CW Leonis

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CW Leonis
CW Leonis UV.jpg
CW Leonis in ultraviolet showing the bowshock
Observation data
Epoch J2000       Equinox J2000
Constellation Leo
Right ascension 09h 47m 57.406s [1]
Declination +13° 16′ 43.56″ [1]
Apparent magnitude  (V)14.5 (var.) [2]
Characteristics
Spectral type C9,5e [3]
Apparent magnitude  (R)10.96 [1]
Apparent magnitude  (J)7.34 [1]
Apparent magnitude  (H)4.04 [1]
Apparent magnitude  (K)1.19 [1]
Variable type Mira [4]
Astrometry
Proper motion (μ)RA: 35±1  mas/yr
Dec.: 12±1 [5]   mas/yr
Parallax (π)10.56 ± 2.02  mas [6]
Distance approx. 310  ly
(approx. 90  pc)
Details
Mass 0.7 - 0.9 [5]   M☉
Radius 560 [7]   R☉
Luminosity 8,500 (average), 11,850 (maximum) [7]   L☉
Temperature 2,300 [7] (1,915 - 2,105) [8]   K
Other designations
CW  Leo, Peanut Nebula, IRC+10216, IRAS  09452+1330, PK  221+45 1, Zel 0945+135, RAFGL  1381, 2MASS  J09475740+1316435, SCM 50 [9]
Database references
SIMBAD data

CW Leonis or IRC +10216 is a variable carbon star that is embedded in a thick dust envelope. It was first discovered in 1969 by a group of astronomers led by Eric Becklin, based upon infrared observations made with the 62-inch Caltech Infrared Telescope at Mount Wilson Observatory. Its energy is emitted mostly at infrared wavelengths. At a wavelength of 5  μm, it was found to have the highest flux of any object outside the Solar System. [10]

Contents

Properties

A LINEAR (white-light) light curve for CW Leonis, adapted from Palaversa et al. (2013) CWLeoLightCurve.png
A LINEAR (white-light) light curve for CW Leonis, adapted from Palaversa et al. (2013)

CW Leonis is believed to be in a late stage of its life, blowing off its own sooty atmosphere to form a white dwarf. Based upon isotope ratios of magnesium, the initial mass of this star has been constrained to lie between 3–5 solar masses. The mass of the star's core, and the final mass of the star once it becomes a white dwarf, is about 0.7–0.9 solar masses. [12] Its bolometric luminosity varies over the course of a 649-day pulsation cycle, ranging from a minimum of about 6,250 times the Sun's luminosity up to a peak of around 15,800 times. The overall output of the star is best represented by a luminosity of 11,300  L☉. [13] The brightness of the star varies by about two magnitudes over its pulsation period, and may have been increasing over a period of years. One study finds an increase in the mean brightness of about a magnitude between 2004 and 2014. [14] Many studies of this star are done at infrared wavelengths because of its very red colour; published visual magnitudes are uncommon and often dramatically different. The Guide Star Catalog from 2006 gives an apparent visual magnitude of 19.23. [15] The ASAS-SN variable star catalog based on observations from 2014 to 2018 reports a mean magnitude of 17.56 and an amplitude of 0.68 magnitudes. [16] An even later study gives a mean magnitude of 14.5 and an amplitude of 2.0 magnitudes. [2]

The carbon-rich gaseous envelope surrounding this star is at least 69,000 years old and the star is losing about (1–4) × 10−5 solar masses per year. [13] The extended envelope contains at least 1.4 solar masses of material. [17] Speckle observations from 1999 show a complex structure to this dust envelope, including partial arcs and unfinished shells. This clumpiness may be caused by a magnetic cycle in the star that is comparable to the solar cycle in the Sun and results in periodic increases in mass loss. [18]

Various chemical elements and about 50 molecules have been detected in the outflows from CW Leonis, among others nitrogen, oxygen and water, silicon, and iron. One theory was that the star was once surrounded by comets that melted once the star started expanding, [19] but water is now thought to form naturally in the atmospheres of all carbon stars. [20]

Distance

CW Leonis glows from deep within a thick shroud of dust in this image from the NASA/ESA Hubble Space Telescope. CW Leonis - HST - Heic2112a.jpg
CW Leonis glows from deep within a thick shroud of dust in this image from the NASA/ESA Hubble Space Telescope.

