| 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 | 3.10+6.20 −0.98[4] 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[edit]
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.
LTT 3780 c[edit]
Astronomers utilizing the Gemini South 8.1-meter telescope performed an atmospheric survey of LTT 3780 c through high-resolution transmission spectroscopy. From observations during a single transit, they detected tentative signs of methane in the atmosphere but found no traces of ammonia, even though it is highly detectable in a cloud-free, hydrogen-rich atmosphere.[6]
| 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[edit]
References[edit]
- ^ 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 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.
- ^ Bonfanti, A.; et al. (2024). "Characterising TOI-732 b and c: New insights into the M-dwarf radius and density valley". Astronomy & Astrophysics. 682 A66. arXiv:2311.12577. Bibcode:2024A&A...682A..66B. doi:10.1051/0004-6361/202348180.
- ^ "LTT 3780". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-03-06.
- ^ Cabot, Samuel H. C.; et al. (2024-05-01). "High-resolution Spectroscopic Reconnaissance of a Temperate Sub-Neptune". The Astrophysical Journal Letters. 966 (1) L10. arXiv:2403.18891. Bibcode:2024ApJ...966L..10C. doi:10.3847/2041-8213/ad3828.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
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