HD 194783

Last updated
HD 194783
Microscopium constellation map.svg
Red circle.svg
Location of HD 194783 on the map (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Microscopium
Right ascension 20h 28m 46.74360s [1]
Declination −35° 35′ 45.1068″ [1]
Apparent magnitude  (V)6.08±0.01 [2]
Characteristics
Spectral type B8 II/III [3] or B9pHgMn [4]
B−V color index −0.11 [5]
Astrometry
Radial velocity (Rv)−9.7±1.2 [6] km/s
Proper motion (μ)RA: +2.959 mas/yr [1]
Dec.: −21.638 mas/yr [1]
Parallax (π)4.3936±0.0714  mas [1]
Distance 740 ± 10  ly
(228 ± 4  pc)
Absolute magnitude  (MV)−0.59 [7] or −1.10 [8]
Details
Mass 4.03±0.05 [1]   M☉
Radius 4.19±0.21 [9]   R☉
Luminosity 390±12 [1]   L☉
Surface gravity (log g)3.75 [10]   cgs
Temperature 14,028 [8]   K
Metallicity [Fe/H]−0.20 [10]   dex
Rotation 6  d [11]
Rotational velocity (v sin i)≤30 [11]  km/s
Age 70 [8]   Myr
Other designations
2 G. Microscopii [12] , CD−36°14166, CPD−36°9170, FK5 3637, GC 28464, HD 194783, HIP 101017, HR 7817, SAO 212160, TIC 34864575 [13]
Database references
SIMBAD data

HD 194783 (HR 7817; 2 G. Microscopii) is a solitary star located in the southern constellation of Microscopium near the border with Sagittarius. It is barely visible to the naked eye as a bluish-white-hued point of light with an apparent magnitude of 6.08. [2] The object is located relatively far at a distance of 740 light-years based on Gaia DR3 parallax measurements, [1] but it is drifting closer with a heliocentric radial velocity of −9.7  km/s . [6] At its current distance, HD 194783's brightness is diminished by an interstellar extinction of 0.31 magnitudes [14] and it has an absolute magnitude of either −0.59 or −1.10, [7] [8] depending on the source.

HD 194783 has a stellar classification of B8 II/III, [3] indicating that it is an evolved B-type star with the blended luminosity class of a bright giant and a lower luminosity giant star. It has also been given a class of B9pHgMn, [4] indicating that it is a chemically peculiar mercury-manganese star. It has 4.03 times the mass of the Sun [1] and a slightly enlarged radius 4.19 times that of the Sun's. [9] It radiates 390 times the luminosity of the Sun [1] from its photosphere at an effective temperature of 14,028  K . [8] The heavy metal (iron) to hydrogen ratio–what astronomers dub as the star's metallicity–is 63% that of the Sun's. [10] HD 194783 is estimated to be approximately 70 million years old. [8]

In 1989, HD 194783 was reported to be a spectrum variable with a period of 6 days. The projected rotational velocity of the star is not known, but it is said to be no higher than 30  km/s . [11] HD 194783 was also observed to have a relatively weak magnetic field of about −43 gauss. [15]

References

  1. 1 2 3 4 5 6 7 8 9 10 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.
  2. 1 2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27 –L30. Bibcode:2000A&A...355L..27H. ISSN   0004-6361. S2CID   17128864.
  3. 1 2 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. Vol. 3. Bibcode:1982mcts.book.....H.
  4. 1 2 Andersen, J.; Nordstrom, B. (September 1977). "Bright southern stars of astrophysical interest". Astronomy and Astrophysics Supplement Series. 29: 309–312. Bibcode:1977A&AS...29..309A. ISSN   0365-0138.
  5. ↑ Corben, P. M. (April 1971). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of South Africa. 30 (4): 37. Bibcode:1971MNSSA..30...37C. ISSN   0024-8266.
  6. 1 2 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053 . Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN   1562-6873. ISSN   1063-7737. S2CID   119231169.
  7. 1 2 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971 . Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN   1562-6873. ISSN   1063-7737. S2CID   119257644.
  8. 1 2 3 4 5 6 Westin, T. N. G. (April 1985). "The local system of early type stars. Spatial extent and kinematics". Astronomy and Astrophysics Supplement Series. 60: 99–134. Bibcode:1985A&AS...60...99W. ISSN   0365-0138. S2CID   119020376.
  9. 1 2 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics. 426 (1): 297–307. arXiv: astro-ph/0404180 . Bibcode:2004A&A...426..297K. doi: 10.1051/0004-6361:20035930 . eISSN   1432-0746. ISSN   0004-6361. S2CID   6077801.
  10. 1 2 3 Anders, F.; et al. (February 2022). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5". Astronomy & Astrophysics. 658: A91. arXiv: 2111.01860 . Bibcode:2022A&A...658A..91A. doi: 10.1051/0004-6361/202142369 . eISSN   1432-0746. ISSN   0004-6361.
  11. 1 2 3 Rajamohan, R.; Paranjpye, A. (1989). "The Spectrum Variable HR 7817 = HD 194783". Information Bulletin on Variable Stars. 3284: 1. Bibcode:1989IBVS.3284....1R. ISSN   0374-0676.
  12. ↑ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
  13. ↑ "HD 194783". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved December 3, 2023.
  14. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv: 1709.01160 . Bibcode:2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219 . eISSN   1365-2966. ISSN   0035-8711. S2CID   118879856.
  15. ↑ Hubrig, S.; North, P.; Schöller, M.; Mathys, G. (2006). "Evolution of magnetic fields in stars across the upper main sequence: I. Catalogue of magnetic field measurements with FORS 1 at the VLT". Astronomische Nachrichten. 327 (4): 289–297. arXiv: astro-ph/0603610 . Bibcode:2006AN....327..289H. doi:10.1002/asna.200610535. ISSN   0004-6337. S2CID   16248930.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.