HD 42818

HD 42818
Observation data
Epoch J2000      Equinox J2000
Constellation Camelopardalis
Right ascension 06h 18m 50.7809s[1]
Declination +69° 19′ 11.176″[1]
Apparent magnitude (V) +4.76[2]
Characteristics
Spectral type A0 Vn[3]
B−V color index 0.025±0.003
Astrometry
Radial velocity (Rv)−7.0±7.4[4] km/s
Proper motion (μ) RA: +0.686[1] mas/yr
Dec.: −108.270[1] mas/yr
Parallax (π)18.64 ± 0.23 mas[5]
Distance175 ± 2 ly
(53.6 ± 0.7 pc)
Absolute magnitude (MV)+1.11[2]
Details
HD 42818 A
Mass2.49[6] M☉
Radius2.7[7] R☉
Luminosity33.83[2] L☉
Surface gravity (log g)4.18±0.14[6] cgs
Temperature10,834±368[6] K
Metallicity [Fe/H]0.3[8] dex
Rotational velocity (v sin i)255[6] km/s
Age99[6] Myr
Other designations
BD+62°628, FK5 234, HD 42818, HIP 29997, HR 2209, SAO 13788[9]
Database references
SIMBADdata

HD 42818 is a suspected astrometric binary[10] star system in the northern circumpolar constellation of Camelopardalis. It is visible to the naked eye with an apparent visual magnitude of +4.76.[2] Based upon an annual parallax shift of 18.64±0.23 mas as seen from Earth's orbit,[5] it is located some 175 light years away. The system appears to be moving closer with a heliocentric radial velocity of −7 km/s.[4] As of 2012, it is estimated that the system will make its closest approach to the Sun in 485,000 years at a distance of around 169.2 ly (51.87 pc).[2]

The visible member, designated component A, is an A-type main-sequence star with a stellar classification of A0 Vn,[3] where the 'n' indicates "nebulous" absorption lines due to rotation. It is spinning rapidly with a projected rotational velocity of 255 km/s[6] (van Belle (2012) lists 325 km/s), giving the star a pronounced equatorial bulge.[11] Although spectral type A stars are not expected to emit X-rays, the coordinates of this star is a source of X-ray emission with a luminosity of 120.4×1020 W. This may be coming from a cooler, unseen companion.[12]

The primary has an estimated 2.49 times the mass of the Sun[6] and about 2.7 times the Sun's radius.[7] It is a relatively young star, about 99 million years old. The star is radiating 34 times the Sun's luminosity from its photosphere at an effective temperature of 10,834 K.[6]

  1. ^ a b c d Cite error: The named reference Gaia2016 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  6. ^ a b c d e f g h Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference cadars was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference gebran2016 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference vanBelle2012 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Schroeder2007 was invoked but never defined (see the help page).