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Rho Hydrae

Not to be confused with R Hydrae.
Rho Hydrae
Location of ρ Hydrae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 08h 48m 25.97057s[1]
Declination +05° 50′ 16.1283″[1]
Apparent magnitude (V) 4.34[2]
Characteristics
Spectral type A0 Vn[3]
U−B color index −0.04[2]
B−V color index −0.04[2]
Astrometry
Radial velocity (Rv)+32.8[4] km/s
Proper motion (μ) RA: −17.33[1] mas/yr
Dec.: −29.41[1] mas/yr
Parallax (π)9.21±0.21 mas[1]
Distance354 ± 8 ly
(109 ± 2 pc)
Absolute magnitude (MV)−0.83[5]
Details[3]
Mass3.24±0.05 M☉
Radius2.0[6] R☉
Luminosity242 L☉
Temperature9,795 K
Rotational velocity (v sin i)128 km/s
Age350[7] Myr
Other designations
ρ Hya, 13 Hya, BD+06°2040, HD 75137, HIP 43234, HR 3492, SAO 117146[8]
Database references
SIMBADdata

Rho Hydrae, equally written ρ Hydrae, is a binary star[9] in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.34.[2] The distance to this system, based upon an annual parallax shift of 9.21 mas,[1] is about 354 light years. At that distance, the visual magnitude is diminished by an interstellar extinction of 0.06 magnitudes, due to intervening dust.[7]

The primary component is an A-type main sequence star with a stellar classification of A0 Vn.[3] It has around double[6] the radius of the Sun and 3.2 times the Sun's mass. Rho Hydrae is around 350 million years old[7] and has a high rate of spin, with a projected rotational velocity of 128 km/s. It radiates 242 times the solar luminosity from its outer atmosphere at an effective temperature of 9,795 K.[3] The companion is a magnitude 11.9 star at an angular separation of 12.1 arc seconds along a position angle of 146°, as of 2000.[10]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Zorec2012 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference PasinettiFracassini2001 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
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