CN Boötis

CN Boötis
Location of CN Boötis (circled), seen in an optical image of Arcturus (bright star at center).
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 16m 04.13970s[1]
Declination +18° 54′ 42.4852″[1]
Apparent magnitude (V) 5.957[2]
Characteristics
Spectral type A8V[2]
B−V color index +0.274[2]
Variable type Delta Scuti variable
Astrometry
Radial velocity (Rv)4.69±0.18[3] km/s
Proper motion (μ) RA: 40.288[1] mas/yr
Dec.: -30.863[1] mas/yr
Parallax (π)21.6479 ± 0.0332 mas[1]
Distance150.7 ± 0.2 ly
(46.19 ± 0.07 pc)
Details
CN Boötis
Mass1.552±0.122[4] M☉
Radius1.603±0.108[4] R☉
Luminosity6.80±0.197[4] L☉
Surface gravity (log g)4.38[5] cgs
Temperature7388[5] K
Rotational velocity (v sin i)82[5] km/s
Other designations
AG+19° 1338, BD+19° 2779, Gaia DR3 1233902704963092608, GC 19251, HD 124953, HR 5343, SAO 100949, PPM 130449, TIC 135169898, TYC 1472-1427-1, GSC 01472-01427, 2MASS J14160414+1854426[2]
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-southwest of the much brighter Arcturus. It is located at a distance of 150.7 light-years (46.2 parsecs) according to Gaia EDR3 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,[6] a group of stars with similar velocities that all formed around 300 million years ago.[7]

It was given its variable star designation, CN Boötis, in 1981.[8] 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[9]/A9V[10]) or a giant star (spectral type A8III[5][6]). A 2023 estimate places its radius at a modest 1.6 R☉,[4] which seems to suggest the former.

Light curves for CN Boötis, plotted from TESS data.[11]

The star was known to be an Am star since at least 1964, 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.[12] 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.[5] In 1991, CN Boo was found to be a soft X-ray source,[6] meaning that the X-rays it emits are of lower energies, i.e., longer wavelengths. It radiates energy at a rate of 2×1028 ergs per second in X-rays,[10] chiefly at an energy range of below 0.5 keV[6] (wavelength >2.48 nm).

Possible companion

The 1991 edition of the Bright Star Catalogue lists CN Boo as a potential spectroscopic binary.[13] 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.[5]

References

  1. ^ a b c d e 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. ^ a b c d "CN Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 22 September 2024.
  3. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. ^ a b c d Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (1 June 2023). "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. arXiv:2304.12490. doi:10.3847/1538-3881/acd1ec. ISSN 0004-6256. Record for this source at VizieR.
  5. ^ a b c d e f Fossati, L.; Kolenberg, K.; Reegen, P.; Weiss, W. (2008). "Abundance analysis of seven δ Scuti stars". Astronomy & Astrophysics. 485 (1): 257–265. arXiv:0804.2402. 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.
  6. ^ a b c d 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.
  7. ^ 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. Bibcode:2003AJ....125.1980K. doi:10.1086/368241.
  8. ^ Kholopov, P. N.; Samus, N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (February 1981). "65th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 1921: 1–21. Retrieved 5 December 2024.
  9. ^ Gatewood, George (1 July 2008). "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.
  10. ^ a b 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. arXiv:astro-ph/9906221. Bibcode:1999A&A...348..161P.
  11. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 2 October 2024.
  12. ^ 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.
  13. ^ Hoffleit, Dorrit; Jaschek, Carlos (1991). The Bright Star Catalogue. Yale University Observatory. Bibcode:1991bsc..book.....H.