DS Tucanae

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DS Tucanae
DS Tuc A(right)B(left) H+OPEN.png
DS Tucanae imaged with the NTT. DS Tucanae A is on the right and DS Tucanae B is on the left.
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Tucana
DS Tucanae A
Right ascension 23h 39m 39.48081s [1]
Declination −69° 11′ 44.7077″ [1]
Apparent magnitude  (V)8.47 [2]
DS Tucanae B
Right ascension 23h 39m 39.26965s [3]
Declination −69° 11′ 39.4936″ [3]
Apparent magnitude  (V)9.84 [4]
Characteristics
Spectral type G6V+K3V [4]
Variable type RS CVn [5]
Astrometry
A
Radial velocity (Rv)7.20 [6]  km/s
Proper motion (μ)RA: 79.529 [1]   mas/yr
Dec.: −67.551 [1]   mas/yr
Parallax (π)22.6367 ± 0.0150  mas [1]
Distance 144.08 ± 0.10  ly
(44.18 ± 0.03  pc)
B
Radial velocity (Rv)5.32 [7]  km/s
Proper motion (μ)RA: 78.133 [3]   mas/yr
Dec.: −65.845 [3]   mas/yr
Parallax (π)22.6524 ± 0.0125  mas [3]
Distance 143.98 ± 0.08  ly
(44.15 ± 0.02  pc)
Details
DS Tucanae A
Mass 1.01±0.06 [8]   M☉
Radius 0.964±0.029 [8]   R☉
Luminosity 0.725±0.013 [8]   L☉
Temperature 5,428±80 [8]   K
Rotational velocity (v sin i)27.75+1.73
−1.54 [9]  km/s
Age 45±4 [8]   Myr
DS Tucanae B
Mass 0.84±0.06 [8]   M☉
Radius 0.864±0.036 [8]   R☉
Luminosity0.327±0.010 [8]   L☉
Temperature 4,700±90 [8]   K
Age 45±4 [8]   Myr
Other designations
DS  Tuc, HD  222259, CCDM  J23397-6912AB, CD−69°2106, HIP  116748, WDS  J23397-6912AB, TIC 410214986, TOI  200
Database references
SIMBAD AB
A
B
Ab

DS Tucanae (HD 222259) is a binary star system 144 light years away in the constellation of Tucana. It has an apparent visual magnitude of 8.5, [8] and is a RS Canum Venaticorum variable. [5] The system is notable for being young as a member of the 45 Myr old Tucana-Horologium moving group [10] and for the primary star hosting the confirmed exoplanet DS Tucanae Ab, discovered by THYME, using TESS. [11] [8] [12] [13]

Contents

Stellar system

A light curve for DS Tucanae, plotted from TESS data DSTucLightCurve.png
A light curve for DS Tucanae, plotted from TESS data

DS Tucanae is a visual binary. [4] The binary consists of a G6V primary and a K3V secondary separated by 5″ . [15] Based on radial velocity measurements it was suggested that the secondary itself is a binary, but later studies could not find evidence for this claim. [8]

Physical properties

High levels of magnetic activity, a strong 6708Å lithium line, and the position on the color-magnitude diagram, slightly above the main sequence, strongly support a young age of the system. [12] The primary star is emitting a frequent and powerful (up to 5-8×1034 ergs) X-ray flares. [16]

Both components of the binary are main sequence stars. The primary has a mass very similar to the Sun, but slightly cooler and smaller, meaning it is only 72% as luminous as the Sun. The secondary is only 84% as massive as the Sun and only 33% as luminous.

Planetary system

The DS Tuc A planetary system [8] [12]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b<14.4 [9]   M🜨 0.18+0.13
−0.12		8.138268—88.73+0.18
−0.17 [9] ° 		5.70±0.17  R🜨

DS Tuc Ab is one of the few transiting planets with an age smaller than 100 Myrs. Other examples are K2-33b, V1298 Tauri b and AU Microscopii b. Of these systems DS Tuc is the brightest and it is a good target for atmospheric characterization with JWST. The planet is a super-Neptune or sub-Saturn. [8] The planet might be an inflated planet with an upper mass limit of 20 MEarth. [12] DS Tuc Ab will be observed by ESA's CHEOPS mission to characterize the planet. [17]

