HD 45166

Last updated • 3 min readFrom Wikipedia, The Free Encyclopedia
HD 45166
Observation data
Epoch J2000        Equinox J2000
Constellation Monoceros
Right ascension 06h 26m 19.155s [1]
Declination +07° 58 28.06 [1]
Apparent magnitude  (V)9.88 [2]
Characteristics
Spectral type qWR + B7V [3]
U−B color index −0.76 [4]
B−V color index −0.07 [4]
Variable type suspected
Astrometry
Proper motion (μ)RA: −0.389 [1]   mas/yr
Dec.: −0.339 [1]   mas/yr
Parallax (π)0.9955 ± 0.0346  mas [1]
Distance 991 [3]   pc
Orbit [3]
Period (P)8,200 days
Semi-major axis (a)10.5 AU
Eccentricity (e)0.46
Inclination (i)49±11°
Argument of periastron (ω)
(secondary)
132±11°
Semi-amplitude (K1)
(primary)
5.8±1.3 (B-type star) km/s
Details [3]
qWR
Mass 2.03±0.44  M
Radius 0.88±0.11  R
Luminosity 6760±830  L
Temperature 56000±6000  K
Rotation 124.82±0.21 days
Age 105  Myr
B7V
Mass 3.40±0.06  M
Radius 2.63±0.41  R
Luminosity178±22  L
Temperature 13000±500  K
Age 105  Myr
Other designations
TYC 732-754-1, ALS 8946, BD+08 1332, 2MASS J06261915+0758280
Database references
SIMBAD data

HD 45166 is a binary consisting of a so-called quasi Wolf–Rayet (qWR) star and a B-type main-sequence star, near the cluster NGC 2244, in the constellation of Monoceros. [5] A quasi Wolf–Rayet star is a star with a spectrum resembling those of true Wolf–Rayet stars, but being less massive and luminous than a true Wolf–Rayet star. The primary of HD 45166 is currently the only known example of a qWR star.

Contents

In 2023, the primary of HD 45166 was also found to be extremely magnetic, the most magnetic massive star known. It is currently the only Wolf-Rayet star in which a significant magnetic field was measured. It has a magnetic field strength of up to 43 kG, or about 43,000 times the Sun's magnetic field strength. This means that it is likely that when it dies in a type Ib/IIb supernova, the remnant will be a magnetar. [3]

Properties

Artist's impression of HD 45166 HD 45166 artist's impression (NOIRLab).jpg
Artist's impression of HD 45166

HD 45166 is currently a wide binary made up of a hot, small quasi Wolf–Rayet star and a larger B-type star, with masses of 2.03 M and 3.4 M respectively. They are separated by approximately 10.5 AU and orbit each other every 8200 days, or every 22.5 years. The orbit is moderately eccentric, and inclined from our view at about 49°. The HD 45166 system is estimated to be around 105 million years old. [3] The orbital period was formerly thought to have been 1.6 days, which would have made the primary about 4 M, but a 2023 study instead identified this signal as a pulsation mode of the secondary. [6]

The primary qWR star is slightly smaller than the Sun, with a surface temperature of 56,000 K. It is also mostly composed of helium, and is only composed of about 25% hydrogen. Some carbon, nitrogen and oxygen is also present in the star.

The B-type star is about two and a half times the size of the Sun, and has a temperature of about 13,000 K. [3]

Evolution

It is hard to explain the existence of the exotic qWR primary in HD 45166. A stellar merger from white dwarfs is extremely unstable, and would explode after about 10,000 years. Therefore, the most likely scenario for the creation of the qWR primary would be the merger of two helium stars in a tight binary.

The system likely formed as a triple star system, with a tight inner binary and a distant third star, which is now the B-type secondary star. In the tight binary, the more massive star expanded, and lost its outer layers via mass transfer to the secondary star, becoming a helium star. The same thing then happened to the secondary star of the tight binary, and so both stars became helium stars. Due to unstable mass transfer, a gaseous envelope formed around the two stars, causing them to lose orbital energy via friction, spiral inwards and eventually collide. This merger formed the quasi Wolf–Rayet primary of HD 45166 that we observe today. [3]

Future evolution

The qWR primary of HD 45166 is currently burning helium in its core. After it has exhausted this, it will likely start shell burning, and expand, forming a supergiant of about 300 R (well within its roche lobe). Then, it will explode in a type Ib or IIb supernova. The remnant will be a neutron star, probably also with a very strong magnetic field, i.e. a magnetar. [3]

Related Research Articles

<span class="mw-page-title-main">Wolf–Rayet star</span> Heterogeneous class of stars with unusual spectra

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.

