HD 178845

HD 178845
Location of HD 178845 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Telescopium
A
Right ascension 19h 12m 46.13847s[1]
Declination −50° 29′ 11.1095″[1]
Apparent magnitude (V) 6.13[2]
B
Right ascension 19h 12m 45.51968s[3]
Declination −50° 29′ 08.7448″[3]
Apparent magnitude (V) 10.90±0.02[4]
Characteristics
A
Spectral type G8 III[5]
B−V color index +0.95[2]
Astrometry
A
Radial velocity (Rv)−26.4±0.4[6] km/s
Proper motion (μ) RA: +44.868 mas/yr[1]
Dec.: −42.034 mas/yr[1]
Parallax (π)8.6125 ± 0.0283 mas[1]
Distance379 ± 1 ly
(116.1 ± 0.4 pc)
Absolute magnitude (MV)+0.68[7]
B
Radial velocity (Rv)−24.2±5.3[8] km/s
Proper motion (μ) RA: +46.984 mas/yr[3]
Dec.: −41.403 mas/yr[3]
Parallax (π)8.6162 ± 0.024 mas[3]
Distance379 ± 1 ly
(116.1 ± 0.3 pc)
Details[9]
A
Mass2.35±0.08 M☉
Radius9.13±0.16 R☉
Luminosity47±0.9 L☉
Surface gravity (log g)2.95±0.10 cgs
Temperature5,001±36 K
Metallicity [Fe/H]+0.02±0.03 dex
Rotational velocity (v sin i)2.6±1.1[10] km/s
Age455+45
−46[1] Myr
Other designations
49 G. Telescopii[11], CD−50°12377, CPD−50°10995, HD 178845, HIP 94398, HR 7271, SAO 245976, CCDM J19128-5029AB, WDS J19128-5029A
Database references
SIMBADdata

HD 178845, also known as HR 7271 or rarely 49 G. Telescopii, is a binary star located in the southern constellation Telescopium. Gaia DR3 parallax measurements place the system 379 light years away[3][1] and both components are approaching the Solar System with heliocentric radial velocities of −26 km/s and −24 km/s respectively.[6][8] At its current distance, HD 178845A's brightness is diminished by 0.22 magnitudes due to interstellar dust.[12]

The primary has an apparent magnitude of 6.13,[2] placing it near the naked eye viewing limit and the companion has an apparent magnitude of 10.9,[4] making it readily visible in medium-sized telescopes. The system was first observed by astronomer Willem Hendrik van den Bos in 1930.[13] As of 1991, HD 178845B is located 7.2" away along a position angle of 320°.[14]

The primary is an evolved red giant with a stellar classification of G8 III.[5] It has 2.35 times the mass of the Sun[9] but at the age of 455 million years,[1] it has expanded to 9.1 times its radius.[9] It radiates 47 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,001 K,[9] giving it a yellow hue. It has a solar metallicity ([Fe/H] = +0.02[9]) and spins modestly with a projected rotational velocity of 2.6 km/s.[10]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR3A was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference GaiaDR3B was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Houk1978 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  9. ^ a b c d e Cite error: The named reference Ottoni2022 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference De Medeiros2014 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference vandenBos1930 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Mason2001 was invoked but never defined (see the help page).