HD 98800

Last updated
HD 98800
Observation data
Epoch J2000        Equinox J2000
Constellation Crater
HD 98800 A
Right ascension 11h 22m 05.287s [1]
Declination −24° 46′ 39.78″ [1]
Apparent magnitude  (V)9.59 [1]
HD 98800 B
Right ascension 11h 22m 05.288s [1]
Declination −24° 46′ 39.05″ [1]
Apparent magnitude  (V)10.06 [1] (10.4 / 11.5) [2]
Characteristics
HD 98800 A
Spectral type K5V / ? [3]
B−V color index 1.17 / ? [3]
HD 98800 B
Spectral type K7V / M1V [3]
B−V color index 1.37 / 1.41 [3]
Variable type T Tau / RS CVn? [4] [5] [6]
Astrometry
Proper motion (μ)RA: -85.40 [7]   mas/yr
Dec.: -33.10 [7]   mas/yr
Parallax (π)22.27 ± 2.31  mas [7]
Distance approx. 150  ly
(approx. 45  pc)
Absolute magnitude  (MV)6.06 (Aa) [3] 6.91 ± 0.26 [8] 8.02 ± 0.27 [8]
Orbit [9] [10]
PrimaryHD 98800 A
CompanionHD 98800 B
Period (P)246 ± 5 yr
Semi-major axis (a)1.471″
Eccentricity (e)0.5
Inclination (i)88.4 ± 2°
Longitude of the node (Ω)184.8°
Periastron epoch (T)2025
Argument of periastron (ω)
(secondary)		224.6°
Orbit [11]
PrimaryHD 98800 Aa
CompanionHD 98800 Ab
Period (P)264.51±0.02 d
Semi-major axis (a)0.86±0.02 AU
Eccentricity (e)0.4808±0.0008
Inclination (i)135.6±0.1°
Longitude of the node (Ω)170.2±0.1°
Periastron epoch (T) MJD 48742.5±0.8
Argument of periastron (ω)
(primary)		68.7±0.1°
Semi-amplitude (K1)
(primary)		6.7±0.2 km/s
Orbit [11]
PrimaryHD 98800 Ba
CompanionHD 98800 Bb
Period (P)314.86 ± 0.02 d
Semi-major axis (a)1.01±0.01 AU
Eccentricity (e)0.805 ± 0.005
Inclination (i)66.3±0.5°
Longitude of the node (Ω)342.7 ± 0.4°
Periastron epoch (T) MJD 48707.5 ± 0.2
Argument of periastron (ω)
(primary)		104.5 ± 0.3°
Semi-amplitude (K1)
(primary)		24.0 ± 0.3 km/s
Semi-amplitude (K2)
(secondary)		29.9 ± 0.6 km/s
Details
HD 98800 Aa
Mass 0.93±0.09 [11]   M☉
Radius 1.75 [12]   R☉
Surface gravity (log g)4.25 [12]   cgs
Temperature 4500 [12]   K
Rotational velocity (v sin i)5.0 [12]  km/s
Age 7 ± 5 [3]   Myr
HD 98800 Ab
Mass 0.29±0.02 [11]   M☉
HD 98800 Ba
Mass 0.77 ± 0.04 [11]   M☉
Radius 1.09 ± 0.14 [8]   R☉
Luminosity 0.330 ± 0.075 [8]   L☉
Surface gravity (log g)4.21 ± 0.12 [8]   cgs
Temperature 4200 ± 150 [8]   K
Rotational velocity (v sin i)3.0 [12]  km/s
HD 98800 Bb
Mass 0.62 ± 0.02 [11]   M☉
Radius 0.85 ± 0.11 [8]   R☉
Luminosity0.167 ± 0.038 [8]   L☉
Surface gravity (log g)4.34 ± 0.12 [8]   cgs
Temperature 4000 ± 150 [8]   K
Rotational velocity (v sin i)0.0 [12]  km/s
Other designations
TV Crt, CD−24° 9706, GJ  2084, HD  98800, HIP  55505, SAO  179815, ADS  8141 AB, CCDM J11221-2447AB
Database references
SIMBAD HD 98800
HD 98800A
HD 98800B
ARICNS HD 98800A
HD 98800B

