QQ Telescopii

QQ Telescopii, also known as HD 185139 or simply QQ Tel, is a solitary variable star located in the southern constellation Telescopium. It has an apparent magnitude of 6.25,^[2] placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 333 light years^[1] and it is currently receding with a heliocentric radial velocity of 7.8 km/s.^[6] At its current distance, QQ Telescopii's brightness is diminished by two tenths of a magnitude due to interstellar dust^[16] and it has an absolute magnitude of +1.01.^[7]

A light curve for QQ Telescopii, plotted from TESS data^[17]

QQ Telescopii

Location of QQ Telescopii (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Telescopium
Right ascension	19h 39m 41.77938s[1]
Declination	−45° 16′ 42.7871″[1]
Apparent magnitude (V)	6.25[2]
Characteristics
Spectral type	F2 IV[3] or F0 III:[4]
B−V color index	+0.28[2]
Variable type	δ Scuti[5]
Astrometry
Radial velocity (Rv)	7.8±1.5[6] km/s
Proper motion (μ)	RA: −22.160 mas/yr[1] Dec.: +5.375 mas/yr[1]
Parallax (π)	9.8017±0.0327 mas[1]
Distance	333 ± 1 ly (102.0 ± 0.3 pc)
Absolute magnitude (MV)	+1.01[7]
Details
Mass	1.68[8] M☉
Radius	3.19±0.16[9] R☉
Luminosity	26.1±0.2[1] L☉
Surface gravity (log g)	3.73±0.12[10] cgs
Temperature	7,380±136[11] K
Metallicity [Fe/H]	+0.07±0.15[12] dex
Rotational velocity (v sin i)	45±5[13] km/s
Age	995+121 −120[1] Myr
Other designations
66 G. Telescopii[14], QQ Tel, CD−45°13354, CPD−45°9764, GC 27167, HD 185139, HIP 96721, HR 7461, SAO 229800[15]
Database references
SIMBAD	data

HD 185139 was discovered to be a δ Scuti variable in 1982 by Debora W. Kurtz along with HR 151 (BG Ceti).^[18] After a few years of subsequent observations, it was given the variable designation QQ Telescopii in 1985.^[19] In 2002, C. Koen and colleagues attempted to identify the pulsation modes of the star.^[13] The brightness of QQ Tel fluctuates by about 0.05 magnitudes in the blue passband within 1.56 hours.^[5]

QQ Telescopii has a stellar classification of F2 IV,^[3] indicating that it is a slightly evolved F-type subgiant. It was previously classified as kA6mF0 III^[20] and A0pSr(CrSi),^[21] indicating that it is either a chemically peculiar Ap star or Am star. However, Renson & Manfroid (2009) considers its chemical peculiarity to be doubtful.^[22] Andersen & Nordstöm (1978) give it a class of F0 III:,^[4] indicating that it is an evolved F-type giant star with uncertainty about the luminosity class. Evolutionary models place it very close to the end of its main sequence life.^[1]

With 1.68 times the mass of the Sun^[8] and an enlarged radius 3.19 times that of the Sun,^[9] QQ Telescopii radiates 26.1 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 7,380 K,^[11] giving it a yellowish-white hue. It is slightly metal enriched at [Fe/H] = +0.07^[12] but the value is poorly constrained. The star is estimated to be 995 million years old^[1] and it spins modestly with a projected rotational velocity of 45 km/s.^[13]