<span class="mw-page-title-main">WR 136</span> Star in the constellation of Cygnus

WR 136 is a Wolf–Rayet star located in the constellation Cygnus. It is in the center of the Crescent Nebula. Its age is estimated to be around 4.7 million years and it is nearing the end of its life. Within a few hundred thousand years, it is expected to explode as a supernova.

<span class="mw-page-title-main">HD 5980</span> Triple star system in the constellation Tucana

HD 5980 is a multiple star system on the outskirts of NGC 346 in the Small Magellanic Cloud (SMC) and is one of the brightest stars in the SMC.

<span class="mw-page-title-main">WR 22</span> Binary star in the constellation Carina

WR 22, also known as V429 Carinae or HR 4188, is an eclipsing binary star system in the constellation Carina. The system contains a Wolf-Rayet (WR) star that is one of the most massive and most luminous stars known, and is also a bright X-ray source due to colliding winds with a less massive O class companion. Its eclipsing nature and apparent magnitude make it very useful for constraining the properties of luminous hydrogen-rich WR stars.

<span class="mw-page-title-main">WR 25</span> Binary star system in the constellation Carina

WR 25 is a binary star system in the turbulent star-forming region the Carina Nebula, about 6,800 light-years from Earth. It contains a Wolf-Rayet star and a hot luminous companion and is a member of the Trumpler 16 cluster. The name comes from the Catalogue of Galactic Wolf–Rayet Stars.

WR 147 is a multiple star system in the constellation of Cygnus. The system is extremely reddened by interstellar extinction – that is, dust in front of the star scatters much of the blue light coming from WR 147, leaving the star appearing reddish.

<span class="mw-page-title-main">WR 148</span> Binary star in the constellation of Cygnus

WR 148 is a spectroscopic binary in the constellation Cygnus. The primary star is a Wolf–Rayet star and one of the most luminous stars known. The secondary has been suspected of being a stellar-mass black hole but may be a class O main sequence star.

<span class="mw-page-title-main">CD Crucis</span> Eclipsing binary star system in the constellation Crux

CD Crucis, also known as HD 311884, is an eclipsing binary star system in the constellation Crux. It is around 14,000 light years away near the faint open cluster Hogg 15. The binary contains a Wolf–Rayet star and is also known as WR 47.

<span class="mw-page-title-main">AB8 (star)</span> Binary star located in the Small Magellanic Cloud in the constellation Hydrus

AB8, also known as SMC WR8, is a binary star in the Small Magellanic Cloud (SMC). A Wolf-Rayet star and a main sequence companion of spectral type O orbit in a period of 16.638 days. It is one of only nine known WO stars, the only Wolf-Rayet star in the SMC not on the nitrogen sequence, and the only Wolf-Rayet star in the SMC outside the main bar.

<span class="mw-page-title-main">WR 30a</span> Binary star in the constellation Carina

WR 30a is a massive spectroscopic binary in the Milky Way galaxy, in the constellation Carina. The primary is an extremely rare star on the WO oxygen sequence and the secondary a massive class O star. It appears near the Carina Nebula but is much further away.

<span class="mw-page-title-main">WR 137</span> Star in the constellation of Cygnus

WR 137 is a variable Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cygnus.

<span class="mw-page-title-main">WR 140</span> Star in the constellation of Cygnus

WR 140 is a visually moderately bright Wolf–Rayet star placed within the spectroscopic binary star, SBC9 1232, whose primary star is an evolved spectral class O4–5 star. It is located in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by Deneb, γ Cygni and δ Cygni.

<span class="mw-page-title-main">WR 9</span> Spectroscopic binary star system in the constellation Puppis

WR 9 is a spectroscopic binary in the constellation Puppis consisting of a Wolf-Rayet star and a class O star. It is around 12,000 light years away.

