. [3] The star is inactive, showing a negligible level of magnetic activity in its chromosphere. [2] 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. [2]
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. [3] At this separation, the orbital period would be ~9,100 years. [2] The fainter member is a red dwarf with a class of M5.0 V. [3] It has 14% of the mass of the Sun and 17% of the Sun's radius. [2]
Planetary system
In 2020, an analysis carried out by a team of astronomers led by astronomer Ryan Cloutier of the TESS project confirmed the existence of two planets on mildly eccentric orbits, the inner being a super-Earth and the outer a small gas planet about half the mass of Uranus.
| Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 2.34+0.24 −0.23 M🜨 |
0.01203+0.00054 −0.00053 |
0.77±0.001 | 0.064+0.075 −0.046 |
85.9 ° | 1.35±0.06 R🜨 |
| c | 6.29+0.63 −0.61 M🜨 |
0.0762±0.0034 | 12.252131+0.000072 −0.000064 |
0.115+0.07 −0.065 |
89.08 ° | 2.42±0.1 R🜨 |
See also
References
- ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e f g h i j k l m n o p q r s t Cloutier, Ryan; et al. (2020). "A pair of TESS planets spanning the radius valley around the nearby mid-M dwarf LTT 3780". The Astronomical Journal. 160 (1): 3. arXiv: 2003.01136. Bibcode: 2020AJ....160....3C. doi: 10.3847/1538-3881/ab91c2. S2CID 211817805.
- ^ a b c d e f g h i Nowak, G.; et al. (2020). "The CARMENES search for exoplanets around M dwarfs. Two planets on the opposite sides of the radius gap transiting the nearby M dwarf LP 729-54". Astronomy & Astrophysics. A173: 642. arXiv: 2003.01140. Bibcode: 2020A&A...642A.173N. doi: 10.1051/0004-6361/202037867. S2CID 211818198.
- ^ "LTT 3780". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-03-06.