PROFILPELAJAR.COM

BG Indi
	; Light curves from TESS data for the two eclipsing binaries comprising BG Indi, adapted from Borkovits et al. (2021)
Observation data; Epoch J2000 Equinox J2000
Constellation	Indus
Right ascension	21h 58m 30.04050s
Declination	−59° 00′ 43.4938″
Apparent magnitude (V)	6.141 (6.11 - 6.36)
Characteristics
Spectral type	F3V
Variable type	Algol
Astrometry
Radial velocity (Rv)	19.0 ± 0.5 km/s
Proper motion (μ)	RA: 24.729 mas/yr ; Dec.: 15.315 mas/yr
Parallax (π)	19.5917 ± 0.2028 mas
Distance	166 ± 2 ly ; (51.0 ± 0.5 pc)
Absolute magnitude (MV)	2.45 / 3.02 / 7.23 / 7.83
Absolute bolometric; magnitude (Mbol)	2.45 / 3.04 / 6.72 / 7.09
Orbit
Primary	BG Ind A
Companion	BG Ind B
Period (P)	720.9+3.4; −3.1 d yr
Semi-major axis (a)	540.4+2.7; −2.2 R☉
Eccentricity (e)	0.209+0.028; −0.048
Inclination (i)	85.5+3.1; −6.3°
Periastron epoch (T)	2458699+14; −21
Argument of periastron (ω); (secondary)	1.6+9.2; −8.8°
Semi-amplitude (K1); (primary)	12.57+0.17; −0.24 km/s
Semi-amplitude (K2); (secondary)	26.02+0.31; −0.50 km/s
Orbit
Primary	BG Ind Aa
Companion	BG Ind Ab
Period (P)	1.464065(2) d yr
Semi-major axis (a)	7.602+0.038; −0.043 R☉
Eccentricity (e)	0
Inclination (i)	73.27+0.06; −0.13°
Periastron epoch (T)	2458326.1362+0.0011; −0.0012
Semi-amplitude (K1); (primary)	120.47+1.12; −0.75 km/s
Semi-amplitude (K2); (secondary)	130.99+0.48; −0.50 km/s
Orbit
Primary	BG Ind Ba
Companion	BG Ind Bb
Period (P)	0.528349(2) d yr
Semi-major axis (a)	3.025+0.011; −0.016 R☉
Eccentricity (e)	0
Inclination (i)	84.29+0.85; −0.87°
Periastron epoch (T)	2458325.8072+0.0025; −0.0022
Semi-amplitude (K1); (primary)	138.98+1.23; −1.39 km/s
Semi-amplitude (K2); (secondary)	149.25+1.09; −1.13 km/s
Details
κ1 Ind Aa
Mass	1.432+0.015; −0.024 M☉
Radius	2.339+0.016; −0.021 R☉
Luminosity (bolometric)	8.433+0.199; −0.169 L☉
Surface gravity (log g)	3.852+0.011; −0.005 cgs
Temperature	6442+29; −28 K
κ1 Ind Ab
Mass	1.315+0.026; −0.023 M☉
Radius	1.592+0.047; −0.019 R☉
Luminosity (bolometric)	4.934+0.279; −0.179 L☉
Surface gravity (log g)	4.150+0.007; −0.016 cgs
Temperature	6816±26 K
κ1 Ind Ba
Mass	0.688+0.008; −0.011 M☉
Radius	0.642+0.005; −0.007 R☉
Luminosity (bolometric)	0.167±0.009 L☉
Surface gravity (log g)	4.660+0.003; −0.002 cgs
Temperature	4609+48; −49 K
κ1 Ind Bb
Mass	0.640+0.010; −0.011 M☉
Radius	0.611+0.008; −0.009 R☉
Luminosity (bolometric)	0.118±0.009 L☉
Surface gravity (log g)	4.672±0.004 cgs
Temperature	4327+62; −57 K
Other designations
	κ1 Ind, BG Ind, CD−59° 7830, FK5 3752, HD 208496, HIP 108478, HR 8369, SAO 247247
Database references
SIMBAD	data

BG Indi, also known as κ¹ Indi (Kappa¹ Indi) is a multiple star system in the southern constellation of Indus. Its average apparent magnitude is 6.141,^[3] meaning it can only be seen by the naked eye under exceptionally good viewing conditions. Stellar parallax measurements by Gaia put the system at about 166 light-years (51 parsecs) away.^[2]

Nomenclature

The star system is most commonly known as BG Indi. BG Indi is its variable star designation, a unique name given to variable stars based on its constellation and when it was discovered to be a variable.^[4] It also has the name κ¹ Indi (Latinized to Kappa¹ Indi), which is its Bayer designation.^[6]

