HD 28736

Last updated

HD 28736
Taurus constellation map.svg
Red circle.svg
Location of HD 28736 (circled)
Observation data
Epoch J2000        Equinox J2000
Constellation Taurus
HD 28736 A
Right ascension 04h 32m 04.80859s [1]
Declination +05° 24′ 36.1482″ [1]
Apparent magnitude  (V)6.352 [1]
HD 28736 C
Right ascension 04h 33m 56.59566s [2]
Declination +05° 37′ 23.5351″ [2]
Characteristics
Spectral type (F5V + L9-T1) + L0/1 [3]
B−V color index +0.431 [4]
J−H color index +0.208 [1]
J−K color index +0.260 [1]
Astrometry
HD 28736 A
Radial velocity (Rv)39.5813 ± 0.0216 [5]  km/s
Proper motion (μ)RA: 112.174 [6]   mas/yr
Dec.: 7.756 [6]   mas/yr
Parallax (π)23.1089 ± 0.0278  mas [6]
Distance 141.1 ± 0.2  ly
(43.27 ± 0.05  pc)
HD 28736 C
Proper motion (μ)RA: 107.173 [7]   mas/yr
Dec.: 7.595 [7]   mas/yr
Parallax (π)22.6203 ± 0.4505  mas
Distance 144 ± 3  ly
(44.2 ± 0.9  pc)
Orbit [3]
PrimaryHD 28736 A
CompanionHD 28736 B
Period (P)60+30
−16 yr
Semi-major axis (a)0.37"
(17+5
−4  AU )
Eccentricity (e)0.36+0.37
−0.25
Inclination (i)95.3+3.9
−2.1°
Orbit [3]
PrimaryHD 28736 A
CompanionHD 28736 C
Semi-major axis (a)1837"
(79000  AU )
Details [3]
HD 28736 A
Mass 1.40±0.05  M☉
Surface gravity (log g)4.3±0.2  cgs
Temperature 6655±125  K
Metallicity [Fe/H]0.13±0.05  dex
Rotational velocity (v sin i)45.6±1.8 km/s
Age 650±100  Myr
HD 28736 B
Mass 24+6
−4  MJup
Surface gravity (log g)4.5  cgs
Temperature 1300±50  K
HD 28736 C
Mass 73±7  MJup
Luminosity 2.40+0.23
−0.21×10−4  L☉
Other designations
HD 28736 AB: 58 G. Tauri, AG+05° 479, BD+05° 674, Gaia DR3  3285426613077584384, GC  5531, HD  28736, HIP  21152, HR  1436, SAO  111879, PPM  147652, TIC  452767166, TYC  90-33-1, GSC  00090-00033, 2MASS J04320481+0524359 [1] [8]
HD 28736 C: Gaia DR3  3285527699426683264, 2MASS J04335658+0537235, WISE J043356.65+053723.5 [2]
Database references
SIMBAD HD 28736

HD 28736 (HIP 21152, HR 1436) is a triple star system in the constellation of Taurus. It is composed of an F-type main-sequence star, an orbiting low-mass brown dwarf or giant planet, and a high-mass brown dwarf or low-mass star. Located some 141 light-years (43 parsecs) away according to Gaia EDR3 parallax measurements, it is a member of the Hyades cluster, moving away from Earth at a heliocentric radial velocity of 39.58 km/s. With an apparent magnitude of 6.352, it is near the limit for naked eye visibility under dark skies.

Contents

Stellar components

HD 28736 A

HD 28736 A is a young star, aged 650 ± 100 million years. This was estimated from the age of the Hyades cluster itself, [3] which is about 625 million years. [9] It is about 40% more massive than the Sun and also hotter at 6,655 K (6,382 °C; 11,519 °F).