<span class="mw-page-title-main">WR 133</span> Wolf-Rayet star and spectroscopic binary star in the constellation of Cygnus

WR 133 is a visually moderately bright Wolf-Rayet star. It is a spectroscopic binary system containing a Wolf-Rayet primary and a class O supergiant secondary. It is in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by β and γ Cygni, near η Cygni. It is the brightest member of the sparse open cluster NGC 6871.

<span class="mw-page-title-main">WR 128</span> Wolf-Rayet star in the constellation Sagitta

WR 128 is a Wolf–Rayet star located about 9,500 light years away in the constellation of Sagitta. A member of the WN class, WR 128's spectrum resembles that of a WN4 star, but hydrogen is clearly present in the star, making it the only known hydrogen-rich WN4 star in the galaxy. However, similar H-rich very early WN stars can be found in the LMC and especially in the SMC, but the only other galactic examples of this are WR 3 and WR 152.

WR 69 is a Wolf–Rayet star located 11,350 light years away in the constellation of Triangulum Australe. It is classified as a WC9 star, belonging to the late-type carbon sequence. WR 69 is also a prolific dust maker, hence the "d" in its spectral type.

WR 150 is a Wolf-Rayet star in the constellation of Cygnus. It is one of the early-type carbon sequence (WCE), and is of spectral type WC5. WR 150 is very far from the Earth, being 28,500 light-years from it.

<span class="mw-page-title-main">WR 120</span> Binary star system in the constellation Scutum

WR 120 is a binary containing two Wolf-Rayet stars in the constellation of Scutum, around 10,000 light years away. The primary is a hydrogen-free weak-lined WN7 star, the secondary is a hydrogen-free WN3 or 4 star, and the system is a possible member of the cluster Dolidze 33. From our point of view, WR 120 is reddened by 4.82 magnitudes, and it has the variable designation of V462 Scuti.

<span class="mw-page-title-main">HD 326823</span> Binary star system in the constellation of Scorpius

HD 326823, also known as V1104 Scorpii, is a binary star containing a unique emission-line star, which is in the midst of transitioning to a nitrogen-rich Wolf-Rayet star, as well as being a candidate Luminous blue variable, located 4,142 light years away in the constellation of Scorpius. The primary is very evolved, because it is composed of almost entirely helium, and only 3% of it is still hydrogen, and it has lost most of its mass to the now-very-massive secondary. The underlying mechanisms and mass transfers in the system are comparable to other W Serpentis systems, such as Beta Lyrae and RY Scuti.

<span class="mw-page-title-main">CV Serpentis</span>

CV Serpentis is a binary star system in the equatorial constellation of Serpens. It is a detached eclipsing binary with an orbital period of 29.7 days. The system includes a Wolf–Rayet (WR) star with the identifier WR 113. The system is located at a distance of approximately 6,700 light years from the Sun based on parallax measurements. It is a member of the Serpens OB2 association of co-moving stars.

References

  1. 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.
  2. "HD 45166". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2023-08-18.
  3. 1 2 3 4 5 6 7 8 9 Shenar, Tomer; Wade, Gregg A.; Marchant, Pablo; Bagnulo, Stefano; Bodensteiner, Julia; Bowman, Dominic M.; Gilkis, Avishai; Langer, Norbert; Nicolas-Chené, André; Oskinova, Lidia; Van Reeth, Timothy; Sana, Hugues; St-Louis, Nicole; de Oliveira, Alexandre Soares; Todt, Helge (2023-08-18). "A massive helium star with a sufficiently strong magnetic field to form a magnetar". Science . 381 (6659): 761–765. arXiv: 2308.08591 . Bibcode:2023Sci...381..761S. doi:10.1126/science.ade3293. ISSN   0036-8075. PMID   37590342. S2CID   260956281.
  4. 1 2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR Online Data Catalog . 2237. Bibcode:2002yCat.2237....0D.
  5. Hoag, Arthur A.; Smith, Elske V. P. (February 1959). "Polarization in NGC2244". Publications of the Astronomical Society of the Pacific . 71 (418): 32. Bibcode:1959PASP...71...32H. doi: 10.1086/127327 . S2CID   123076673.
  6. Timmer, John (17 August 2023). "Heavy, highly magnetic star may be first magnetar precursor we've seen". Ars Technica .