Astronomy:HD 174881
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Lyra[1] |
| Right ascension | 18h 51m 35.8920s[2] |
| Declination | +28° 47′ 01.219″[2] |
| Apparent magnitude (V) | +6.209[3] |
| Characteristics | |
| Evolutionary stage | red giant branch (A) red clump (B)[4] |
| Spectral type | K1II-III[4] |
| Astrometry | |
| Radial velocity (Rv) | −19.101+0.034 −0.043[4] km/s |
| Proper motion (μ) | RA: +1.649[2] mas/yr Dec.: +4.811[2] mas/yr |
| Parallax (π) | 2.525+0.014 −0.015[4] mas |
| Distance | 1,290+7.8 −7.2 ly (396.0+2.4 −2.2 pc) |
| Absolute magnitude (MV) | −1.462±0.065 (A)[4] −1.042±0.066 (B)[4] |
| Orbit[4] | |
| Primary | A |
| Companion | B |
| Period (P) | 215.1166+0.0092 −0.0072 days |
| Semi-major axis (a) | 1.3336+0.0060 −0.0051 astronomical unit|AU |
| Eccentricity (e) | 0.12162+0.00063 −0.00064 |
| Inclination (i) | 38.73±0.17° |
| Longitude of the node (Ω) | 263.65±0.15° |
| Argument of periapsis (ω) (primary) | 101.98+0.36 −0.34° |
| Semi-amplitude (K1) (primary) | 21.594±0.053 km/s |
| Semi-amplitude (K2) (secondary) | 20.924+0.062 −0.057 km/s |
| Details[4] | |
| A | |
| Mass | 3.367+0.045 −0.041 M☉ |
| Radius | 34.0±1.3 R☉ |
| Luminosity | 456 L☉ |
| Surface gravity (log g) | 1.903±0.033 cgs |
| Temperature | 4,620±150 K |
| Age | 255–273 Myr |
| B | |
| Mass | 3.476±0.043 M☉ |
| Radius | 22.7±1.8 R☉ |
| Luminosity | 250 L☉ |
| Surface gravity (log g) | 2.262+0.075 −0.059 cgs |
| Temperature | 4,880±150 K |
| Age | 255–273 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 174881 is a binary star located in the northern constellation of Lyra, the lyre. This system has an apparent visual magnitude of +6.209,[3] making it faintly visible to the naked eye only in very dark skies, with no light pollution. Based on dynamical parallax measurements inferred from the binary's orbit, it is about 1,300 light-years distant. At that distance, the apparent magnitude is diminished by 0.22 magnitudes due to extinction by gas and dust between Earth and HD 174881.[4]
This binary system is composed of two evolved giant stars that exhausted their hydrogen supply at their core and expanded in size. They complete an orbit around each other every 215 days (7.1 months), and are separated by 1.3 astronomical units. The orbit is close to circular, with a low eccentricity of 0.12. The primary and secondary star are over three times more massive than the Sun, with radii 34 and 23 times higher, respectively, and luminosities 460 and 250 times solar. Their effective temperatures are 4,620 and 4,880 K,[4] giving them an orange hue typical of K-type stars.[5] The age of the system is estimated at 250 million years.[4]
HD 174881 was first detected as a binary in 1995 by spectroscopic observations. Subsequently, observations have been made that significantly improved the orbit and spatially resolved the binary for the first time, as well as providing valuable tests of stellar evolution in evolved stars.[4]
There is evidence of an infrared excess around this system, suggesting it is surrounded by cold dust with temperatures between 15 and 20 K. This could also explain the observed extinction.[4]
References
- ↑ "Find the constellation which contains given sky coordinates". https://djm.cc/constellation.html.
- ↑ 2.0 2.1 2.2 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000-03-01). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 Torres, Guillermo; Boden, Andrew F.; Monnier, John D.; van Belle, Gerard T. (December 2024). "Absolute Dimensions of the Interferometric Binary HD 174881: A Test of Stellar Evolution Models for Evolved Stars" (in en). The Astrophysical Journal 977 (1): 43. doi:10.3847/1538-4357/ad8dcc. ISSN 0004-637X. Bibcode: 2024ApJ...977...43T.
- ↑ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html. Retrieved 2012-01-16.
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