WASP-44

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WASP-44
Observation data
Epoch J2000       Equinox J2000
Constellation Cetus
Right ascension 00h 15m 36.7695s [1]
Declination −11° 56′ 17.286″ [1]
Apparent magnitude  (V)12.9 [2]
Characteristics
Spectral type G8V [2]
Astrometry
Proper motion (μ)RA: 15.281±0.079 [1]   mas/yr
Dec.: −30.047±0.044 [1]   mas/yr
Parallax (π)2.7151 ± 0.0416  mas [1]
Distance 1,200 ± 20  ly
(368 ± 6  pc)
Details
Mass 0.917 ± 0.077 [3]   M☉
Radius 0.865 ± 0.025 [3]   R☉
Surface gravity (log g)4.481 ± 0.034 [4]   cgs
Temperature 5410 ± 150 [2]   K
Metallicity 0.06 ± 0.1 [2]
Age 0.9 +1
−0.6 [2]   Gyr
Other designations
2MASS J00153675-1156172 [2]
Database references
SIMBAD data

WASP-44 is a G-type star 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 used 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. [4]

Contents

Observational history

WASP-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. [4] 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. [4]

The South African Astronomical Observatory, base of the WASP-South station, where WASP-44 was first observed Saao buildings in Cape Town.jpg
The South African Astronomical Observatory, base of the WASP-South station, where WASP-44 was first observed

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. [4]

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. [4]

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. [4] The paper was submitted to the Monthly Notices of the Royal Astronomical Society on May 16, 2011. [4]

Characteristics

WASP-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. [2] WASP-44's chromosphere (outermost layer) is not active. The star also does not rotate at a high velocity. [4]

The star has an apparent magnitude of 12.9. It cannot be seen from Earth with the naked eye. [2]

Planetary system

There is one known planet in the orbit of WASP-44: WASP-44b. The planet is a Hot Jupiter [4] with a mass of 0.889 Jupiters. 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. [2] 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. [2] WASPA-44b's orbital eccentricity is fit to 0.036, indicating a mostly circular orbit. [4] An analysis of transit timing variations to search for additional planets was negative. [5]

The WASP-44 planetary system [2] [5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 0.889  MJ 0.034732.423807±0.0000030.036 [4] ——

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References

  1. 1 2 3 4 5 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 Data Release 2 Vizier catalog entry
  2. 1 2 3 4 5 6 7 8 9 10 11 Schneider, J. (2011). "Notes for star WASP-44". Extrasolar Planets Encyclopaedia . Retrieved 2011-05-30.
  3. 1 2 Mancini, D. R.; et al. (2013). "Physical properties of the WASP-44 planetary system from simultaneous multi-colour photometry". Monthly Notices of the Royal Astronomical Society. 430 (4): 2932–2942. arXiv: 1301.3005 . Bibcode:2013MNRAS.430.2932M. doi:10.1093/mnras/stt095. S2CID   55450633.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 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.
  5. 1 2 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.

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