HD 98800, also catalogued as TV Crateris (TV Crt), is a quadruple star system in the constellation of Crater (the cup). Parallax measurements made by the Hipparcos spacecraft put it at a distance of about 150 light-years (45 parsecs) away, [7] but this value is in high error. The system is located within the TW Hydrae association (TWA), and has received the designation TWA 4. [13]

Contents

The system consists of HD 98800 A and HD 98800 B each of which contains two stars. In 2007, a debris disk was discovered orbiting HD 98800 B consisting of two rings which indicates there may be an extrasolar planet orbiting within a distance of 1.5 to 2 astronomical units.

Stellar system

The system is a member of the TW Hydrae association, a group of young stars. Its membership was derived from the fact that its proper motion is similar to other stars in the group. [13] The system itself is estimated to be around 7-10 million years old. [14]

HD 98800 is a quadruple system, with two pairs of stars orbiting each other. The two pairs are separated by over an arcsecond, [10] so the wide visual orbit is poorly known. A preliminary range of orbits has been calculated, with an orbital period of 300 to 430 years, as well as a moderate eccentricity of 0.3 to 0.6. [10]

The primary component, HD 98800 A, is a K-type main-sequence star [3] with a varying radial velocity. This indicates the presence of another star orbiting it, but light from that star cannot be detected, so the system is a single-lined spectroscopic binary. The secondary system, HD 98800 B, is another spectroscopic binary, but double-lined since both stars (another K-type star and a red dwarf) can be directly detected. The stars in the HD 98800 are much larger than would be expected from their masses: at such a young age, these stars have not condensed into their normal size yet. [15]

Variability

A visual band light curve for TV Crateris, adapted from Henry et al. (1995) TVCrtLightCurve.png
A visual band light curve for TV Crateris, adapted from Henry et al. (1995)

The brightness of HD 98800 varies slightly between magnitudes 8.91 and 8.98, and it has been given the variable star designation TV Crateris. [4] The designation TV Crateris includes all four stars and it appears that both components A and B are variable. Component A varies with a period of 2.521 days which is thought to be its rotation period and it is classified as an RS Canum Venaticorum variable, a dwarf star with an uneven surface brightness that changes brightness as it rotates. Component B is thought to be a T Tauri star, a pre-main-sequence star surrounded by a disk. [17] It has been speculated that it is actually a post-T Tauri star and that the variations are caused by irregularities in the tilted disk intercepting the light from the star. [5]

Planetary system

Debris disk

An image of the debris disk around HD 98800 B by ALMA. The disk is misaligned with the orbital plane of the inner binary. HD 98800 B.png
An image of the debris disk around HD 98800 B by ALMA. The disk is misaligned with the orbital plane of the inner binary.

An infrared excess indicative of a debris disk was first discovered by IRAS. [18] Further observations of the system have been made using Keck [19] and the Spitzer Space Telescope. [20] The disk consists of two separate belts. The inner ring extends from a distance of 1.5 to 2 astronomical units from the barycenter of the central binary. The outer ring begins at approximately 5.9 astronomical units from the central binary, and extends out an undetermined distance. The gap between the two rings is ~3 astronomical units. The inner ring is thin, while the inner portion of the outer ring is dense.

Dr. Elise Furlan, leader of the Spitzer team that imaged this disk, concludes that the dust generated from the collision of rocky objects in the outer belt should eventually migrate toward the inner disk. But because the system is a double binary system, the dust particles do not evenly fill out the inner disk as expected.

