TOI-1338
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pictor[1] |
| Right ascension | 06h 08m 31.968s[2] |
| Declination | −59° 32′ 28.08″[2] |
| Apparent magnitude (V) | 11.72[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | F8V + M[5] |
| Variable type | eclipsing[5] |
| Astrometry | |
| Radial velocity (Rv) | 23.56±5.34[2] km/s |
| Proper motion (μ) | RA: −12.057[2] mas/yr Dec.: +34.513[2] mas/yr |
| Parallax (π) | 2.4752±0.0099 mas[2] |
| Distance | 1,318 ± 5 ly (404 ± 2 pc) |
| Orbit[6] | |
| Period (P) | 14.6085659+0.0000062 −0.0000057 d |
| Semi-major axis (a) | 0.1321+0.0024 −0.0025 AU[3] |
| Eccentricity (e) | 0.155489+0.000011 −0.000010 |
| Inclination (i) | 90.403+0.045 −0.047° |
| Argument of periastron (ω) (secondary) | 117.7638+0.0042 −0.0041° |
| Semi-amplitude (K1) (primary) | 21.619±0.007[3] km/s |
| Details | |
| TOI-1338 A | |
| Mass | 1.0936±0.0072[6] M☉ |
| Radius | 1.313±0.0038[6] R☉ |
| Luminosity | 2.089±0.098[4] L☉ |
| Surface gravity (log g) | 4.0±0.08[3] cgs |
| Temperature | 6,031±46[4] K |
| Metallicity [Fe/H] | +0.01±0.05[3] dex |
| Rotation | 19±3 d[3] |
| Rotational velocity (v sin i) | 3.6±0.6[3] km/s |
| Age | 6.0±0.3[4] Gyr |
| TOI-1338 B | |
| Mass | 0.3069±0.0012[6] M☉ |
| Radius | 0.30582±0.00094[6] R☉ |
| Luminosity | 0.0091±0.0016[4] L☉ |
| Temperature | 3,220±135[4] K |
| Other designations | |
| TOI-1338, TIC 260128333, TYC 8533-950-1, 2MASS J06083197-5932280, BEBOP-1, EBLM J0608-59, RAVE J060832.0-593228[7] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
TOI-1338 (also known as BEBOP-1 or EBLM J0608-59) is an eclipsing binary star system located in the constellation Pictor, about 1,300 light-years (400 pc) from Earth. The binary system consists of a large, yellow-white F-type main-sequence star, and a smaller, red dwarf (M-type) star.[4][8] Viewed from Earth, TOI-1338 appears at an apparent magnitude of 11.7, which is too faint to be seen with the naked eye.[8] It is known for hosting two circumbinary exoplanets: TOI-1338 b, a Saturn-sized super-puff planet, and TOI-1338 c, a Saturn-mass gas giant.
Location and brightness
[edit]TOI-1338 is located in the constellation Pictor, about 59 and a half degrees south of the celestial equator.[8] When viewed from Earth in visible light, it appears as a single star[a] with an apparent magnitude of 11.7—too faint to be seen with the naked eye or a small telescope.[8] According to the latest parallax measurements by the Gaia satellite (as of 2020[update]), the distance of TOI-1338 from Earth 1,318 ± 5 light-years (404 ± 2 parsecs).[7][8][b] The NASA Exoplanet Archive gives a slightly smaller distance of 1,302 ± 10 ly (399 ± 3 pc).[9] The star system does not appear reddened (very low extinction of E(B–V)=0.0036±0.0018), which implies there is very little interstellar dust between it and Earth.[4]: 4579
As of 2026[update], TOI-1338 is the brightest star system known to have at least one transiting circumbinary planet.[10] For this reason, astronomers consider TOI-1338 a favorable target for observing its planet's transits via transmission spectroscopy, which would enable the determination of the planet's atmospheric composition.[10][11]: 705 [6]: 11
Observational history
[edit]TOI-1338 was first catalogued by the Hipparcos satellite during the 1990s, and published in the Tycho-2 (TYC) Catalogue in 2000.[7] The star was found to be periodically eclipsing when it was observed by the Wide Angle Search for Planets (WASP) during the 2000s. However, the star's eclipses were initially mistaken for transits by a hot Jupiter exoplanet.[3]: 2 [4]: 4577 Upon further examination by the Eclipsing Binary, Low Mass (EBLM) project in 2009, the star became recognized as an eclipsing binary system and was given the designation EBLM J0608-59.[3]: 2 [11]: 705