The planet DS Tucanae Ab has a low orbital obliquity (λ = 2.93° +0.88°
−0.87° or λ = 12°±13°). This means that the orbital plane of this planet aligns with the stellar equator of the star. This is unusual for a short period planet. Many short period planets show high orbital obliquity, which was taken as a sign of the scattering of the planet into this short period orbit. It can also be interpreted as the formation of a planet in an inner disk with an axial tilt. But these previous measurements of orbital obliquity were made for giant planets around mature stars. DS Tucanae Ab is a relatively small young planet. This suggests that DS Tucanae Ab formed in a smooth disk that was not perturbed by the stellar companion DS Tucanae B. [18] [19] DS Tucanae Ab might therefore be a good target to study in-situ planet-formation of short-period planets.

Related Research Articles

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<span class="mw-page-title-main">Alpha Tucanae</span> Binary star system in the constellation Tucana

Alpha Tucanae is a binary star system in the southern circumpolar constellation of Tucana. With an apparent visual magnitude of 2.86, it can be seen with the naked eye from the southern hemisphere. Using parallax measurements, the distance to this system can be estimated as 184 light-years. A cool star with a surface temperature of 4300 K, it is 424 times as luminous as the sun and 37 times its diameter. It is 2.5 to 3 times as massive. It is unclear what stage of evolution the star is in.

<span class="mw-page-title-main">Beta Tucanae</span> Star in the constellation Tucana

Beta Tucanae, Latinized from β Tucanae, is a group of six stars which appear to be at least loosely bound into a system in the constellation Tucana. Three of the stars are luminous and distinct enough to have been given their own Bayer designations, β1 Tucanae through β3 Tucanae. The system is approximately 140 light years from Earth.

<span class="mw-page-title-main">Eta Tucanae</span> Star in the constellation Tucana

Eta Tucanae, Latinized from η Tucanae, is a probable binary star system in the southern constellation of Tucana, a few degrees to the north of Epsilon Tucanae. It is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of +5.00. parallax measurements provide a distance estimate of about 154 light years from the Sun, and it is drifting further away with a mean radial velocity of +32.5 km/s. It is a member of the 30 million year old Tucana-Horologium association of co-moving stars.

Rho Tucanae is a binary star system in the southern constellation of Tucana. It is visible to the naked eye with a combined apparent visual magnitude of +5.38. Based upon an annual parallax shift of 24.37 mas as seen from Earth, it is located 131 light years from the Sun.

Lambda1 Tucanae is the Bayer designation for one member of a pair of stars sharing a common proper motion through space, which lie within the southern constellation of Tucana. As of 2013, the pair had an angular separation of 20.0 arc seconds along a position angle of 82°. Together, they are barely visible to the naked eye with a combined apparent visual magnitude of 6.21. Based upon an annual parallax shift for both stars of approximately 16.5 mas as seen from Earth, this system is located roughly 198 light years from the Sun.

Lambda2 Tucanae is a solitary star in the southern constellation of Tucana. It is faintly visible to the naked eye with an apparent visual magnitude of +5.45. Based upon an annual parallax shift of 14.6 mas as seen from Earth, it is located around 223 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.09 due to interstellar dust.

HD 142022 is a binary star system located in the southernmost constellation of Octans. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 7.70. The distance to this system is 112 light-years based on parallax, but it is drifting closer to the Sun with a radial velocity of −10 km/s.

<span class="mw-page-title-main">S Monocerotis</span> Star in the constellation Monoceros

S Monocerotis, also known as 15 Monocerotis, is a massive multiple and variable star system located in the constellation Monoceros. It is the brightest star in the Christmas Tree open cluster in the area catalogued as NGC 2264.

<span class="mw-page-title-main">V429 Geminorum</span> Star in the constellation Gemini

V429 Geminorum (BD+20°1790) is a young orange dwarf star in the constellation Gemini, located 90 light years away from the Sun. It is a BY Draconis variable, a cool dwarf which varies rapidly in brightness as it rotates.

HD 106515 is a binary star in the constellation of Virgo.

