DD Microscopii

DD Microscopii

A visual band light curve for DD Microscopii, plotted from ASAS-SN data[1]
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 21h 00m 06.3576s[2]
Declination −42° 38′ 44.9350″[2]
Apparent magnitude (V) 11.0 - 11.7[3]
Characteristics
Spectral type K2 III[4] or K5/M0 IIIe[5]
U−B color index +0.37[6]
B−V color index +1.57[6]
Variable type Z And[3]
Astrometry
Proper motion (μ) RA: −10.080 mas/yr[2]
Dec.: −2.035 mas/yr[2]
Parallax (π)0.1072 ± 0.0205 mas[2]
Distance1-2,000[4] pc
Orbit[7]
Primaryyellow giant
CompanionWhite dwarf
Period (P)1,442 d
Eccentricity (e)0.22
Periastron epoch (T)2,445,560
Argument of periastron (ω)
(primary)		261°
Semi-amplitude (K1)
(primary)		4.6 km/s
Details
yellow giant
Mass1.45[8] M☉
Radius103[9] R☉
Surface gravity (log g)0.25[8] cgs
Temperature3,941[8] K
Metallicity [Fe/H]−0.93±0.06[10] dex
Rotational velocity (v sin i)<3[7] km/s
Other designations
DD Mic, CD−43°14304, GSC 07973-00869[11]
Database references
SIMBADdata

DD Microscopii, also known as CD−43°14304, is a binary star system in the constellation Microscopium. The system has a combined average apparent magnitude around 11,[12] making it readily visible in telescopes but not to the naked eye. It is thought to be at a distance of one or two thousand parsecs,[4] although parallax measurements place the system at a distance of around 30,000 light years.[2]

It is a symbiotic star system composed of an orange giant with a class of either K2 III[4] or K5/M0 IIIe.[5] Both stellar classifications of the primary indicate a red giant, but one has a regular spectrum while the other shows an evolved star with the characteristics of a K5 and M0 giant star plus emission lines in its spectrum. The secondary is a white dwarf in close orbit, ionizing the stellar wind of the larger star.[citation needed] The giant star and white dwarf both take about 4 years to orbit each other.[7]

The primary has an enlarged radius of 103 R☉[9] and an effective temperature of 3,941 K,[8] giving a red hue when viewed through a telescope. DD Microscopii is extremely metal deficient, with an iron abundance only 12% of the Sun,[10] and spins leisurely with a projected rotational velocity lower than 3 km/s.[7] The star system has its origin in the galactic halo of the Milky Way as indicated by the high galactic latitude.[4] DD Microscopii is cataloged as a Z Andromedae variable, a type of symbiotic binary with occasional outbursts. It fluctuates between magnitudes 11.0 and 11.7 over a span of almost 400 days.[13]

  1. ^ Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference EDR3 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference pereira2009 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference SL1988 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Munari1992 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Schimd1998 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Anders2022 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Stassun2019 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Gałan2016 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Kazarovets2006 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Watson2006 was invoked but never defined (see the help page).