HD 42936, also known as DMPP-3, is a star located in the southern circumpolar constellation Mensa. With an apparent magnitude of 9.1,[2] it is too faint to be detected with the naked eye but can be seen with a telescope. The star is relatively close at a distance of about 153 light-years (47 parsecs) but is receding with a heliocentric radial velocity of 35.6 km/s.[1]
 Location of HD 42936 in the night sky. The star is marked within the red diamond. | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Mensa |
| Right ascension | 06h 06m 29.84725s[1] |
| Declination | −72° 30′ 45.5674″[1] |
| Apparent magnitude (V) | 9.10[2] |
| Characteristics | |
| HD 42936A | |
| Evolutionary stage | main sequence star |
| Spectral type | K0 IV/V[3] |
| B−V color index | +0.91[4] |
| HD 42936B | |
| Evolutionary stage | main sequence star |
| Spectral type | L[5] |
| Astrometry | |
| Radial velocity (Rv) | 35.64±0.49[1] km/s |
| Proper motion (μ) | RA: −0.716 mas/yr[1] Dec.: −382.755 mas/yr[1] |
| Parallax (π) | 21.2496 ± 0.1143 mas[1] |
| Distance | 153.5 ± 0.8 ly (47.1 ± 0.3 pc) |
| Absolute magnitude (MV) | 5.78[2] |
| Orbit[6] | |
| Primary | HD 42936A |
| Companion | HD 42936B |
| Period (P) | 506.89±0.01 d |
| Semi-major axis (a) | 1.139±0.004 AU |
| Eccentricity (e) | 0.596±0.001 |
| Inclination (i) | 63.89±0.78° |
| Argument of periastron (ω) (secondary) | 158.88+0.03 −0.01° |
| Semi-amplitude (K1) (primary) | 2.65731+0.00033 −0.00002 km/s |
| Details[6] | |
| HD 42936A | |
| Mass | 0.900±0.009 M☉ |
| Radius | 0.861±0.005 R☉ |
| Luminosity | 0.510±0.003[7] L☉ |
| Surface gravity (log g) | 4.266±0.045 cgs |
| Temperature | 5,201±20 K |
| Metallicity [Fe/H] | 0.147±0.013 dex |
| Rotation | 21.8+0.5 −16.5 d[8] |
| Rotational velocity (v sin i) | 3.17±0.1 km/s |
| Age | 9.6±0.8 Gyr |
| HD 42936B | |
| Mass | 91.90±0.85 MJup |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 42936 is an early K-type star with the blended luminosity class of a main sequence star and a subgiant.[3] At present it has 87% the mass of the Sun and 91% the radius of the Sun.[8] The object shines at 51% the luminosity of the Sun[7] from its photosphere at an effective temperature of 5,138 K,[8] which gives it an orangish yellow glow. HD 42936 has iron abundance 151% that of the Sun, meaning it is metal enriched[10] despite an age of 10.9 billion years.[8]
HD 42936 has a very low mass companion star in a close orbit,[8] approaching to 0.498 AU at periastron.[6]
Planetary system
editIn 2019, a radial velocity analysis carried out by a team of astronomers led by astronomer John R. Barnes of the Dispersed Matter Planet Project (DMPP) confirmed the existence of a super-Earth in orbit around DMPP-3 A. Planets in close binary star systems such as this are rare.[8]
A follow-up study in 2023 refined the parameters of the planet and companion star, and detected two additional radial velocity signals. One of these could be caused by a second, Earth-mass planet closer to the star, but the other, 800-day signal cannot be caused by an orbiting body because the companion star would make its orbit unstable. The study concludes that the 800-day signal must be caused by stellar activity, but if not for the companion star it could have been considered a likely planet, which has implications for other radial velocity planet detections.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c (unconfirmed) | ≥1.065+0.173 −0.259 M🜨 |
0.033+0.002 −0.0001 |
2.26+0.20 −0.10 |
0 | — | — |
| b | ≥2.22+0.50 −0.28 M🜨 |
0.0670+0.0003 −0.0002 |
6.6732+0.0011 −0.0003[8] |
0.174+0.032 −0.084 |
— | — |
See also
editReferences
edit- ^ a b c d e f 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 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 255204555.
- ^ a b Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0. Bibcode:1975mcts.book.....H.
- ^ Cousins, A. W. J.; Stoy, R. H. (1962). "Photoelectric magnitudes and colours of Southern stars". Royal Greenwich Observatory Bulletins. 64: 103. Bibcode:1962RGOB...64..103C.
- ^ Haswell, Carole A.; Staab, Daniel; Barnes, John R.; Anglada-Escudé, Guillem; Fossati, Luca; Jenkins, James S.; Norton, Andrew J.; Doherty, James P. J.; Cooper, Joseph (2019). "Dispersed Matter Planet Project discoveries of ablating planets orbiting nearby bright stars". Nature Astronomy. 4 (4): 408–418. arXiv:1912.10874. doi:10.1038/s41550-019-0973-y. S2CID 209444484.
- ^ a b c d e Stevenson, Adam T.; Haswell, Carole A.; et al. (May 2023). "DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections". Monthly Notices of the Royal Astronomical Society. arXiv:2305.06263.
- ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d e f g Barnes, John R.; Haswell, Carole A.; Staab, Daniel; Anglada-Escudé, Guillem; Fossati, Luca; Doherty, James P. J.; Cooper, Joseph; Jenkins, James S.; Díaz, Matías R.; Soto, Maritza G.; Peña Rojas, Pablo A. (2019). "An ablating 2.6-M🜨 planet in an eccentric binary from the Dispersed Matter Planet Project". Nature Astronomy. 4 (4): 419–426. arXiv:1912.10793. doi:10.1038/s41550-019-0972-z. S2CID 209444780.
- ^ HD 42936, entry, SIMBAD. Accessed online December 24, 2019.
- ^ Jenkins, J. S.; Jones, H. R. A.; Pavlenko, Y.; Pinfield, D. J.; Barnes, J. R.; Lyubchik, Y. (July 2008). "Metallicities and activities of southern stars". Astronomy & Astrophysics. 485 (2): 571–584. arXiv:0804.1128. Bibcode:2008A&A...485..571J. doi:10.1051/0004-6361:20078611. ISSN 0004-6361.