If the distance to this star is assumed to be at the lower end of the estimate range, 120 pc, then the astrosphere surrounding the star spans a radius of about 84,000  AU. The star and its surrounding envelope are advancing at a velocity of more than 91 km/s through the surrounding interstellar medium. [17] It is moving with a space velocity of [U, V, W] = [21.6 ± 3.9, 12.6 ± 3.5, 1.8 ± 3.3] km s−1. [12]

Companion

Several papers have suggested that CW Leonis has a close binary companion. [14] ALMA and astrometric measurements may show orbital motion. The astrometric measurements, combined with a model including the companion, provide a parallax measurement showing that CW Leonis is the closest carbon star to the Earth. [6]

See also

Related Research Articles

<span class="mw-page-title-main">Mira variable</span> Type of variable star

Mira variables are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths. They are red giants in the very late stages of stellar evolution, on the asymptotic giant branch (AGB), that will expel their outer envelopes as planetary nebulae and become white dwarfs within a few million years.

<span class="mw-page-title-main">Asymptotic giant branch</span> Stars powered by fusion of hydrogen and helium in shell with an inactive core of carbon and oxygen

The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) late in their lives.

<span class="mw-page-title-main">46 Leonis Minoris</span> Star in the constellation of Leo Minor

46 Leonis Minoris, also named Praecipua, is the brightest star in the constellation of Leo Minor. It is of spectral class K0+III-IV and of magnitude 3.83. It is a red clump giant. Based upon parallax measurements, its distance from the Sun is approximately 99.1 light-years. It is a suspected variable with an amplitude of about 0.05 magnitudes.

<span class="mw-page-title-main">UU Aurigae</span> Star in the constellation of Auriga

UU Aurigae is a carbon star in the constellation Auriga. It is approximately 341 parsecs from Earth.

<span class="mw-page-title-main">AD Leonis</span> M-type star in the constellation Leo

AD Leonis (Gliese 388) is a red dwarf star. It is located relatively near the Sun, at a distance of 16.2 light-years, in the constellation Leo. AD Leonis is a main sequence star with a spectral classification of M3.5V. It is a flare star that undergoes random increases in luminosity.

<span class="mw-page-title-main">Rho Leonis</span> Variable Star in the constellation Leo

Rho Leonis is a binary star in the zodiac constellation of Leo, and, like the prominent nearby star Regulus, is near the ecliptic. With an apparent visual magnitude of 3.9, this star can be readily seen with the naked eye. Spectroscopic measurements give a distance estimate of about 2,930 light-years from the Earth. Rho Leonis is an Alpha Cygni-type variable star, showing 0.032 magnitude brightness variations with a period of 3.427 days, in Hipparcos data.

<span class="mw-page-title-main">11 Leonis Minoris</span> Star in the constellation Leo Minor

11 Leonis Minoris is a binary star located 36.64 light years away from Earth, in the northern constellation of Leo Minor. It is visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.54. The system is moving away from the Earth with a heliocentric radial velocity of +14.4 km/s. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.764 arc seconds per annum.

<span class="mw-page-title-main">V Aquilae</span> Star in the constellation Aquila

V Aquilae is a carbon star and semiregular variable star in the constellation Aquila. It has an apparent magnitude which varies between 6.6 and 8.4 and is located around 400 parsecs (1,300 ly) away.

<span class="mw-page-title-main">V Hydrae</span> Variable star in the constellation Hydra

V Hydrae is a carbon star in the constellation Hydra. To date perhaps uniquely in our galaxy it has plasma ejections/eruptions on a grand scale that could be caused by its near, unseen companion.

<span class="mw-page-title-main">U Camelopardalis</span> Star in the constellation Camelopardalis

U Camelopardalis is a semiregular variable star in the constellation Camelopardalis. Based on parallax measurements made by the Hipparcos spacecraft, it is located about 3,000 light-years away from the Earth. Its apparent visual magnitude is about 8, which is dim enough that it cannot be seen with the unaided eye.

<span class="mw-page-title-main">RY Sagittarii</span> Yellow supergiant star in the constellation Sagittarius

RY Sagittarii is a yellow supergiant and an R Coronae Borealis type variable star in the constellation Sagittarius. Although it ostensibly has the spectrum of a G-type star, it differs markedly from most in that it has almost no hydrogen and much carbon.

<span class="mw-page-title-main">RS Telescopii</span> Star in the constellation Telescopium

RS Telescopii, abbreviated RS Tel, is a variable star in the southern constellation of Telescopium. It is a dim star with an apparent visual magnitude of 10.67, which is much too faint to be visible without a telescope. The variability of this star was discovered by Evelyn F. Leland and announced by Edward C. Pickering in 1910. It was first studied by Cecilia H. Payne in 1928 at the Harvard College Observatory.

<span class="mw-page-title-main">V Coronae Australis</span> Variable star in the constellation Corona Australis

V Coronae Australis is a R Coronae Borealis variable (RCB) star in the constellation Corona Australis. These are extremely hydrogen-deficient supergiants thought to have arisen as the result of the merger of two white dwarfs; fewer than 100 have been discovered as of 2012. V Coronae Australis dimmed in brightness from 1994 to 1998.

