| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sextans[1] |
| Right ascension | 10h 42m 14.0837s[2] |
| Declination | −03° 50′ 06.260″[2] |
| Apparent magnitude (V) | 10.165(46)[3] |
| Characteristics | |
| Spectral type | G5[4] |
| Apparent magnitude (J) | 9.092(29)[5] |
| Apparent magnitude (H) | 8.738(55)[5] |
| Apparent magnitude (K) | 8.641(19)[5] |
| Variable type | Planetary transit[4] |
| Astrometry | |
| Radial velocity (Rv) | −8.92(6)[6] km/s |
| Proper motion (μ) | RA: 19.133(20) mas/yr[2] Dec.: 17.058(18) mas/yr[2] |
| Parallax (π) | 6.2241 ± 0.0175 mas[2] |
| Distance | 524 ± 1 ly (160.7 ± 0.5 pc) |
| Details[7] | |
| Mass | 0.949+0.022 −0.019[8] M☉ |
| Radius | 1.335+0.025 −0.029[8] R☉ |
| Surface gravity (log g) | 4.23(2) cgs |
| Temperature | 5842(14) K |
| Metallicity [Fe/H] | −0.19(1) dex |
| Rotational velocity (v sin i) | 0.53+0.07 −0.05 km/s |
| Age | 9.656(1.002) Gyr |
| Other designations | |
WASP-127 is an old G5 type star. There is so far one planet detected, a low density sub-Saturn type.[4]
Stellar system
editWASP-127 is a G5-type star, less massive but with a radius about 30% larger than the Sun's. It is nearing the end of its main sequence phase at 9.7 billion years old and is transitioning into its subgiant phase. The star is photometrically stable, and slowly rotating.[7]
Planetary system
editCurrently, one planet is known to orbit WASP-127, which is described as either a super-Neptune or a sub-Saturn planet with a mass 16% that of Jupiter and a heavily inflated radius 1.3 times that of Jupiter. This results in it being one of the least dense planets known. It orbits its star in just over 4 days.[8][6]
WASP-127b
editDiscovery
editWASP-127b, along with WASP-136b and WASP-138b, was discovered by the Wide Angle Search for Planets. The host star, WASP-127, was monitored from 2006 to 2014, accumulating 87,349 photometric data points. Analysis of this data resulted in the discovery of the transits of WASP-127b across the face of its parent star. Follow-up photometry from various telescopes was utilized to refine the system parameters. Radial velocity measurements, conducted by the CORALIE spectrograph and the SOPHIE échelle spectrograph, served to confirm the planet's presence and ascertain its mass.[4]
Orbit
editA study of the secondary Eclipse, when the planet passes behind its host star, by the Spitzer Space Telescope found that the best-fit eclipse phases for WASP-127b are consistent with the expectation for a circular orbit.[10]
Observations of the Rossiter-McLaughlin effect during a transit using the ESPRESSO spectrograph at the European Southern Observatory's Very Large Telescope indicate that WASP-127b, unlike the planets in our Solar System, orbits in the opposite direction to its star and on a different plane than the equatorial one. This is an unusual alignment for a hot Saturn within an ancient stellar system and may suggest the presence of an unseen companion.[7][11][12]
Atmosphere
editThe first indication of a feature-rich transmission spectrum on this planet was obtained at low resolution with the Andalucia Faint Object Spectrograph and Camera (ALFOSC) mounted on the 2.5m Nordic Optical Telescope at Roque de los Muchachos Observatory.[13] These findings were later confirmed with higher precision using the OSIRIS instrument at the 10m GranTeCan, showing not only sodium and potassium absorption but also a tentative detection of lithium in the planet.[14] However, follow-up studies of the planet at high resolution in the optical wavelength range only measured a weak signal for sodium with ESPRESSO at the 8m-VLT[7] and HARPS[8], the latter being compatible with a non-detection. The atmosphere were further constrained by successful eclipse measurements with Spitzer, which determined the planet's dayside temperature as approximately 1400 Kelvin.[10] Low-resolution space based spectroscopy obtained with the Wide Field Camera 3 on the Hubble Space telescope led to a detection of water in the planet's transmission spectrum.[15][16] An atmospheric retrieval study combining the Hubble and Spitzer transit data led to conflicting carbon-to-oxygen ratios (C/O) depending on whether chemical equilibrium or free chemistry assumptions were adopted (leading to values of C/O 0.8 and C/O ∼ 0.0 respectively).[16] This degeneracy was seemingly solved through recent high-resolution observations of this target over a large wavelength range in the near-infrared (∼ 980 - 2500 nm) using the SPIRou spectrograph, which yielded a detection of water (H2O) and hydroxyl (OH) but no carbon monoxide (CO). The non-detection of CO led to strong upper limits on the CO abundance (log10(CO) < −4.0) and favored a disequilibrium case with a low C/O ratio for this planet in the joint retrieval of SPIRou + HST + Spitzer data.[6] The H2O and OH signals found in this high-resolution study were detected to be strongly blue-shifted (by approximately 10 km s−1) from the planet’s rest frame and the authors discussed the possibly of this signal being only part of a broadened velocity signature, with other parts of the signal hidden within the noise.[6]
During the transit event of WASP-127b on the night of 24-25 March 2022, the upgraded infrared spectrograph CRIRES+ on the 8m UT3 telescope at the Very Large Telescope Facility of the European Southern Observatory was utilized. The transmission spectrum obtained revealed strong water and carbon monoxide signals with two distinct cross-correlation peaks. This dual-peaked signal suggests a supersonic equatorial jet and weaker signals at the poles, with the peaks corresponding to the planet's morning and evening terminators. An equatorial jet velocity of 7.7 km/s was deduced from the overall equatorial velocity of 9.3 km/s and the planet's tidally locked rotation, leading to the identification of different atmospheric properties for both terminators and the polar regions. The evening terminator appears hotter than the morning by 175 K, and the subdued polar signals could be due to much lower temperatures or a high cloud cover. The analysis resulted in a solar C/O ratio and metallicity determination.[17]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.1647+0.0214 −0.0172 MJ |
0.04840+0.00136 −0.00095 |
4.17806473(25)[18] | 0.0 (fixed)[10] | 87.84+0.36 −0.33° |
1.311+0.025 −0.029 RJ |
References
edit- ^ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
- ^ 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.