The disk was imaged with ALMA and the high resolution image showed that the disk is likely misaligned with the orbit of the inner binary. The long period of the orbiting inner binary could be responsible for this misalignment and any circumbinary planet forming in this disk would be misaligned with the orbit of the inner binary. [21] [9] Based on VLA observations the disk extends from 3 to 5 astronomical units. The disk is more similar to a massive gas-rich protoplanetary disks than to a debris disks, which is unusual for this kind of age of a circumbinary disk. [22]

Possible planets

Debris disks are thought to constitute a phase in planetary formation. Because of the gap within the debris disk, the possibility of a planet within the system becomes even more likely. The detected gap could be caused by a unique gravitational relationship between the disk and a possible planet already begun to form, carving out a clear space in the disk. However, the gap could also be gravitational resonance effects of the four stars.

See also

Related Research Articles

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Crater is a small constellation in the southern celestial hemisphere. Its name is the latinization of the Greek krater, a type of cup used to water down wine. One of the 48 constellations listed by the second-century astronomer Ptolemy, it depicts a cup that has been associated with the god Apollo and is perched on the back of Hydra the water snake.

<span class="mw-page-title-main">Protoplanetary disk</span> Gas and dust surrounding a newly formed star

A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, because gases or other material may be falling from the inner edge of the disk onto the surface of the star. This process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called proplyds.

HD 38529 is a binary star approximately 138 light-years away in the constellation of Orion.

<span class="mw-page-title-main">Debris disk</span> Disk of dust and debris in orbit around a star

A debris disk, or debris disc, is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks are found around stars with mature planetary systems, including at least one debris disk in orbit around an evolved neutron star. Debris disks can also be produced and maintained as the remnants of collisions between planetesimals, otherwise known as asteroids and comets.

<span class="mw-page-title-main">HD 113766</span> Binary star in the constellation Centaurus

HD 113766 is a binary star system located 424 light years from Earth in the direction of the constellation Centaurus. The star system is approximately 10 million years old and both stars are slightly more massive than the Sun. The two are separated by an angle of 1.3 arcseconds, which, at the distance of this system, corresponds to a projected separation of at least 170 AU.

<span class="mw-page-title-main">HR 5553</span> Binary star system in the constellation Boötes

HR 5553 is a binary star system located thirty-eight light-years away from the Sun, in the northern constellation Boötes. It has the variable star designation DE Boötis, and is classified as an RS Canum Venaticorum variable that ranges in apparent visual magnitude from 5.97 down to 6.04, which is bright enough to be dimly visible to the naked eye. The system is drifting closer to the Sun with a radial velocity of −30 km/s, and is expected to come as close as 26.9 light-years in 210,000 years.

<span class="mw-page-title-main">HD 141569</span> Star in the constellation Libra

HD 141569 is an isolated Herbig Ae/Be star of spectral class A2Ve approximately 364 light-years away in the constellation of Libra. The primary star has two red dwarf companions at about nine arcseconds. In 1999, a protoplanetary disk was discovered around the star. A gap in the disk led to speculation about a possible extrasolar planet forming in the disk.

<span class="mw-page-title-main">Circumbinary planet</span> Planet that orbits two stars instead of one

A circumbinary planet is a planet that orbits two stars instead of one. The two stars orbit each other in a binary system, while the planet typically orbits farther from the center of the system than either of the two stars. In contrast, circumstellar planets in a binary system have stable orbits around one of the two stars, closer in than the orbital distance of the other star. Studies in 2013 showed that there is a strong hint that a circumbinary planet and its stars originate from a single disk.

<span class="mw-page-title-main">V4046 Sagittarii</span> Young binary star system in the constellation Sagittarius

V4046 Sagittarii is a young binary consisting of two K-type main-sequence stars. The two stars are about 271 light-years away from the Earth. The two stars orbit each other every 2.42 days on a circular orbit.

<span class="mw-page-title-main">HD 142527</span> Young star in the constellation of Lupus

HD 142527 is a binary star system in the constellation of Lupus. The primary star belongs to the Herbig Ae/Be star class, while the companion, discovered in 2012, is a red dwarf star or accreting protoplanet with a projected separation of less than 0.1″. The system is notable for its circumbinary protoplanetary disk and its discovery has helped refine models of planet formation. The orbit of companion is strongly inclined to the circumbinary protoplanetary disk.