<span class="mw-page-title-main">LP Andromedae</span> Star in the constellation Andromeda

LP Andromedae is a carbon star in the constellation Andromeda. It is also a Mira variable whose mean apparent visual magnitude is 15.12 and has pulsations with an amplitude of 1.50 magnitudes and a period of 614 days.

<span class="mw-page-title-main">R Fornacis</span> Variable star in the constellation Fornax

R Fornacis is a Mira variable and carbon star located in the constellation Fornax. It is around 1,800 light years away based on parallax measurements.

<span class="mw-page-title-main">EP Aquarii</span> Variable star in the constellation Aquarius

EP Aquarii is a semiregular variable star in the equatorial constellation of Aquarius. At its peak brightness, visual magnitude 6.37, it might be faintly visible to the unaided eye under ideal observing conditions. A cool red giant on the asymptotic giant branch (AGB), its visible light brightness varies by about 1/2 magnitude over a period of 55 days. EP Aquarii has a complex circumstellar envelope (CSE), which has been the subject of numerous studies.

<span class="mw-page-title-main">CIT 6</span> Carbon star in the constellation Leo Minor

CIT 6 is a carbon star in the constellation Leo Minor. It is a semiregular variable star, with a period of about 628 days, and has been given the variable star designation RW Leonis Minoris. It is perhaps the second most studied carbon star, after CW Leonis. CIT 6 was discovered in 1966 by a group at the California Institute of Technology who found it using the same 62-inch infrared telescope on Mount Wilson that was used to produce the Two-Micron Sky Survey. It is the second brightest carbon star in the near-infrared, after CW Leonis.

<span class="mw-page-title-main">56 Leonis</span> Variable star in the constellation Leo