Under the EBLM project, the star system received extensive observations from telescopes in Chile during 2009–2022, with the goal of characterizing the physical properties of its two stars.[12]: 2573 During that time, two other independent projects had begun observing the star system: the Binaries Escorted By Orbiting Planets (BEBOP) project in 2014,[3]: 7 [11]: 705 and the Transiting Exoplanet Survey Satellite (TESS) in 2018.[c] The star system became known as TOI-1338 ("TOI" standing for "TESS Object of Interest") in 2020, when astronomers announced the discovery of the first exoplanet orbiting it.[3][14] The other designation, BEBOP-1, was given to the star system in 2023, when astronomers of the BEBOP project announced the discovery of a second planet orbiting it.[11][15]
The James Webb Space Telescope (JWST) is scheduled to observe TOI-1338 on 24 and 25 September 2026, when the inner planet of TOI-1338 is predicted to transit both stars.[d] JWST will observe the transit using transmission spectroscopy, which could determine the composition of the planet's atmosphere. If successful, these observations will provide the first characterization of a circumbinary exoplanet's atmosphere.[10]
-
Location of TOI-1338 (yellow circle) in the constellation Pictor -
![A light curve for TOI-1338, plotted from TESS satellite data.[17] The inset plots show the primary and secondary eclipses on an expanded scale.](//upload.wikimedia.org/wikipedia/commons/thumb/b/bd/TOI-1338LightCurve.png/500px-TOI-1338LightCurve.png)
A light curve for TOI-1338, plotted from TESS satellite data.[17] The inset plots show the primary and secondary eclipses on an expanded scale.
![A light curve for TOI-1338, plotted from TESS satellite data.[17] The inset plots show the primary and secondary eclipses on an expanded scale.](/proxy/https://en.wikipedia.org/wiki/File:TOI-1338LightCurve.png)
Binary system
[edit]Physical characteristics
[edit]TOI-1338 is a single-lined spectroscopic binary system, consisting of an F8 star and a red dwarf of spectral type M. The red dwarf is about nine magnitudes fainter than the primary star and cannot be detected in the spectrum.[18][3]
The primary star of the binary system, A, is hotter (temperature 6031 K), brighter (luminosity 2.1 L☉), larger (radius 1.32 R☉, and more massive (1.1 M☉) than the Sun.[4]: 4581 The secondary, B, is cooler (temperature 3300 K), dimmer (luminosity 0.009 L☉),smaller (radius 0.31 R☉, and less massive (0.31 M☉) than the Sun.[8][4]: 4581 The system has an age of six billion years.[4]
Orbit
[edit]The two stars orbit each other every 14.6 days and are mutually separated by an average distance of about 0.13 astronomical units (20 million km or 12 million mi).[11]: 704 The orbit of the two stars is inclined at 89.7° to the plane of the sky (so edge-on) and both primary and secondary eclipses can be observed, although the brightness changes are very small. The primary eclipse occurs when the hotter primary star is partially occulted by the cooler secondary. It lasts about five hours and the brightness decreases by about 4%. The secondary eclipses occur when the cooler star is occulted by the hotter star. They also last about five hours but the brightness drops by less than half a percent.[3]
Planetary system
[edit]
The planet TOI-1338 b is between Neptune and Saturn in size, and has an orbit that is within ~1° coplanar with the binary.[3] Its mass is estimated to be roughly 11 times that of Earth, indicating a low density similar to that of circumbinary planet Kepler-47c.[6]