The star is enriched in many elements heavier than hydrogen and helium compared to the Sun. In particular, the concentrations of strontium, barium, lanthanum, cerium, samarium, and gadolinium are at least 150% greater. A similar pattern is observed in other F-type dwarfs belonging to the cluster. [10]

HD 28736 B

In 2022, three teams of astronomers independently announced the discovery of a brown dwarf orbiting HD 28736 A via direct imaging, the first brown dwarf to be discovered by this method around main-sequence stars in the Hyades [3] [11] and the first substellar object of any kind to be found in the cluster to orbit stars with a spectral type of F, G, or K. [12]

The object, HD 28736 B, is near the border between L and T dwarfs, with an estimated spectral type of T0 ± 1. It has a mass of 24 MJ (~2% of the host star mass [11] ), substantially lower than evolutionary model predictions [3] and close to the planet-brown dwarf boundary. [11] Indeed, some organizations classify it as a planet instead, such as the NASA Exoplanet Science Institute, which includes the object in the NASA Exoplanet Archive [13] [lower-alpha 1] since it weighs less than 30 MJ. [14] It completes one orbit around the star every 60 years at a distance of 17 AU (2.5×10^9 km), slightly closer than Uranus is to the Sun (19.165 AU [15] ).

HD 28736 C

One of the teams that discovered HD 28736 B reported that another object, 2MASS J04335658+0537235, was found to be a co-moving companion to the HD 28736 system, at a very wide projected separation of 79,000 AU (1.25 ly) at the host star's distance. The 3D separation is even larger at 250000±140000 AU (4.0±2.2 ly), comparable to the distance between the Sun and Alpha Centauri. Despite this, there is a high likelihood that the object is gravitationally bound to the system. [3]

It has a mass of 73±7MJ, placing it right at the hydrogen burning limit. As such, it is uncertain whether the object is a massive brown dwarf or a low-mass star. [3]

Nearby interstellar clouds

Observations via the Space Telescope Imaging Spectrograph, installed on the Hubble Space Telescope, revealed three distinct velocity components in the interstellar absorption seen in HD 28736's spectra, specifically in the emission lines of doubly ionized magnesium. This corresponds to three interstellar clouds occupying the space between the system and Earth, all moving in different directions and speeds. [16]

The closest of the three is the Local Interstellar Cloud (LIC), which the Solar System is within and thus absorbs light emitted by all Hyades members. A secondary cloud, dubbed the Hyades Cloud, is located farther than the LIC and possesses a more filament-like structure, absorbing light from a substantial portion of Hyades stars. A third cloud has been identified that affects light from HD 28736 but not other stars in the vicinity, meaning it only covers a small patch of the sky and hence is probably situated farther away than the Hyades Cloud. [16]

Notes

  1. ↑ The NASA Exoplanet Archive lists the object as HIP 21152 b, rather than using the capital B.

Related Research Articles

<span class="mw-page-title-main">Hyades (star cluster)</span> Open cluster in the constellation Taurus

The Hyades is the nearest open cluster and one of the best-studied star clusters. Located about 153 light-years away from the Sun, it consists of a roughly spherical group of hundreds of stars sharing the same age, place of origin, chemical characteristics, and motion through space. From the perspective of observers on Earth, the Hyades Cluster appears in the constellation Taurus, where its brightest stars form a "V" shape along with the still-brighter Aldebaran. However, Aldebaran is unrelated to the Hyades, as it is located much closer to Earth and merely happens to lie along the same line of sight.

<span class="mw-page-title-main">Iota Horologii</span> Star in the constellation Horologium

Iota Horologii, Latinized from ι Horologii, is a yellow-hued star approximately 56.5 light-years away in the Horologium constellation. The star is classified as a G0Vp yellow dwarf. It has a mass and radius larger than the Sun, and is about 50% more luminous.

<span class="mw-page-title-main">HD 80606 and HD 80607</span> Binary star system in the constellation Ursa Major

HD 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binary system is listed as Struve 1341 in the Struve Catalogue of Double Stars; however, this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.

HD 222582 is a multiple star system in the equatorial constellation of Aquarius. It is invisible to the naked eye with an apparent visual magnitude of 7.7, but can be viewed with binoculars or a small telescope. The system is located at a distance of 137 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +12 km/s. It is located close enough to the ecliptic that it is subject to lunar occultations.

HD 154857 is a star with two exoplanetary companions in the southern constellation of Ara. It is too dim to be visible with the naked eye having an apparent visual magnitude of 7.25. The star is located at a distance of 207 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +28 km/s.

HD 117207 is a star in the southern constellation Centaurus. With an apparent visual magnitude of 7.24, it is too dim to be visible to the naked eye but can be seen with a small telescope. Based upon parallax measurements, it is located at a distance of 105.4 light-years from the Sun. The star is drifting closer with a radial velocity of −17.4 km/s. It has an absolute magnitude of 4.67.

