HD 203842 information

HD 203842
	Location of HD 203842 (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Equuleus
Right ascension	21h 24m 24.56372s
Declination	+10° 10′ 27.1976″
Apparent magnitude (V)	6.32±0.01
Characteristics
Evolutionary stage	Hertzsprung gap
Spectral type	F5 III
U−B color index	+0.13
B−V color index	+0.47
Astrometry
Radial velocity (Rv)	−21.8±3.6 km/s
Proper motion (μ)	RA: +75.072 mas/yr ; Dec.: +20.436 mas/yr
Parallax (π)	8.7242 ± 0.1771 mas
Distance	374 ± 8 ly ; (115 ± 2 pc)
Absolute magnitude (MV)	+1.06
Details
Mass	2.00 M☉
Radius	4.54±0.23 R☉
Luminosity	31.1±1.2 L☉
Surface gravity (log g)	3.47 cgs
Temperature	6,271±42 K
Metallicity [Fe/H]	+0.19+0.04; −0.05 dex
Rotational velocity (v sin i)	80.6 km/s
Age	1.24 Gyr
Other designations
	30 G. Equulei[14], AG+09°2981, BD+09°4800, GC 29969, HD 203842, HIP 105695, HR 8191, SAO 126774
Database references
SIMBAD	data

HD 203842, also known as HR 8191 or rarely 30 G. Equueli, is a solitary, yellowish-white hued star located in the constellation Equuleus. It has an apparent magnitude of 6.32, placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 374 light years,^[1] and it is currently drifting closer with a somewhat constrained heliocentric radial velocity of −21.8 km/s.^[6] At its current distance HD 203842's brightness is diminished by 0.15 magnitudes due to interstellar dust^[16] and it has an absolute magnitude of +1.06.^[7]

A 2005 Hipparcos survey noticed variations in its proper motion, which would indicate that it is an astrometric binary.^[17] However, a subsequent survey revealed that HD 203842 is not an astrometric binary (32% chance) and is more likely to be solitary.^[18] This object is part of the Hyades Stream.^[19]

HD 203842 has a stellar classification of F5 III,^[4] indicating that it is an evolved F-type giant star. It is currently in the Hertzsprung gap, meaning that it exhausting its supply of hydrogen and evolving towards the red giant branch. It has double times the Sun's mass but at the age of 1.24 billion years,^[8] it has expanded to 4.54 times the Sun's radius.^[9] It radiates 31.1 times the Sun's luminosity^[1] from its enlarged photosphere at an effective temperature of 6,271 K.^[11] HD 203842 is metal enriched with 155% the Sun's iron abundance^[12] and spins quickly with a projected rotational velocity of 80.6 km/s.^[13]

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[Tycho2000-2] Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).

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[Roman1955-4] Cite error: The named reference Roman1955 was invoked but never defined (see the help page).

[Johnson1966-5] Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).

[Gontcharov2006-6] Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).

[Anderson2012-7] Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).

[Dermarque2004-8] Cite error: The named reference Dermarque2004 was invoked but never defined (see the help page).

[Kervella2004-9] Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).

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[Luck2015-11] Cite error: The named reference Luck2015 was invoked but never defined (see the help page).

[Bochanski2018-12] Cite error: The named reference Bochanski2018 was invoked but never defined (see the help page).

[Solano1997-13] Cite error: The named reference Solano1997 was invoked but never defined (see the help page).

[Gould1879-14] Cite error: The named reference Gould1879 was invoked but never defined (see the help page).

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[Gontcharov2017-16] Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).

[Makarov2005-17] Cite error: The named reference Makarov2005 was invoked but never defined (see the help page).

[Frankowski2006-18] Cite error: The named reference Frankowski2006 was invoked but never defined (see the help page).

[Montes2001-19] Cite error: The named reference Montes2001 was invoked but never defined (see the help page).

Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Location of HD 203842 (circled)
Constellation	Equuleus
Right ascension	21^h 24^m 24.56372^s^[1]
Declination	+10° 10′ 27.1976″^[1]
Apparent magnitude (V)	6.32±0.01^[2]
Characteristics
Evolutionary stage	Hertzsprung gap^[3]
Spectral type	F5 III^[4]
U−B color index	+0.13^[5]
B−V color index	+0.47^[5]
Astrometry

Radial velocity (R_v)	−21.8±3.6^[6] km/s
Proper motion (μ)	RA: +75.072 mas/yr^[1] Dec.: +20.436 mas/yr^[1]
Parallax (π)	8.7242 ± 0.1771 mas^[1]
Distance	374 ± 8 ly (115 ± 2 pc)
Absolute magnitude (M_V)	+1.06^[7]

Details

Mass	2.00^[8] `M`_☉
Radius	4.54±0.23^[9] `R`_☉
Luminosity	31.1±1.2^[1] `L`_☉
Surface gravity (log g)	3.47^[10] cgs
Temperature	6,271±42^[11] K
Metallicity [Fe/H]	+0.19^+0.04 _−0.05^[12] dex
Rotational velocity (v sin i)	80.6^[13] km/s
Age	1.24^[8] Gyr

Other designations
30 G. Equulei[14], AG+09°2981, BD+09°4800, GC 29969, HD 203842, HIP 105695, HR 8191, SAO 126774^[15]
Database references
SIMBAD	data

HD 203842 information

and 2 Related for: HD 203842 information

HD 203842

List of stars in Equuleus