ADS 9731 is a star system that consists of six stars, located in the constellation of Corona Borealis. Four of the stars are visually separate in the sky, forming a visual star system, which was resolved using adaptive optics in 1995. Two of these stars were themselves found to be spectroscopic binaries in 1998, resulting in a total of six known stars in the system. It is one of very few multiple star systems known to have at least six members.

EQ Pegasi is a nearby binary system of two red dwarfs. Both components are flare stars, with spectral types of M4Ve and M6Ve respectively, and a current separation between the components of 5.8 arcseconds. The system is at a distance of 20.4 light-years, and is 950 million years old. The primary star is orbited by one known exoplanet.

<span class="mw-page-title-main">Tucana-Horologium association</span> Large stellar association

The Tucana-Horologium association (Tuc-Hor), or Tucana Horologium moving group, is a stellar association with an age of 45 ± 4 Myr and it is one of the largest stellar associations within 100 parsecs. The association has a similar size to the Beta Pictoris moving group (BPMG) and contains, like BPMG, more than 12 stars with spectral type B, A and F. The association is named after two southern constellations, the constellation Tucana and the constellation Horologium.

BD+00 316 is an ordinary star with a close-orbiting planetary companion in the equatorial constellation of Cetus. It is also known as WASP-71 since 2019; BD+00 316 is the stellar identifier from the Bonner Durchmusterung catalogue. With an apparent visual magnitude of 10.56, it is too faint to be visible to the naked eye. This star is located at a distance of 1,160 light-years based on parallax measurements, and is drifting further away with a heliocentric radial velocity of 7.7 km/s.

HD 44120 is a wide binary star system in the southern constellation of Pictor. Although visible to the naked eye, it is a challenge to view having an apparent visual magnitude of 6.44. The system is located at a distance of 118 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −2 km/s. It has an absolute magnitude of 3.57.

WASP-54, also known as BD+00 3088, is a binary star system about 825 light-years away. The primary, WASP-54A, is a F-type main-sequence star, accompanied by the red dwarf WASP-54B on a wide orbit. WASP-54 is depleted in heavy elements, having 55% of the solar abundance of iron. The age of WASP-54 is slightly older than the Sun's at 6.9+1.0
−1.9 billion years.

WASP-84, also known as BD+02 2056, is a G-type main-sequence star 327 light-years away in the constellation Hydra. Its surface temperature is 5350±31 K and is slightly enriched in heavy elements compared to the Sun, with a metallicity Fe/H index of 0.05±0.02. It is rich in carbon and depleted of oxygen. WASP-84's age is probably older than the Sun at 8.5+4.1
−5.5 billion years. The star appears to have an anomalously small radius, which can be explained by the unusually high helium fraction or by it being very young.

<span class="mw-page-title-main">GI Tauri and GK Tauri</span> Binary star system in the constellation of Taurus

GK Tauri is a young T Tauri-type pre-main sequence star in the constellation of Taurus about 421 light years away, belonging to the Taurus Molecular Cloud.

HD 3443 is a binary system composed of medium-mass main sequence stars in the constellation of Cetus about 50 light years away.

