Astronomy:CN Boötis

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Short description: Am star in the constellation Boötes
CN Boötis
Location of CN Boötis (circled), seen in an optical image of Arcturus (bright star at center).
Observation data
Equinox J2000.0]] (ICRS)
Constellation Boötes
Right ascension  14h 16m 04.13970s[1]
Declination +18° 54′ 42.4852″[1]
Apparent magnitude (V) 5.96[2]
Characteristics
Evolutionary stage main sequence[1]
Spectral type A8V[3]
U−B color index +0.05[4]
B−V color index +0.26[4]
Variable type δ Sct[5]
Astrometry
Radial velocity (Rv)4.69±0.18[1] km/s
Proper motion (μ) RA: 40.288[1] mas/yr
Dec.: -30.863[1] mas/yr
Parallax (π)21.6479 ± 0.0332[1] mas
Distance150.7 ± 0.2 ly
(46.19 ± 0.07 pc)
Details
CN Boötis
Mass1.552±0.122[6] M☉
Radius1.603±0.108[6] R☉
Luminosity6.80±0.197[6] L☉
Surface gravity (log g)4.38[7] cgs
Temperature7388[7] K
Rotational velocity (v sin i)82[7] km/s
Other designations
BD+19°2779, GC 19251, HD 124953, HR 5343, SAO 100949, PPM 130449, TYC 1472-1427-1, GSC 01472-01427, 2MASS J14160414+1854426[8]
Database references
SIMBADCN Boo

CN Boötis (HD 124953, HR 5343), or simply CN Boo, is a white-hued variable star in the northern constellation of Boötes. With an apparent magnitude of 5.957, it can be faintly seen from Earth by the naked eye, just south-southeast of the much brighter Arcturus. It is located at a distance of 150.7 light-years (46.2 parsecs) according to Gaia DR3 parallax measurements, and is receding at a radial velocity of 4.69±0.18 km/s. It is a member of the Ursa Major Stream,[9] a group of stars with similar velocities that all formed around 300 million years ago.[10]

It was given its variable star designation, CN Boötis, in 1981.[11] Prior to that it was usually referred to as HR 5343 or HD 124953 in the literature.

Stellar characteristics

CN Boo is a late A-type star with an effective temperature of 7,388 K (7,115 °C; 12,839 °F), and has been classified as either a main-sequence star (spectral type A8V[12]/A9V[13]) or a giant star (spectral type A8III[7][9]). A 2023 estimate places its radius at a modest 1.6 Template:Solar radii,[6] which seems to suggest the former.

Light curves for CN Boötis, plotted from TESS data.[14]

The star has been known to be an Am star since at least 1964,[4] when the Bright Star Catalogue classified it as such. It was first discovered to be a δ Scuti variable in 1979 by Costa et al., with a period of 0.04 days (58 minutes) and an amplitude of 0.03 mag. This went against the notion that main-sequence Am stars do not pulsate, something that was accepted as fact at the time, so the team considered the Am classification to be erroneous.[15] A more recent study, however, accepts CN Boo as a pulsating Am star, since it shows a metal abundance pattern archetypal of Am stars, and has a minimum rotation speed (82 km/s) that allows for diffusion processes that cause Am characteristics.[7]

In 1991, CN Boo was found to be a soft X-ray source,[9] meaning that the X-rays it emits are of lower energies, i.e., longer wavelengths. It radiates energy at a rate of 2×1028 erg/s in X-rays,[13] chiefly at an energy range of below 0.5 keV[9] (wavelength >2.48 nm).

Possible companion

The 1991 edition of the Bright Star Catalogue lists CN Boo as a potential spectroscopic binary.[16] A 2008 study, however, did not detect significant radial velocity variations or any signals of the companion star in the spectrum of CN Boo, meaning that if a secondary star exists, it likely has a flux below 5% that of the primary star.[7]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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. ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355. Bibcode: 2000A&A...355L..27H. 
  3. ↑ Gatewood, George (2008). "Astrometric Studies of Aldebaran, Arcturus, Vega, the Hyades, and Other Regions". The Astronomical Journal 136 (1): 452. doi:10.1088/0004-6256/136/1/452. Bibcode: 2008AJ....136..452G. 
  4. ↑ 4.0 4.1 4.2 Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HGMN and Am stars". Astronomy and Astrophysics 498 (3): 961. doi:10.1051/0004-6361/200810788. Bibcode: 2009A&A...498..961R. 
  5. ↑ Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. 
  6. ↑ 6.0 6.1 6.2 6.3 Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023-06-01). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O 2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal 165 (6): 267. doi:10.3847/1538-3881/acd1ec. ISSN 0004-6256.  Record for this source at VizieR.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Fossati, L.; Kolenberg, K.; Reegen, P.; Weiss, W. (2008). "Abundance analysis of seven δ Scuti stars". Astronomy & Astrophysics 485 (1): 257–265. doi:10.1051/0004-6361:200809541. ISSN 0004-6361.  This article incorporates text from this source, which is available under the CC BY 4.0 license.
  8. ↑ "CN Boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=CN+Boo. 
  9. ↑ 9.0 9.1 9.2 9.3 Ayres, Thomas R.; Fleming, Thomas A.; Schmitt, Juergen H. M. M. (1991). "Digging in the coronal graveyard - A ROSAT observation of the red giant Arcturus". The Astrophysical Journal 376: L45. doi:10.1086/186099. ISSN 0004-637X. 
  10. ↑ King, Jeremy R. et al. (April 2003). "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group". The Astronomical Journal 125 (4): 1980–2017. doi:10.1086/368241. Bibcode: 2003AJ....125.1980K. 
  11. ↑ Kholopov, P. N.; Samus, N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (February 1981). "65th Name-List of Variable Stars". Information Bulletin on Variable Stars 1921: 1-21. https://ibvs.konkoly.hu/pub/ibvs/1901/1921.pdf. Retrieved 5 December 2024. 
  12. ↑ Gatewood, George (2008-07-01). "Astrometric Studies of Aldebaran, Arcturus, Vega, the Hyades, and Other Regions". The Astronomical Journal 136 (1): 452–460. doi:10.1088/0004-6256/136/1/452. ISSN 0004-6256. 
  13. ↑ 13.0 13.1 Panzera, M. R.; Tagliaferri, G.; Pasinetti, L.; Antonello, E. (August 1999). "X-ray emission from A0-F6 spectral type stars". Astronomy & Astrophysics 348: 161–169. Bibcode: 1999A&A...348..161P. 
  14. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  15. ↑ Costa, V.; Garrido, R.; Saez, M. (13 April 1979). "HR 5343 A New Delta Scuti Type Variable". Information Bulletin on Variable Stars (1584). Bibcode: 1979IBVS.1584....1C. 
  16. ↑ Hoffleit, Dorrit; Jaschek, Carlos (1991). The Bright Star Catalogue. Yale University Observatory. Bibcode: 1991bsc..book.....H. 



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