Astronomy:T Monocerotis

From HandWiki
Short description: Cepheid Variable in constellation of Monoceros
T Monocerotis
Location of T Monocerotis (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Monoceros
Right ascension  06h 25m 13.00s[1]
Declination +07° 05′ 08.6″[1]
Apparent magnitude (V) 5.58–6.58[2]
Characteristics
Evolutionary stage Supergiant + Main-sequence
Spectral type G3Iabv + A0p[3]
Variable type δ Cep[2]
Astrometry
Radial velocity (Rv)+48.8±9.1[1] km/s
Proper motion (μ) RA: +0.846[1] mas/yr
Dec.: −3.025[1] mas/yr
Parallax (π)0.533 ± 0.066[1] mas
Distanceapprox. 6,100 ly
(approx. 1,900 pc)
Other designations
T Mon, BD+07 1273, HD 44990, HIP 30541, HR 2310, SAO 113845, TYC 145-875-1, IRAS 06225+0706, 2MASS J06251300+0705084[4]
Database references
SIMBADdata

T Monocerotis (T Mon) is a classical Cepheid variable star in the constellation of Monoceros, visually located 2° northwest of Epsilon Monocerotis. Along with Eta Aquilae and X Sagittarii, it is one of the Cepheid variables considered easy to find in the night sky.[5] It is located 1350 parsecs or 4400 light-years from the solar system.[6] The brightness of T Monocerotis varies between apparent magnitude +5.58 and +6.62 over a period of 27.0247 days.[7] This period has been increasing over time, being 27.0092 days before the year 1900.[8]

Charecterstics and observation

T Monocerotis is a classic Cepheid variable, a class of young pulsating Population I stars, usually supergiants with a luminosity and size considerably greater than the Sun. The effective temperature of T Monocerotis is approximately 5200K[6] and its luminosity is 4985 times greater than solar luminosity.[9] Its average radius is 131 times larger than that of the Sun,[10] equivalent to 0.61 AU. However, due to the pulsations it experiences, the difference between its maximum and minimum radius is equal to 33 times the solar radius.[11] It has a mass approximately seven times greater than the mass of the sun.[9] It has a higher metallic content than the Sun ([Fe/H] = +0.23). All the elements evaluated, with the exception of manganese, are "overabundant" in relation to solar levels, with lanthanum standing out in this regard, its relative abundance being 3.5 times greater.[6]

Mid-infrared interferometry with the Very Large Telescope Interferometer (VLTI/MIDI) in 2013 revealed an extended molecular envelope around T Monocerotis, extending to about 40 stellar radii at 8.6 μm. This envelope, likely composed of dust and gas ejected during the star's evolution, is asymmetric and shows evidence of mass loss, consistent with other Galactic Cepheids.[12]

Companion

T Monocerotis is a single-lined spectroscopic binary with a hot companion detected via ultraviolet spectroscopy with the International Ultraviolet Explorer (IUE) in 1980. The companion, likely a A-type main-sequence star, contributes significantly to the system's UV flux, showing absorption lines from highly ionized in C IV and Si IV. The orbital period aligns with the Cepheid's pulsation period (∼27 days), complicating velocity measurements, but preliminary orbital elements suggest an eccentricity of ∼0.5 and a semi-amplitude K ≈ 20 km/s for the primary. Historical radial velocity data from over 80 years support the binary hypothesis.[13][14][15]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 "T Mon". AAVSO. https://vsx.aavso.org/index.php?view=detail.top&oid=18831. 
  3. ↑ Remage Evans, Nancy et al. (2013). "Binary Cepheids: Separations and Mass Ratios in 5 M ⊙ Binaries". The Astronomical Journal 146 (4): 93. doi:10.1088/0004-6256/146/4/93. Bibcode: 2013AJ....146...93E. 
  4. ↑ "T Monocerotis". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=T+Monocerotis. 
  5. ↑ Estrellas masivas y cómo medir sus propiedades por Pablo Lonnie Pacheco (astronomos.org) 29 de septiembre de 2008, visitado el 20 de julio de 2011.
  6. ↑ 6.0 6.1 6.2 Luck, R. Earle; Lambert, David L. (2011). "The Distribution of the Elements in the Galactic Disk. III. A Reconsideration of Cepheids from l = 30° to 250°". The Astronomical Journal 142 (4). id. 136. http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1108.1947. 
  7. ↑ T Monocerotis (General Catalogue of Variable Stars)
  8. ↑ "T Monocerotis (Alcyone)". http://www.alcyone-software.com/SIT/cepheides/SIT003051.htm. 
  9. ↑ 9.0 9.1 Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten 331 (4): 349. doi:10.1002/asna.200911355. p. 349. Bibcode: 2010AN....331..349H. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2010AN....331..349H&db_key=AST&nosetcookie=1. 
  10. ↑ Neilson, Hilding R.; Lester, John B. (2008). "On the Enhancement of Mass Loss in Cepheids Due to Radial Pulsation". The Astrophysical Journal 684 (1): 569. doi:10.1086/588650. pp. 569-587. Bibcode: 2008ApJ...684..569N. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2008ApJ...684..569N&db_key=AST&nosetcookie=1. 
  11. ↑ Moskalik, P.; Gorynya, N. A. (2005). "Mean Angular Diameters and Angular Diameter Amplitudes of Bright Cepheids". Acta Astronomica 55: 247. pp. 247-260. Bibcode: 2005AcA....55..247M. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?2005AcA....55..247M&db_key=AST. 
  12. ↑ Gallenne, A.; Mérand, A.; Kervella, P.; Chesneau, O.; Breitfelder, J.; Gieren, W. (2013-10-01). "Extended envelopes around Galactic Cepheids - IV. T Monocerotis and X Sagittarii from mid-infrared interferometry with VLTI/MIDI" (in en). Astronomy & Astrophysics 558: A140. doi:10.1051/0004-6361/201322257. ISSN 0004-6361. Bibcode: 2013A&A...558A.140G. https://www.aanda.org/articles/aa/abs/2013/10/aa22257-13/aa22257-13.html. 
  13. ↑ Mariska, J. T.; Doschek, G. A.; Feldman, U. (1981-01-01). "The detection of companion stars to the Cepheid variables ETA Aquilae and T Monocerotis" (in en). NASA. Goddard Space Flight Center the Universe at Ultraviolet Wavelengths: The First Two Yrs. Of Intern. Ultraviolet Explorer. https://ntrs.nasa.gov/citations/19810017383. 
  14. ↑ Evans, Nancy Remage; Carpenter, Kenneth; Robinson, Richard; Massa, Derck; Wahlgren, Glenn M.; Vinko, Jozsef; Szabados, Laszlo (1999-10-10). "Toward an Orbit for the High-Luminosity Cepheid T Monocerotis" (in en). The Astrophysical Journal 524 (1): 379–393. doi:10.1086/307810. ISSN 0004-637X. Bibcode: 1999ApJ...524..379E. https://iopscience.iop.org/article/10.1086/307810. 
  15. ↑ Coulson, Iain M. (August 1983). "The binary nature of the Cepheid T Monocerotis" (in en). Monthly Notices of the Royal Astronomical Society 203 (4): 925–933. doi:10.1093/mnras/203.4.925. ISSN 0035-8711. 



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:T_Monocerotis&oldid=4216375"