N Scorpii

N Scorpii, also known as HD 148703, is a solitary,^[14] bluish-white hued star located in the southern constellation Scorpius. It has an apparent magnitude of 4.23, making it readily visible to the naked eye. N Scorpii was initially given the Bayer designation Alpha Normae by Lacaille but it was later moved from Norma to Scorpius.^[15] N Scorpii is currently located 550 light years away based on parallax measurements from the Hipparcos satellite and is part of the Upper Scorpius–Centaurus region of the Scorpius–Centaurus association.^[16]

N Scorpii

Location of N Scorpii on the map
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Scorpius
Right ascension	16h 31m 22.93300s[1]
Declination	−34° 42′ 15.7146″[1]
Apparent magnitude (V)	4.23[2]
Characteristics
Spectral type	B2 III-IV[3]
U−B color index	−0.76[2]
B−V color index	−0.17[2]
Variable type	candidate β Cephei[4]
Astrometry
Radial velocity (Rv)	0.8±1.5[5] km/s
Proper motion (μ)	RA: −12.05±0.20 mas/yr[1] Dec.: −18.16±0.13 mas/yr[1]
Parallax (π)	5.88±0.19 mas[1]
Distance	550 ± 20 ly (170 ± 5 pc)
Absolute magnitude (MV)	−1.91[6]
Details
Mass	7.8±0.1[7] M☉
Radius	6.25[8] R☉
Luminosity (bolometric)	6,918[9] L☉
Surface gravity (log g)	4.0[9] cgs
Temperature	21,877[9] K
Metallicity [Fe/H]	+0.01[10] dex
Rotational velocity (v sin i)	70±8[11] km/s
Age	22±4[7] Myr
Other designations
N Scorpii, 72 G. Scorpii[12], CD−34°11044, CPD−34°6528, FK5 1431, GC 22195, HD 148703, HIP 80911, HR 6143, SAO 207732[13]
Database references
SIMBAD	data

N Scorpii has been given several stellar classifications over the years. It has been given the luminosity class of a main sequence star (V),^[17] a subgiant (IV),^[18] an evolved giant star (III),^[19] or a blend between the last two classes (III-IV).^[3] It is generally classified as either a B2 or B3 star several times hotter than the Sun. HD 148703 is a candidate β Cephei variable^[4] and its variability was first noticed in 1983 by C. Sterken.^[20] Further observations were made by Abt et al. (2002) by observing its projected rotational velocity.^[21] It was identified as a candidate in 2002 in a survey for non-radial pulsations in B-type stars.^[22]

The object has two generally accepted classes: B2 III-IV and B2 IV. It has 7.8 times the mass of the Sun^[7] and 6.25 times its size.^[8] It has a bolometric luminosity 6,918 times greater than the Sun from its photosphere at an effective temperature of 21,877 K.^[9] N Scorpii is estimated to be 22 million years old,^[7] which is twice the average age of the aforementioned association. Like most hot stars, N Scorpii spins rapidly, having a projected rotational velocity of 70 km/s.^[11]