56 Leonis is a red giant variable star located approximately 390 light years away in the constellation Leo.

References

  1. 1 2 3 4 5 6 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  2. 1 2 Gigoyan, K. S.; Kostandyan, G. R.; Gigoyan, K. K.; Sarkissian, A.; Meftah, M.; Russeil, D.; Zamkotsian, F.; Rahmatullaeva, F. D.; Paronyan, G. (2021). "Investigations of the Periodic Variables in the Catalina and Linear Databases". Astrophysics. 64 (1): 20. Bibcode:2021Ap.....64...20G. doi:10.1007/s10511-021-09664-5. S2CID   254251265.
  3. ↑ Cohen, M. (1979). "Circumstellar envelopes and the evolution of carbon stars". Monthly Notices of the Royal Astronomical Society. 186 (4): 837–852. Bibcode:1979MNRAS.186..837C. doi: 10.1093/mnras/186.4.837 .
  4. ↑ 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. Bibcode:2009yCat....102025S.
  5. 1 2 Matthews, L. D.; Gérard, E.; Le Bertre, T. (2015). "Discovery of a shell of neutral atomic hydrogen surrounding the carbon star IRC+10216". Monthly Notices of the Royal Astronomical Society. 449 (1): 220–233. arXiv: 1502.02050 . Bibcode:2015MNRAS.449..220M. doi: 10.1093/mnras/stv263 . S2CID   96460867.
  6. 1 2 Sozzetti, A.; Smart, R. L.; Drimmel, R.; Giacobbe, P.; Lattanzi, M. G. (2017). "Evidence for orbital motion of CW Leonis from ground-based astrometry". Monthly Notices of the Royal Astronomical Society: Letters. 471 (1): L1–L5. arXiv: 1706.04391 . Bibcode:2017MNRAS.471L...1S. doi: 10.1093/mnrasl/slx082 . S2CID   119070871.
  7. 1 2 3 Schmidt, M. R.; He, J. H.; Szczerba, R.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Decin, L.; Justtanont, K.; Teyssier, D.; Menten, K. M.; Neufeld, D. A.; Olofsson, H.; Planesas, P.; Marston, A. P.; Sobolev, A. M.; De Koter, A.; Schöier, F. L. (2016). "Herschel/HIFI observations of the circumstellar ammonia lines in IRC+10216". Astronomy & Astrophysics. 592: A131. arXiv: 1606.01878 . Bibcode:2016A&A...592A.131S. doi:10.1051/0004-6361/201527290. PMC   5217166 . PMID   28065983.
  8. ↑ Bergeat, J.; Knapik, A.; Rutily, B. (2001). "The effective temperatures of carbon-rich stars". Astronomy and Astrophysics. 369: 178–209. Bibcode:2001A&A...369..178B. doi: 10.1051/0004-6361:20010106 .
  9. ↑ "V* CW Leo -- Variable Star of Mira Cet type". SIMBAD. Centre de Données astronomiques de Strasbourg . Retrieved 2011-05-09.
  10. ↑ Becklin, E. E.; et al. (December 1969). "The Unusual Infrared Object IRC+10216" (PDF). Astrophysical Journal. 158: L133. Bibcode:1969ApJ...158L.133B. doi:10.1086/180450.
  11. ↑ Palaversa, Lovro; Ivezić, Željko; Eyer, Laurent; Ruždjak, Domagoj; Sudar, Davor; Galin, Mario; Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana; Božić, Hrvoje; Loebman, Sarah; Sesar, Branimir; Rimoldini, Lorenzo; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Stuart, J. Scott; Becker, Andrew C.; Srdoč, Gregor; Wozniak, Przemyslaw; Oluseyi, Hakeem (October 2013). "Exploring the Variable Sky with LINEAR. III. Classification of Periodic Light Curves". The Astronomical Journal. 146 (4): 101. arXiv: 1308.0357 . Bibcode:2013AJ....146..101P. doi:10.1088/0004-6256/146/4/101. hdl: 1721.1/92739 . S2CID   31317836.
  12. 1 2 Ladjal, D.; et al. (July 2010). "Herschel PACS and SPIRE imaging of CW Leonis". Astronomy and Astrophysics. 518: L141. arXiv: 1005.1433 . Bibcode:2010A&A...518L.141L. doi:10.1051/0004-6361/201014658. S2CID   14279789.
  13. 1 2 De Beck, E.; et al. (January 10, 2012). "On the physical structure of IRC+10216". Astronomy & Astrophysics. 539: A108. arXiv: 1201.1850 . Bibcode:2012A&A...539A.108D. doi:10.1051/0004-6361/201117635. S2CID   56163906.
  14. 1 2 Kim, Hyosun; Lee, Ho-Gyu; Mauron, Nicolas; Chu, You-Hua (2015). "HST Images Reveal Dramatic Changes in the Core of IRC+10216". The Astrophysical Journal. 804 (1): L10. arXiv: 1412.0083 . Bibcode:2015ApJ...804L..10K. doi:10.1088/2041-8205/804/1/L10. S2CID   118558287.
  15. ↑ Lasker, Barry M.; et al. (August 2008). "The Second-Generation Guide Star Catalog: Description and Properties". The Astronomical Journal. 136 (2): 735–766. arXiv: 0807.2522 . Bibcode:2008AJ....136..735L. doi:10.1088/0004-6256/136/2/735. S2CID   17641056.
  16. ↑ Jayasinghe, T.; Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Pawlak, M.; Shields, J. V.; Pojmanski, G.; Otero, S.; Britt, C. A.; Will, D. (2018). "The ASAS-SN catalogue of variable stars I: The Serendipitous Survey". Monthly Notices of the Royal Astronomical Society. 477 (3): 3145. arXiv: 1803.01001 . Bibcode:2018MNRAS.477.3145J. doi: 10.1093/mnras/sty838 .
  17. 1 2 Sahai, Raghvendra; Chronopoulos, Christopher K. (March 2010). "The Astrosphere of the Asymptotic Giant Branch Star IRC+10216". The Astrophysical Journal Letters. 711 (2): L53–L56. arXiv: 1001.4997 . Bibcode:2010ApJ...711L..53S. doi:10.1088/2041-8205/711/2/L53. S2CID   118705396.
  18. ↑ Dinh-V-Trung, Jeremy; Lim (May 2008). "Molecular Shells in IRC+10216: Evidence for Nonisotropic and Episodic Mass-Loss Enhancement". The Astrophysical Journal. 678 (1): 303–308. arXiv: 0712.1714 . Bibcode:2008ApJ...678..303D. doi:10.1086/527669. S2CID   16389370.
  19. ↑ Ford, K. E. Saavik; Neufeld, David A.; Goldsmith, Paul F.; Melnick, Gary J. (2003). "Detection of OH toward the Extreme Carbon Star IRC +10216". The Astrophysical Journal. 589 (1): 430–438. arXiv: astro-ph/0302103 . Bibcode:2003ApJ...589..430F. doi:10.1086/374552. S2CID   16682238.
  20. ↑ Lombaert, R.; Decin, L.; Royer, P.; De Koter, A.; Cox, N. L. J.; González-Alfonso, E.; Neufeld, D.; De Ridder, J.; Agúndez, M.; Blommaert, J. A. D. L.; Khouri, T.; Groenewegen, M. A. T.; Kerschbaum, F.; Cernicharo, J.; Vandenbussche, B.; Waelkens, C. (2016). "Constraints on the H2O formation mechanism in the wind of carbon-rich AGB stars". Astronomy & Astrophysics. 588: A124. arXiv: 1601.07017 . Bibcode:2016A&A...588A.124L. doi:10.1051/0004-6361/201527049. S2CID   62787287.
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