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<span class="mw-page-title-main">HD 106906 b</span> Candidate exoplanet in the constellation Crux

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<span class="mw-page-title-main">HD 106906</span> Binary star in the constellation Crux

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<span class="mw-page-title-main">Circumstellar disc</span> Accumulation of matter around a star

A circumstellar disc is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the reservoirs of material out of which planets may form. Around mature stars, they indicate that planetesimal formation has taken place, and around white dwarfs, they indicate that planetary material survived the whole of stellar evolution. Such a disc can manifest itself in various ways.

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<span class="mw-page-title-main">RW Aurigae</span> Young binary star system in the constellation Auriga

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References

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  2. ↑ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 2017-08-01. Retrieved 2017-05-07.
  3. 1 2 3 4 5 6 7 Song, Inseok; Caillault, J.-P.; Barrado y Navascués, David; Stauffer, John R.; Randich, Sofia (April 2000), "Ages of Late Spectral Type Vega-like Stars", The Astrophysical Journal, 533 (1): L41–L44, arXiv: astro-ph/0002323 , Bibcode:2000ApJ...533L..41S, doi:10.1086/312597, PMID   10727387, S2CID   41394330
  4. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  5. 1 2 Verrier, P. E.; Evans, N. W. (2008). "HD 98800: A most unusual debris disc". Monthly Notices of the Royal Astronomical Society. 390 (4): 1377. arXiv: 0807.5105 . Bibcode:2008MNRAS.390.1377V. doi:10.1111/j.1365-2966.2008.13854.x. S2CID   119182238.
  6. ↑ "TV Crt". International Variable Star Index. Retrieved 2020-07-09.
  7. 1 2 3 4 van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600.
  8. 1 2 3 4 5 6 7 8 9 10 Boden, Andrew F.; Sargent, Anneila I.; Akeson, Rachel L.; Carpenter, John M.; Torres, Guillermo; Latham, David W.; Soderblom, David R.; Nelan, Ed; Franz, Otto G.; Wasserman, Lawrence H. (2005). "Dynamical Masses for Low-Mass Pre–Main-Sequence Stars: A Preliminary Physical Orbit for HD 98800 B". The Astrophysical Journal. 635 (1): 442–451. arXiv: astro-ph/0508331 . Bibcode:2005ApJ...635..442B. doi:10.1086/497328. S2CID   15698880.
  9. 1 2 Kennedy, Grant M.; Matrà, Luca; Facchini, Stefano; Milli, Julien; Panić, Olja; Price, Daniel; Wilner, David J.; Wyatt, Mark C.; Yelverton, Ben M. (February 2019). "Publisher Correction: A circumbinary protoplanetary disk in a polar configuration". Nature Astronomy. 3 (3): 278. arXiv: 1901.05018 . Bibcode:2019NatAs...3..278K. doi: 10.1038/s41550-019-0715-1 . ISSN   2397-3366.
  10. 1 2 3 Tokovinin, A. A. (1999). "The visual orbit of HD 98800". Astronomy Letters. 25 (10): 669–671. Bibcode:1999AstL...25..669T.
  11. 1 2 3 4 5 6 Zúñiga-Fernández, S.; Olofsson, J.; Bayo, A.; Haubois, X.; Corral-Santana, J. M.; Lopera-Mejía, A.; Ronco, M. P.; Tokovinin, A.; Gallenne, A.; Kennedy, G. M.; Berger, J.-P. (2021). "The HD 98800 quadruple pre-main sequence system" (PDF). Astronomy & Astrophysics. 655: A15. arXiv: 2109.02841 . doi:10.1051/0004-6361/202141985. S2CID   237431337.