The spin of the primary star aligns with the orbits of the binary and the planet (spin-orbit angle β = 2.8°±17.1°). This is the second time the Rossiter–McLaughlin effect was measured for a star hosting a circumbinary planet. Kepler-16 was the first system with such a measurement. The measurement of the alignment for TOI-1338 suggests that the planet formed from a single circumbinary disk.[19]
TOI-1338 c, or BEBOP-1c,[11] is a gas giant about 75 times the mass of Earth. It is also coplanar (or nearly so) with the binary stars and planet b.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 11.3±2.1 M🜨 | 0.4607+0.0084 −0.0088[3] |
95.4001+0.0062 −0.0056 |
0.0331+0.0022 −0.0021 |
90.494+0.013 −0.014 |
7.661±0.053 R🜨 |
| c | 75.4+4.0 −3.6 M🜨 |
0.794±0.016[11] | 215.79+0.46 −0.51 |
0.037+0.032 −0.026 |
97.0+6.7 −6.8 |
— |
See also
[edit]- Circumbinary planet
- Kepler-16 – eclipsing binary star with the first discovered circumbinary exoplanet
- Kepler-47 – an eclipsing binary star system with multiple circumbinary gas giant planets
- Kepler-64 – a quadruple star system with a circumbinary gas giant
Notes
[edit]- ^ The two stars orbit too close to each other to be resolved individually in images. See Figure 6 in Kostov et al. (2020).[3]
- ^ Gaia's Early Data Release 3 (EDR3) gives a parallax of 2.4752±0.0099 milliarcseconds for TOI-1338.[7] Parallax can be converted into distance via the formula: , where is the star's distance in parsecs and is the star's parallax in arcseconds.[4]: 4579
- ^ TOI-1338 was observed by TESS while it was observing its first twelve sectors (areas) of the sky.[3] TESS began observing its first sector in July 2018.[13]
- ^ The description for JWST's TOI-1338 observing program mentions that TOI-1338 b will transit its larger parent star between the dates BJD 2461307.704 and 2461308.577 (2026 September 24 04:54 UT to 25 01:50 UT).[10][16] TOI-1338 b will also transit its smaller parent star between BJD 2461308.583 and 2461308.856 (2026 September 25 02:00 UT to 08:33 UT).[10][16]
References
[edit]- ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- ^ 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 d e f g h i j k l m n o p q Kostov, Veselin B.; Orosz, Jerome A.; Feinstein, Adina D.; Welsh, William F.; Cukier, Wolf; Haghighipour, Nader; et al. (7 May 2020). "TOI-1338: TESS' First Transiting Circumbinary Planet". The Astronomical Journal. 159 (6): 253. arXiv:2004.07783. Bibcode:2020AJ....159..253K. doi:10.3847/1538-3881/ab8a48. ISSN 1538-3881.
- ^ a b c d e f g h i j k l m Maxted, P. F. L.; Miller, N. J.; Sebastian, D.; Triaud, A. H. M. J.; Martin, D. V.; Duck, A.; et al. (July 2024). "Fundamental effective temperature measurements for eclipsing binary stars – V. The circumbinary planet system EBLM J0608−59". Monthly Notices of the Royal Astronomical Society. 531 (4): 4577–4583. arXiv:2406.04204. Bibcode:2024MNRAS.531.4577M. doi:10.1093/mnras/stae1434.
- ^ a b Triaud, Amaury H. M. J.; Martin, David V.; Ségransan, Damien; Smalley, Barry; Maxted, Pierre F. L.; Anderson, David R.; Bouchy, François; Collier Cameron, Andrew; Faedi, Francesca; Gómez Maqueo Chew, Yilen; Hebb, Leslie; Hellier, Coel; Marmier, Maxime; Pepe, Francesco; Pollacco, Don; Queloz, Didier; Udry, Stéphane; West, Richard (2017). "The EBLM Project. IV. Spectroscopic orbits of over 100 eclipsing M dwarfs masquerading as transiting hot Jupiters". Astronomy and Astrophysics. 608: A129. arXiv:1707.07521. Bibcode:2017A&A...608A.129T. doi:10.1051/0004-6361/201730993. S2CID 119372451.
- ^ a b c d e f g h i Wang, Mu-Tian; Liu, Hui-Gen (July 2024). "Photo-dynamical Analysis of Circumbinary Multi-planet System TOI-1338: A Fully Coplanar Configuration with a Puffy Planet". The Astronomical Journal. 168 (1): 31. arXiv:2404.18415. Bibcode:2024AJ....168...31W. doi:10.3847/1538-3881/ad4a60.
- ^ a b c d "TOI-1338". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 12 August 2024.
