Theta1 Microscopii

For other stars with the name θ Microscopii, see Theta Microscopii.
Theta1 Microscopii
Location of θ1 Microscopii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Microscopium
Right ascension 21h 20m 45.62633s[1]
Declination −40° 48′ 34.3607″[1]
Apparent magnitude (V) 4.82[2]
Characteristics
Spectral type A7VpSrCrEu[3]
U−B color index -0.07[2]
B−V color index +0.02[2]
Variable type α2 CVn[4]
Astrometry
Radial velocity (Rv)+2.30[5] km/s
Proper motion (μ) RA: +75.480[1] mas/yr
Dec.: +8.657[1] mas/yr
Parallax (π)18.2678 ± 0.5314 mas[1]
Distance179 ± 5 ly
(55 ± 2 pc)
Absolute magnitude (MV)1.03[6]
Details[7]
Mass2.32+0.18
−0.26 M☉
Radius2.35±0.34 R☉
Luminosity36.3+8.4
−6.8 L☉
Surface gravity (log g)4.06±0.12 cgs
Temperature9,240±480 K
Metallicity [Fe/H]0.00[8] dex
Rotational velocity (v sin i)43.7±1.7 km/s
Age437±209 Myr
Other designations
θ1 Mic, CD−41°14475, FK5 802, GC 29854, HD 203006, HIP 105382, HR 8151, SAO 230644, WDS J21208-4049[9]
Database references
SIMBADdata

θ1 Microscopii, Latinized as Theta1 Microscopii, is a suspected binary star[10] system in the southern constellation of Microscopium. It is visible to the naked eye was a faint, white-hued point of light with an apparent visual magnitude of 4.82.[2] The distance to this system is approximately 179 light years based on parallax.[1]

A light curve for Theta1 Microscopii, plotted from TESS data[11]

The primary is an α2 CVn variable with a period of 2.125 days and a magnitude ranging from 4.77 to 4.87,[4] as well as an Ap star, a chemically peculiar star with strong metallic lines in its spectrum.[3][6] It is an A-type main-sequence star with a stellar classification of A7VpSrCrEu,[3] where the suffix notation indicates abundance anomalies of strontium, chromium, and europium. The star is 437 million years old with 2.3 times the mass of the Sun and 2.4 times the Sun's radius. It is radiating 36 times the luminosity of the Sun from its photosphere at an effective temperature of 9,240 K.[7]

Its companion is a magnitude 7.42 star at an angular separation of 0.10″ from the primary along a position angle of 46°, as of 2018.[12]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference abt was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference AAVSO was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference XHIP was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Sikora2018 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).