HD 190228 is a star with an orbiting substellar companion in the northern constellation of Vulpecula. Its apparent magnitude is 7.30 – too faint to be seen with the naked eye – and the absolute magnitude is 3.34. Based on parallax measurements, it is located at a distance of 205 light-years from the Sun. The system is drifting closer with a radial velocity of −50 km/s.

<span class="mw-page-title-main">HD 13189</span> Orange-hued star in the constellation Taurus

HD 13189 is a star with an orbiting companion in the northern constellation of Triangulum constellation. With an apparent visual magnitude of +7.57, it is too faint to be visible to the normal human eye. The distance to this system is approximately 1,590 light years based on parallax measurements, and it is drifting further away with a radial velocity of 25.39 km/s. In 2005, a planetary companion or brown dwarf was announced in orbit around this star.

HD 162020 is a star in the southern constellation of Scorpius with a likely red dwarf companion. It has an apparent visual magnitude of 9.10, which is too faint to be visible to the naked eye. The distance to this system is 102 light-years based on stellar parallax. It is drifting closer to the Sun with a radial velocity of −27 km/s, and is predicted to come to within ~18 light-years in 1.1 million years.

<span class="mw-page-title-main">HD 85512</span> Star in the constellation Vela

HD 85512 is a solitary K-type main-sequence star 36.8 light-years away in the constellation Vela. It is about 1 billion years older than the Sun. It is extremely chromospherically inactive, only slightly more active than Tau Ceti. It exhibits a long-term variability and was thought to host one low-mass planet, although this is now doubtful.

<span class="mw-page-title-main">HD 7924</span> Star in the constellation Cassiopeia

HD 7924 is a single star located 55.5 light years away from the Sun in the northern constellation of Cassiopeia, near the northern constellation border with Cepheus. It has an orange hue and is only visible by means of binoculars or a telescope due to a low apparent visual magnitude of 7.167. The star is drifting closer to the Sun with a radial velocity of –22.7 km/s, and is expected to approach to within 9.3 light-years in around 711,700 years.

HD 5388 is a single star in the southern constellation of Phoenix. It has the Gould designation 78 G. Phoenicis, while HD 5388 is the star's Henry Draper Catalogue identifier. This object has a yellow-white hue and is too faint to be readily visible to average human eyesight, having an apparent visual magnitude of 6.73. It is located at a separation of 173 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +39 km/s.

HD 86226 is a star with a pair of orbiting exoplanet companions, found in the constellation of Hydra. With an apparent visual magnitude of 7.93, it is too dim to be visible with the naked eye. The distance to this system has been determined by the parallax method, yielding a range of 149 light years. It is receding with a heliocentric radial velocity of +19.6 km/s. A survey in 2015 has ruled out the existence of any stellar companions at projected distances above 12 astronomical units.

HD 191760 is a star in the southern constellation of Telescopium. It has a yellow hue but is too dim to be visible to the naked eye with an apparent visual magnitude of 8.26. The star is located at a distance of approximately 290 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −30 km/s.

HD 126053 is the Henry Draper Catalogue designation for a star in the equatorial constellation of Virgo. It has an apparent magnitude of 6.25, which means it is faintly visible to the naked eye. According to the Bortle scale, it requires dark suburban or rural skies to view. Parallax measurements made by the Hipparcos spacecraft provide an estimated distance of 57 light years to this star. It is drifting closer with a heliocentric radial velocity of −19.2 km/s.

<span class="mw-page-title-main">HD 131399</span> Star in the constellation Centaurus

HD 131399 is a star system in the constellation of Centaurus. Based on the system's electromagnetic spectrum, it is located around 350 light-years away. The total apparent magnitude is 7.07, but because of interstellar dust between it and the Earth, it appears 0.22 ± 0.09 magnitudes dimmer than it should be.

<span class="mw-page-title-main">HD 283750</span> Star in the constellation Taurus

HD 283750, also known as V833 Tauri, is a K-type main-sequence star 57 light-years away from the Sun. The star is much younger than the Sun's at 1 billion years. HD 283750 is similar to the Sun in its concentration of heavy elements.

HD 72945 and HD 72946 form a co-moving star system in the northern constellation of Cancer. HD 72945 is a binary star that is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.91. At an angular separation of 10.10″ is the fainter companion star HD 72946 at magnitude 7.25. It is being orbited by a brown dwarf. The system as a whole is located at a distance of approximately 84 light years from the Sun based on parallax measurements.

