WASP-44 is a G-type star about 1,180 light-years (360 parsecs) away in the constellation Cetus that is orbited by the Jupiter-size planet WASP-44b. The star is slightly less massive and slightly smaller than the Sun; it is also slightly cooler, but is more metal-rich. The star was observed by SuperWASP, an organization searching for exoplanets, starting in 2009; manual follow-up observations using WASP-44's spectrum and measurements of its radial velocity led to the discovery of the transiting planet WASP-44b. The planet and its star were presented along with WASP-45b and WASP-46b on May 17, 2011 by a team of scientists testing the idea that hot Jupiters tend to have circular orbits, an assumption that is made when the orbital eccentricity of such planets are not well-constrained.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 00h 15m 36.76947s[1] |
| Declination | −11° 56′ 17.2848″[1] |
| Apparent magnitude (V) | 13.05[2] |
| Characteristics | |
| Spectral type | G8V[3] |
| Astrometry | |
| Radial velocity (Rv) | −3.10±1.32[1] km/s |
| Proper motion (μ) | RA: 15.272(22) mas/yr[1] Dec.: −30.159(14) mas/yr[1] |
| Parallax (π) | 2.7644 ± 0.0199 mas[1] |
| Distance | 1,180 ± 8 ly (362 ± 3 pc) |
| Details[4] | |
| Mass | 0.929+0.053 −0.050 M☉ |
| Radius | 0.923+0.021 −0.020 R☉ |
| Luminosity | 0.680+0.031 −0.029 L☉ |
| Surface gravity (log g) | 4.476±0.030 cgs |
| Temperature | 5457±46 K |
| Metallicity [Fe/H] | 0.099+0.092 −0.089 dex |
| Rotational velocity (v sin i) | 3.20±0.90[5] km/s |
| Age | 6.0+4.3 −3.8 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Observational history
editWASP-44 was observed between July and November 2009 by WASP-South, a station of the SuperWASP planet-searching program based at the South African Astronomical Observatory. Observations of the star revealed a periodic decrease in its brightness. WASP-South, along with the SuperWASP-North station at the Roque de los Muchachos Observatory on the Canary Islands, collected 15,755 photometric observations, allowing scientists to produce a more accurate light curve.[3] Another set of observations yielded a 6,000 point photometric data set, but the light curve was prepared late and was not considered in the discovery paper.[3]
In 2010, a European science team investigated the star using the CORALIE spectrograph and collected seventeen spectra of WASP-44. From the spectra, radial velocity measurements were extrapolated. Analysis of collected CORALIE data ruled out the possibility that the detected radial velocity was caused by the blended spectrum of a spectroscopic binary star, supporting the possibility that the body orbiting WASP-44 was indeed a planet, designated WASP-44b.[3]
The Leonhard Euler Telescope at La Silla Observatory in Chile was used to follow up on the planet circling WASP-44, searching for a point at which the planet transited, or crossed in front of, its host star. One transit was detected.[3]
WASP-44, its recently discovered planet, the planets orbiting WASP-45 and WASP-46, and a discussion exploring the validity of the common assumption amongst scientists that closely orbiting hot Jupiter planets have highly circular orbits unless proven otherwise, were reported in a single discovery paper that was published on May 17, 2011 by the Royal Astronomical Society.[3] The paper was submitted to the Monthly Notices of the Royal Astronomical Society on May 16, 2011.[3]
Characteristics
editWASP-44 is a G-type star (the same class of star as the Sun) that is located in the Cetus constellation. WASP-44 has a mass that is 0.951 times that of the Sun. In terms of size, WASP-44 has a radius that is 0.927 times that of the Sun. WASP-44 has an effective temperature of 5410 K (cooler than the Sun). However, the star is metal-rich with relation to the Sun. Its measured metallicity is [Fe/H] = 0.06, or 1.148 times that the amount of iron found in the Sun.[6] WASP-44's chromosphere (outermost layer) is not active. The star also does not rotate at a high velocity.[3]
The star has an apparent magnitude of 12.9. It cannot be seen from Earth with the naked eye.[6]
Planetary system
editThere is one known planet in the orbit of WASP-44: WASP-44b. The planet is a hot Jupiter[3] with a mass of 0.889 times that of Jupiter. Its radius is 1.14 times that of Jupiter. WASP-44b orbits its host star every 2.4238039 days at a distance of 0.03473 AU, approximately 3.47% the mean distance between the Earth and Sun.[6] With an orbital inclination of 86.02º, WASP-44b has an orbit that exists almost edge-on to its host star with respect to Earth.[6] WASP-44b's orbital eccentricity is fit to 0.036, indicating a mostly circular orbit.[3] An analysis of transit timing variations to search for additional planets was negative.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.860+0.072 −0.068 MJ |
0.03474+0.00040 −0.00043[5] |
2.4238133(23)[5] | 0.039+0.047 −0.028 |
85.98+0.39 −0.35° |
1.127+0.035 −0.034 RJ |
References
edit- ^ a b c d e 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 "WASP-44". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 December 2023.
- ^ a b c d e f g h i j k Anderson, D. R.; et al. (2012). "WASP-44b, WASP-45b and WASP-46b: three short-period, transiting extrasolar planets". Monthly Notices of the Royal Astronomical Society. 422 (3): 1988–1998. arXiv:1105.3179. Bibcode:2012MNRAS.422.1988A. doi:10.1111/j.1365-2966.2012.20635.x. S2CID 34406657.
- ^ a b Addison, Brett; Wright, Duncan J.; et al. (November 2019). "Minerva-Australis. I. Design, Commissioning, and First Photometric Results". Publications of the Astronomical Society of the Pacific. 131 (1005): 115003. arXiv:1901.11231. Bibcode:2019PASP..131k5003A. doi:10.1088/1538-3873/ab03aa.
- ^ a b c Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics. 602: A107. arXiv:1704.00373. Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882. S2CID 118923163.
- ^ a b c d Schneider, J. (2011). "Notes for star WASP-44". Extrasolar Planets Encyclopaedia. Archived from the original on June 1, 2011. Retrieved 2011-05-30.
- ^ Moyano, M.; et al. (2017). "Multi-band characterization of the hot Jupiters: WASP-5b, WASP-44b and WASP-46b". Monthly Notices of the Royal Astronomical Society. 471 (1): 650–657. arXiv:1708.05700. Bibcode:2017MNRAS.471..650M. doi:10.1093/mnras/stx1612. S2CID 119087346.