References

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  2. ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN   0004-6361.
  3. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  4. 1 2 3 Torres, G. (August 1988). "Visual Measurements of Southern Double Stars - Part Three". Astrophysics and Space Science. 147 (2): 257–266. Bibcode:1988Ap&SS.147..257T. doi:10.1007/BF00645670. ISSN   0004-640X. S2CID   116982206.
  5. 1 2 Samus', N. N.; Goranskii, V. P.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L. (July 2003). "An Electronic Version of the Second Volume of the General Catalogue of Variable Stars with Improved Coordinates". Astronomy Letters. 29 (7): 468–479. Bibcode:2003AstL...29..468S. doi:10.1134/1.1589864. ISSN   1063-7737. S2CID   16299532.
  6. ↑ 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.
  7. ↑ 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.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Newton, Elisabeth R.; et al. (July 2019). "TESS Hunt for Young and Maturing Exoplanets (THYME): A Planet in the 45 Myr Tucana-Horologium Association". The Astrophysical Journal Letters. 880 (1): L17. arXiv: 1906.10703 . Bibcode:2019ApJ...880L..17N. doi: 10.3847/2041-8213/ab2988 . hdl: 1721.1/124722 . ISSN   0004-637X. S2CID   195658207.
  9. 1 2 3 Benatti, S.; Damasso, M.; Borsa, F.; Locci, D.; Pillitteri, I.; Desidera, S.; Maggio, A.; Micela, G.; Wolk, S.; Claudi, R.; Malavolta, L.; Modirrousta-Galian, D. (2021), "Constraints on the mass and on the atmospheric composition and evolution of the low-density young planet DS Tucanae a B", Astronomy & Astrophysics, 650: A66, arXiv: 2103.12922 , Bibcode:2021A&A...650A..66B, doi:10.1051/0004-6361/202140416, S2CID   234864890
  10. ↑ Zuckerman, B.; Webb, R. A. (2000-06-01). "Identification of a Nearby Stellar Association in theHipparcos Catalog: Implications for Recent, Local Star Formation". The Astrophysical Journal. 535 (2): 959. arXiv: astro-ph/0002461 . Bibcode:2000ApJ...535..959Z. doi:10.1086/308897. ISSN   0004-637X. S2CID   2485534.
  11. ↑ Albright, Charlotte (14 August 2019). "Dartmouth Astronomer on Leading Discovery of a New Planet | Dartmouth News". news.dartmouth.edu. Retrieved 2022-01-30.
  12. 1 2 3 4 Benatti, S.; Nardiello, D.; Malavolta, L.; Desidera, S.; Borsato, L.; Nascimbeni, V.; Damasso, M.; D'Orazi, V.; Mesa, D.; Messina, S.; Esposito, M.; Bignamini, A.; Claudi, R.; Covino, E.; Lovis, C.; Sabotta, S. (October 2019). "A possibly inflated planet around the bright young star DS Tucanae A". Astronomy & Astrophysics. 630: A81. arXiv: 1904.01591 . Bibcode:2019A&A...630A..81B. doi:10.1051/0004-6361/201935598. ISSN   0004-6361. S2CID   102486551.
  13. ↑ "DS Tuc A b". exoplanetarchive.ipac.caltech.edu. Retrieved 2019-12-18.
  14. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  15. ↑ Torres, C. a. O.; Quast, G. R.; Silva, L. da; Reza, R. de la; Melo, C. H. F.; Sterzik, M. (2006-12-01). "Search for associations containing young stars (SACY) - I. Sample and searching method". Astronomy & Astrophysics. 460 (3): 695–708. arXiv: astro-ph/0609258 . Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN   0004-6361. S2CID   16080025.
  16. ↑ Pillitteri, I.; Argiroffi, C.; Maggio, A.; Micela, G.; Benatti, S.; Reale, F.; Colombo, S.; Wolk, S. J. (2022), "X-ray flares of the young planet host Ds Tucanae A", Astronomy & Astrophysics, 666: A198, arXiv: 2208.07415 , Bibcode:2022A&A...666A.198P, doi:10.1051/0004-6361/202244268, S2CID   251589568
  17. ↑ "AO-1 Programmes - CHEOPS Guest Observers Programme - Cosmos". www.cosmos.esa.int. Retrieved 2019-12-18.
  18. ↑ Montet, Benjamin T.; Feinstein, Adina D.; Luger, Rodrigo; Bedell, Megan E.; Gully-Santiago, Michael A.; Teske, Johanna K.; Xuesong Wang, Sharon; Butler, R. Paul; Flowers, Erin; Shectman, Stephen A.; Crane, Jeffrey D. (2020). "The Young Planet DS Tuc Ab has a Low Obliquity". The Astronomical Journal. 159 (3): 112. arXiv: 1912.03794 . Bibcode:2020AJ....159..112M. doi: 10.3847/1538-3881/ab6d6d . S2CID   208920990.
  19. ↑ Zhou, G.; Winn, J. N.; Newton, E. R.; Quinn, S. N.; Rodriguez, J. E.; Mann, A. W.; Rizzuto, A. C.; Vanderburg, A. M.; Huang, C. X.; Latham, D. W.; Teske, J. K. (2020). "A well aligned orbit for the 45 Myr old transiting Neptune DS Tuc Ab". The Astrophysical Journal. 892 (2): L21. arXiv: 1912.04095 . Bibcode:2020ApJ...892L..21Z. doi: 10.3847/2041-8213/ab7d3c . S2CID   208910672.
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