Properties

BG Indi consists of four stars in two compact, orbiting pairs. The brighter pair is known as BG Indi A, and consists of two F-type main-sequence stars Aa and Ab. As F-type stars, they are more massive, larger, and hotter than the Sun,^[1] and with a metallicity of −0.2 ± 0.1, it is less metal-rich than the Sun. BG Indi is about 2.65 billion years old, and is just starting to leave the main sequence.^[8]

BG Indi Aa and Ab orbit each other on a circular orbit, with a period of 1.46 days. Periodically, one star passes in front of the other, blocking its light. Therefore, the apparent magnitude varies from 6.11 to 6.36.^[4] Its status as an eclipsing binary was confirmed by J. Manfroid and G. Mathys in 1984.^[5]

The other two stars, BG Indi Ba and Bb, form the pair BG Indi B. Both are less massive than the Sun, and orbit each other on a tighter orbit with a period of 0.53 days. Collectively, BG Indi A and B orbit each other with a period of 720.9 days with a moderate eccentricity of 0.209. All three orbits are likely to be more or less coplanar. BG Indi is the nearest quadruple star system consisting of two eclipsing binaries.^[1]

Notes

^ ^a ^b This refers to the epoch of primary transit.

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Borkovits, T.; Rappaport, S. A.; Maxted, P F L.; Terentev, I.; Omohundro, M.; Gagliano, R.; Jacobs, T.; Kristiansen, M. H.; Lacourse, D.; Schwengeler, H. M.; Vanderburg, A.; Blackford, M. G. (2021). "BG Ind: The nearest doubly eclipsing, compact hierarchical quadruple system". Monthly Notices of the Royal Astronomical Society. 503 (3): 3759–3774. arXiv:2103.00925. doi:10.1093/mnras/stab621.
^ ^a ^b ^c ^d ^e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27 – L30. Bibcode:2000A&A...355L..27H.
^ ^a ^b ^c Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
^ ^a ^b Manfroid, J.; Mathys, G. (1984). "The Bright Eclipsing Binary HD 208496". Information Bulletin on Variable Stars. 2616 (2616): 1. Bibcode:1984IBVS.2616....1M.
^ ^a ^b ^c "* kap01 Ind". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-07-17.
^ Holmberg, J.; Nordström, B.; Andersen, J. (2007). "The Geneva-Copenhagen survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk". Astronomy and Astrophysics. 475 (2): 519. arXiv:0707.1891. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. S2CID 119054949.
^ Rozyczka, M.; Kaluzny, J.; Pych, W.; Konacki, M.; Małek, K.; Mankiewicz, L.; Sokołowski, M.; Żarnecki, A. F. (2011). "Absolute properties of BG Ind - a bright F3 system just leaving the main sequence". Monthly Notices of the Royal Astronomical Society. 414 (3): 2479–2485. arXiv:1010.1355. Bibcode:2011MNRAS.414.2479R. doi:10.1111/j.1365-2966.2011.18567.x. S2CID 118422112.

[primary-8] This refers to the epoch of primary transit.

[Borkovits-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Borkovits, T.; Rappaport, S. A.; Maxted, P F L.; Terentev, I.; Omohundro, M.; Gagliano, R.; Jacobs, T.; Kristiansen, M. H.; Lacourse, D.; Schwengeler, H. M.; Vanderburg, A.; Blackford, M. G. (2021). "BG Ind: The nearest doubly eclipsing, compact hierarchical quadruple system". Monthly Notices of the Royal Astronomical Society. 503 (3): 3759–3774. arXiv:2103.00925. doi:10.1093/mnras/stab621.

[GaiaDR2-2] Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

[TYC2-3] Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27 – L30. Bibcode:2000A&A...355L..27H.

[GCVS-4] Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.

[Manfroid-5] Manfroid, J.; Mathys, G. (1984). "The Bright Eclipsing Binary HD 208496". Information Bulletin on Variable Stars. 2616 (2616): 1. Bibcode:1984IBVS.2616....1M.

[SIMBAD-6] "* kap01 Ind". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-07-17.

[7] Holmberg, J.; Nordström, B.; Andersen, J. (2007). "The Geneva-Copenhagen survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk". Astronomy and Astrophysics. 475 (2): 519. arXiv:0707.1891. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. S2CID 119054949.

[Rozyczka-9] Rozyczka, M.; Kaluzny, J.; Pych, W.; Konacki, M.; Małek, K.; Mankiewicz, L.; Sokołowski, M.; Żarnecki, A. F. (2011). "Absolute properties of BG Ind - a bright F3 system just leaving the main sequence". Monthly Notices of the Royal Astronomical Society. 414 (3): 2479–2485. arXiv:1010.1355. Bibcode:2011MNRAS.414.2479R. doi:10.1111/j.1365-2966.2011.18567.x. S2CID 118422112.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[note 1]

[8]