HD 4778 information

HD 4778
	; A light curve for GO Andromedae, plotted from TESS data
Observation data; Epoch J2000 Equinox J2000
Constellation	Andromeda
Right ascension	00h 50m 18.26563s
Declination	+45° 00′ 08.1439″
Apparent magnitude (V)	6.13
Characteristics
Spectral type	A3VpSiSrCrEuKsn
B−V color index	0.043±0.004
Variable type	α2 CVn
Astrometry
Radial velocity (Rv)	1.60 km/s
Proper motion (μ)	RA: 65.353 mas/yr ; Dec.: 4.133 mas/yr
Parallax (π)	9.3224 ± 0.0916 mas
Distance	350 ± 3 ly ; (107 ± 1 pc)
Absolute magnitude (MV)	1.18
Details
Mass	2.24±0.09 M☉
Radius	2.36±0.12 R☉
Luminosity	34.9±4.3 L☉
Surface gravity (log g)	4.12±0.09 cgs
Temperature	9,135±400 K
Rotation	2.5616 days
Rotational velocity (v sin i)	33 km/s
Age	77 Myr
Other designations
	GO Andromedae, BD+44° 176, FK5 2055, HD 4778, HIP 3919, HR 234, SAO 36702, PPM 43369
Database references
SIMBAD	data

HD 4778, also known as HR 234 and GO Andromedae, is a variable star in the constellation Andromeda. Its magnitude varies by 0.04 magnitudes from the median of 6.12 with a period of approximately 2.55 days.^[11] The star is located 350 light years away, as determined from its annual parallax shift of 9.32 mas.^[2]

This is an Ap star with a stellar classification of A3VpSiSrCrEuKsn,^[4] showing chemical peculiarities in its spectrum from strontium, chromium, and europium.^[12] It is an Alpha² Canum Venaticorum variable^[5] with a magnetic field that varies across the range +1,400 to −1,100 G.^[13] This rotation-modulated variability allows direct determination of the rotation rate of 2.5616 days.^[7]

HD 4778 has 2.24^[7] times the mass of the Sun and 2.36^[8] times the Sun's radius. The star is radiating 35^[8] times the Sun's luminosity from its photosphere at an effective temperature of 9,375 K.^[7] It is about 77^[9] million years old.

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Observation data Epoch J2000 Equinox J2000
A light curve for GO Andromedae, plotted from TESS data^[1]
Constellation	Andromeda
Right ascension	00^h 50^m 18.26563^s^[2]
Declination	+45° 00′ 08.1439″^[2]
Apparent magnitude (V)	6.13^[3]
Characteristics
Spectral type	A3VpSiSrCrEuKsn^[4]
B−V color index	0.043±0.004^[3]
Variable type	α² CVn^[5]
Astrometry

Radial velocity (R_v)	1.60^[6] km/s
Proper motion (μ)	RA: 65.353^[2] mas/yr Dec.: 4.133^[2] mas/yr
Parallax (π)	9.3224 ± 0.0916 mas^[2]
Distance	350 ± 3 ly (107 ± 1 pc)
Absolute magnitude (M_V)	1.18^[7]

Details

Mass	2.24±0.09^[7] `M`_☉
Radius	2.36±0.12^[8] `R`_☉
Luminosity	34.9±4.3^[8] `L`_☉
Surface gravity (log g)	4.12±0.09^[7] cgs
Temperature	9,135±400^[8] K
Rotation	2.5616^[7] days
Rotational velocity (v sin i)	33^[4] km/s
Age	77^[9] Myr

Other designations
GO Andromedae, BD+44° 176, FK5 2055, HD 4778, HIP 3919, HR 234, SAO 36702, PPM 43369^[10]
Database references
SIMBAD	data

HD 4778 information

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HD 4778

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