<span class="mw-page-title-main">HD 11343</span> K-type giant star in the constellation Eridanus

HD 11343 is a wide binary system between HD 11343 A, a K-type borderline giant star, and HD 11343 B, a red dwarf companion, located in the southern constellation of Eridanus about 500 light-years (150 pc) distant. Two gas giant exoplanets are known to orbit the primary star.

References

  1. 1 2 3 4 5 6 "HD 28736". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 1 November 2024.
  2. 1 2 3 "2MASS J04335658+0537235". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 1 November 2024.
  3. 1 2 3 4 5 6 7 8 9 Franson, Kyle; Bowler, Brendan P.; Bonavita, Mariangela; et al. (9 January 2023). "Astrometric Accelerations as Dynamical Beacons: Discovery and Characterization of HIP 21152 B, the First T-dwarf Companion in the Hyades*". The Astronomical Journal. 165 (2). American Astronomical Society: 39. arXiv: 2211.09840 . doi: 10.3847/1538-3881/aca408 . ISSN   0004-6256.
  4. ↑ Joner, Michael D.; Taylor, Benjamin J.; Laney, C. David; et al. (2 June 2006). "Homogeneous Photometry for the Hyades: Scale-Factor and Zero-Point Tests of Previously Published BV(RI)C Photometry". The Astronomical Journal. 132 (1). American Astronomical Society: 111–116. doi:10.1086/504410. ISSN   0004-6256.
  5. ↑ Leão, I C; Pasquini, L; Ludwig, H-G; de Medeiros, J R (29 November 2018). "Spectroscopic and astrometric radial velocities: Hyades as a benchmark". Monthly Notices of the Royal Astronomical Society. 483 (4). Oxford University Press (OUP): 5026–5041. arXiv: 1811.08771 . doi: 10.1093/mnras/sty3215 . ISSN   0035-8711.
  6. 1 2 3 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.
  7. 1 2 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.
  8. ↑ Pilcher, Frederick. "Uranometria Argentina". Archived from the original on 27 February 2012. Retrieved 1 November 2024.{{cite web}}: CS1 maint: unfit URL (link)
  9. ↑ Perryman, M.A.C.; et al. (1998). "The Hyades: distance, structure, dynamics, and age". Astronomy & Astrophysics. 331: 81–120. arXiv: astro-ph/9707253 . Bibcode:1998A&A...331...81P.
  10. ↑ Kılıçoǧlu, T.; Monier, R.; Gebran, M. (December 2015). Martins, F.; Boissier, S.; Buat, V.; Cambrésy, L.; Petit, P. (eds.). "Abundance Determinations for the F Dwarfs Members of the Hyades from SOPHIE High Resolution Spectra". Proceedings of the Annual Meeting of the French Society of Astronomy and Astrophysics: 389–392. Bibcode:2015sf2a.conf..389K.
  11. 1 2 3 Kuzuhara, Masayuki; Currie, Thayne; Takarada, Takuya; et al. (27 July 2022). "Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS*". The Astrophysical Journal Letters. 934 (2). American Astronomical Society: L18. arXiv: 2205.02729 . doi: 10.3847/2041-8213/ac772f . ISSN   2041-8205.
  12. ↑ Bonavita, M; Fontanive, C; Gratton, R; et al. (10 May 2022). "Results from The COPAINS Pilot Survey: Four new brown dwarfs and a high companion detection rate for accelerating stars". Monthly Notices of the Royal Astronomical Society. Oxford University Press (OUP). arXiv: 2205.02213 . doi: 10.1093/mnras/stac1250 . ISSN   0035-8711.
  13. ↑ "HIP 21152 Overview". NASA Exoplanet Archive . Retrieved 1 November 2024.
  14. ↑ "Exoplanet Criteria for Inclusion in the Archive". NASA Exoplanet Archive .
  15. ↑ Williams, Dr. David R. (31 January 2005). "Uranus Fact Sheet". NASA. Archived from the original on 13 July 2017. Retrieved 10 August 2007.
  16. 1 2 Redfield, Seth; Linsky, Jeffrey L. (10 April 2001). "Microstructure of the Local Interstellar Cloud and the Identification of the Hyades Cloud". The Astrophysical Journal. 551 (1). American Astronomical Society: 413–428. doi: 10.1086/320096 . ISSN   0004-637X.
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