  12. 1 2 3 4 5 6 Laskar, Tanmoy; Soderblom, David R.; Valenti, Jeff A.; Stauffer, John R. (2009). "The Metallicity of the Hd 98800 System". The Astrophysical Journal. 698 (1): 660–665. arXiv: 0905.1907 . Bibcode:2009ApJ...698..660L. doi:10.1088/0004-637X/698/1/660. S2CID   15230160.
  13. 1 2 Gagné, Jonathan; Faherty, Jacqueline K.; Mamajek, Eric E.; Malo, Lison; Doyon, René; Filippazzo, Joseph C.; Weinberger, Alycia J.; Donaldson, Jessica K.; Lépine, Sébastien; Lafrenière, David; Artigau, Étienne; Burgasser, Adam J.; Looper, Dagny; Boucher, Anne; Beletsky, Yuri; Camnasio, Sara; Brunette, Charles; Arboit, Geneviève (2017). "BANYAN. IX. The Initial Mass Function and Planetary-mass Object Space Density of the TW Hya Association". The Astrophysical Journal Supplement Series. 228 (2): 18. arXiv: 1612.02881 . Bibcode:2017ApJS..228...18G. doi: 10.3847/1538-4365/228/2/18 . S2CID   118920136.
  14. ↑ Ribas, Álvaro; Macías, Enrique; Espaillat, Catherine C.; Duchêne, Gaspard (2018). "Long-lived Protoplanetary Disks in Multiple Systems: The VLA View of HD 98800". The Astrophysical Journal. 865 (1): 77. arXiv: 1808.02493 . Bibcode:2018ApJ...865...77R. doi: 10.3847/1538-4357/aad81b . S2CID   118912551.
  15. ↑ "Encyclopedia of Science: T Tauri star". Archived from the original on 27 January 2021. Retrieved 17 January 2017.
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  17. ↑ Messina, S.; Desiderata, S.; Taratto, M.; Lanzafame, A. C.; Guinan, E. F. (September 2010). "RACE-OC project: Rotation and variability of young stellar associations within 100 pc". Astronomy and Astrophysics . 520: 63. arXiv: 1004.1959 . Bibcode:2010A&A...520A..15M. doi:10.1051/0004-6361/200913644. S2CID   118569400.
  18. ↑ Walker and Wolstencroft (1988). "Cool circumstellar matter around nearby main-sequence stars". Publications of the Astronomical Society of the Pacific . 100: 1509–1521. Bibcode:1988PASP..100.1509W. doi: 10.1086/132357 .
  19. ↑ Koerner; Jensen, E. L. N.; Cruz, K. L.; Guild, T. B.; Gultekin, K. (2000). "A Single Circumbinary Disk in the HD 98800 Quadruple System". The Astrophysical Journal. 533 (1): L37–L40. arXiv: astro-ph/0002227 . Bibcode:2000ApJ...533L..37K. doi:10.1086/312593. PMID   10727386. S2CID   17714246.
  20. ↑ Furlan, E.; et al. (2007). "HD 98800: A 10 Myr Old Transition Disk". The Astrophysical Journal. 664 (2): 1176–1184. arXiv: 0705.0380 . Bibcode:2007ApJ...664.1176F. doi:10.1086/519301. S2CID   14027663.
  21. ↑ Czekala, Ian; Chiang, Eugene; Andrews, Sean M.; Jensen, Eric L. N.; Torres, Guillermo; Wilner, David J.; Stassun, Keivan G.; Macintosh, Bruce (September 2019). "The Degree of Alignment between Circumbinary Disks and Their Binary Hosts". Astrophysical Journal. 883 (1): 22. arXiv: 1906.03269 . Bibcode:2019ApJ...883...22C. doi: 10.3847/1538-4357/ab287b . ISSN   0004-637X. S2CID   182952526.
  22. ↑ Ribas, Álvaro; Macías, Enrique; Espaillat, Catherine C.; Duchêne, Gaspard (September 2018). "Long-lived Protoplanetary Disks in Multiple Systems: The VLA View of HD 98800". Astrophysical Journal. 865 (1): 77. arXiv: 1808.02493 . Bibcode:2018ApJ...865...77R. doi: 10.3847/1538-4357/aad81b . ISSN   0004-637X.
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