- ^ a b c d e f "Star TOI 1338". stellarcatalog.com. Retrieved 11 May 2026.
- ^ "TOI-1338 Overview". NASA Exoplanet Archive. Caltech IPAC. Retrieved 11 May 2026.
- ^ a b c d e French, Jenni; et al. (4 May 2026). "JWST Proposal 11302 - Sunsets on Tatooine: Characterising the First Circumbinary Planet Atmosphere". Cycle 5 General Observer (GO) program. Space Telescope Science Institute. Retrieved 10 May 2026.
- ^ a b c d e f g Standing, Matthew R.; Sairam, Lalitha; Martin, David V.; Triaud, Amaury H. M. J.; Correia, Alexandre C. M.; Coleman, Gavin A. L.; Baycroft, Thomas A.; Kunovac, Vedad; Boisse, Isabelle; Andrew Collier Cameron; Dransfield, Georgina; Faria, João P.; Gillon, Michaël; Hara, Nathan C.; Hellier, Coel; Howard, Jonathan; Lane, Ellie; Mardling, Rosemary; Maxted, Pierre F. L.; Miller, Nicola J.; Nelson, Richard P.; Orosz, Jerome A.; Pepe, Franscesco; Santerne, Alexandre; Sebastian, Daniel; Udry, Stéphane; Welsh, William F. (2023). "Radial-velocity discovery of a second planet in the TOI-1338/BEBOP-1 circumbinary system". Nature Astronomy. 7 (6): 702–714. arXiv:2301.10794. Bibcode:2023NatAs...7..702S. doi:10.1038/s41550-023-01948-4. S2CID 259138442.
- ^ Sebastian, D.; Triaud, A. H. M. J.; Brogi, M.; Baycroft, Thomas A.; Standing, Matthew R.; Maxted, Pierre F. L.; et al. (May 2024). "The EBLM project - XIII. The absolute dynamical masses of the circumbinary planet host TOI-1338/BEBOP-1, and applications to the study of exoplanet atmospheres". Monthly Notices of the Royal Astronomical Society. 530 (3): 2572–2589. arXiv:2402.06449. Bibcode:2024MNRAS.530.2572S. doi:10.1093/mnras/stae459.
- ^ "Observation Sector 1". tess.mit.edu. Massachusetts Institute of Technology. Retrieved 7 May 2026.
- ^ Kazmierczak, Jeanette (7 January 2020). "NASA's TESS Mission Uncovers Its 1st World With Two Stars". NASA. Retrieved 6 February 2026.
- ^ "A new Tatooine-like multi-planetary system identified". University of Birmingham. 12 June 2023. Archived from the original on 14 July 2023. Retrieved 11 May 2026.
- ^ a b "JD Date/Time Converter". JPL Solar System Dynamics. NASA. Retrieved 10 May 2026.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ Martin, David V.; Triaud, Amaury H. M. J.; Udry, Stephane; Marmier, Maxime; Maxted, Pierre F. L.; Cameron, Andrew Collier; Hellier, Coel; Pepe, Francesco; Pollacco, Don; Segransan, Damien; West, Richard (April 2019). "The BEBOP radial-velocity survey for circumbinary planets I. Eight years of CORALIE observations of 47 single-line eclipsing binaries and abundance constraints on the masses of circumbinary planets". Astronomy & Astrophysics. 624: A68. arXiv:1901.01627. Bibcode:2019A&A...624A..68M. doi:10.1051/0004-6361/201833669. ISSN 0004-6361.
- ^ Kunovac Hodzic, Vedad; Triaud, Amaury H. M. J.; Martin, David V.; Fabrycky, Daniel C.; Cegla, Heather M.; Collier Cameron, Andrew; Gill, Samuel; Hellier, Coel; Kostov, Veselin B.; Maxted, Pierre F. L.; Orosz, Jerome A. (1 July 2020). "The EBLM project - VII. Spin-orbit alignment for the circumbinary planet host EBLM J0608-59 A/TOI-1338 A". Monthly Notices of the Royal Astronomical Society. 497 (2): 1627–1633. arXiv:2007.05514. Bibcode:2020MNRAS.497.1627K. doi:10.1093/mnras/staa2071. S2CID 220486377.
External links
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