- ^ Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H. Vizier catalog entry
- ^ a b c d Lam, K. W. F.; et al. (2017). "From dense hot Jupiter to low-density Neptune: The discovery of WASP-127b, WASP-136b, and WASP-138b". Astronomy & Astrophysics. 599 A3. arXiv:1607.07859. Bibcode:2017A&A...599A...3L. doi:10.1051/0004-6361/201629403.
- ^ a b c Skrutskie, M. F.; et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. Vizier catalog entry
- ^ a b c d Boucher, Anne; et al. (2023-04-26). "CO or no CO? Narrowing the CO abundance constraint and recovering the H2O detection in the atmosphere of WASP-127 b using SPIRou". Monthly Notices of the Royal Astronomical Society. 522 (4). Oxford University Press (OUP): 5062–5083. arXiv:2303.03232. Bibcode:2023MNRAS.522.5062B. doi:10.1093/mnras/stad1247.
- ^ a b c d Allart, R.; et al. (2020). "WASP-127b: a misaligned planet with a partly cloudy atmosphere and tenuous sodium signature seen by ESPRESSO". Astronomy & Astrophysics. 644 A155. arXiv:2010.15143. Bibcode:2020A&A...644A.155A. doi:10.1051/0004-6361/202039234.
- ^ a b c d e Seidel, J. V.; et al. (2020). "Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS): VI. Non-detection of sodium with HARPS on the bloated super-Neptune WASP-127b". Astronomy & Astrophysics. 643 A45. arXiv:2009.13386. Bibcode:2020A&A...643A..45S. doi:10.1051/0004-6361/202039058.
- ^ "Wasp-127". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-04-19.
- ^ a b c Wallack, Nicole L.; et al. (2021-07-01). "Trends in Spitzer Secondary Eclipses". The Astronomical Journal. 162 (1) 36. arXiv:2103.15833. Bibcode:2021AJ....162...36W. doi:10.3847/1538-3881/abdbb2.
- ^ Cristo, E.; et al. (2022). "CaRM: Exploring the chromatic Rossiter-McLaughlin effect: The cases of HD 189733b and WASP-127b". Astronomy & Astrophysics. 660 A52. arXiv:2201.06531. Bibcode:2022A&A...660A..52C. doi:10.1051/0004-6361/202142353.
- ^ "Cloud-spotting on a distant exoplanet" (Press release). Europlanet Society. 2021-09-23. Retrieved 2024-05-25.
- ^ Palle, E.; et al. (2017). "Feature-rich transmission spectrum for WASP-127b: Cloud-free skies for the puffiest known super-Neptune?". Astronomy & Astrophysics. 602 L15. arXiv:1705.09230. Bibcode:2017A&A...602L..15P. doi:10.1051/0004-6361/201731018.
- ^ Chen, G.; et al. (2018). "The GTC exoplanet transit spectroscopy survey: IX. Detection of haze, Na, K, and Li in the super-Neptune WASP-127b". Astronomy & Astrophysics. 616 A145. arXiv:1805.11744. Bibcode:2018A&A...616A.145C. doi:10.1051/0004-6361/201833033.
- ^ Skaf, Nour; et al. (2020-09-01). "ARES. II. Characterizing the Hot Jupiters WASP-127 b, WASP-79 b, and WASP-62b with the Hubble Space Telescope". The Astronomical Journal. 160 (3) 109. arXiv:2005.09615. Bibcode:2020AJ....160..109S. doi:10.3847/1538-3881/ab94a3.
- ^ a b Spake, Jessica J; et al. (January 2021). "Abundance measurements of H2O and carbon-bearing species in the atmosphere of WASP-127b confirm its supersolar metallicity". Monthly Notices of the Royal Astronomical Society. 500 (3): 4042–4064. arXiv:1911.08859. Bibcode:2021MNRAS.500.4042S. doi:10.1093/mnras/staa3116.
- ^ Nortmann, L.; et al. (2024). "CRIRES+ transmission spectroscopy of WASP-127b. Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet". arXiv:2404.12363.
- ^ Wang, Wenqin; et al. (2024-01-01). "Long-term Variations in the Orbital Period of Hot Jupiters from Transit-timing Analysis Using TESS Survey Data". The Astrophysical Journal Supplement Series. 270 (1) 14. Table 2. arXiv:2310.17225. Bibcode:2024ApJS..270...14W. doi:10.3847/1538-4365/ad0847.
