Phi Phoenicis

Phi Phoenicis
Observation data; ICRS)
Constellation	Phoenix
Right ascension	01h 54m 22.032s
Declination	−42° 29′ 48.94″
Apparent magnitude (V)	5.115
Characteristics
Spectral type	B9pHgMn; B9V
U−B color index	−0.125
B−V color index	−0.06
Distance	320 ± 6 ly ; (98 ± 2 pc)
Absolute magnitude (MV)	0.243±0.076
Semi-amplitude (K1); (primary)	9.21±0.09 km/s
Details
φ Phe A
	Myr
φ Phe B
Mass	0.91±0.025 M☉
HR 558, SAO 215697
Database references
SIMBAD	data

Phi Phoenicis,

light years from the Sun. It is moving away with a heliocentric radial velocity of 10.4 km/s.^[5]

Primary star

The primary component is a

Sun's luminosity from its photosphere at an effective temperature of about 10,500 K.^[6]

The reconstruction of the surface of Phi Phoenicis by Doppler imaging showed it to be heterogeneous with regions of different elemental abundances. In particular, the star forms spots with high or low abundances of yttrium, strontium, titanium, and chromium. The comparison of the abundance maps in different epochs revealed that the spot configurations vary on monthly or yearly time scales.^[8]^[5] The spectral lines of the irregularly distributed elements show variations that allowed a precise rotation period of 9.53 days to be determined, and also show evidence of long term abundance changes. The analysis of the spots suggests that the rotation axis is inclined to the line of sight by an angle of about 53°, and shows evidence of very weak differential rotation.^[5] The starspots probably cause milimagnitude variations in the brightness of Phi Phoenicis, even though there are no precise observations to confirm this.^[9]

The origin of the starspots and chemical anomalies in HgMn stars is uncertain and has generated controversy. Typically, such as for

Ap and Bp stars, inhomogeneously distributed elements are attributed to be large-scale organized magnetic fields, but there are not conclusive detection of magnetic fields in HgMn stars. In 2012, a study claimed to have detected a weak magnetic field in Phi Phoenicis correlated with the spots,^[4] but this has been contested.^[6]^[10] It is believed that diffusion processes in the atmosphere may be related to the chemical anomalies, but this does not explain quantitatively the observed variations.^[6]

Secondary star

Phi Phoenicis is a single-lined

spectroscopic binary with a period of 1126 days and an eccentricity of 0.59. There is no evidence for additional stars in the system, but in the past this has been considered a triple system, due to the detection of the wrong spectroscopic period.^[3]

The variability of the

inclination of the system and allowing to estimate the properties of the secondary star.^[3]

The orbit of the system is highly eccentricity and is seen almost side-on, with an inclination of 93 ± 4.7°. The high uncertainty means that the occurrence of

yellow dwarf with an effective temperature around 5,500 K, and is 5.7 visual magnitudes fainter than the primary. The average separation between the two star is estimated at around 3.4 AU.^[3]