AO Serpentis

AO Serpentis
	; A visual band light curve for AO Serpentis, plotted from ASAS-SN data
Observation data; Epoch J2000 Equinox J2000
Constellation	Serpens
Right ascension	15h 58m 18.410s
Declination	+17° 16′ 10.00″
Apparent magnitude (V)	11.04±0.09
Characteristics
Spectral type	A2
B−V color index	0.22
Variable type	β Per + δ Sct
Astrometry
Primary
Proper motion (μ)	RA: −8.236 mas/yr ; Dec.: −10.444 mas/yr
Parallax (π)	2.2539 ± 0.0229 mas
Distance	1,450 ± 10 ly ; (444 ± 5 pc)
Absolute magnitude (MV)	+1.88±0.03
Secondary
Absolute magnitude (MV)	+5.17±0.05
Orbit
Period (P)	0.8793496±0.0000047 d
Semi-major axis (a)	5.59±0.05 R☉
Inclination (i)	90.0±1.5°
Longitude of the node (Ω)	3.645±0.002°
Periastron epoch (T)	2,457,127.5076±0.0041 HJD
Semi-amplitude (K1); (primary)	51.6±1.1 km/s
Semi-amplitude (K2); (secondary)	270.3±3.6 km/s
Details
Primary
Mass	2.55±0.09 M☉
Radius	1.64±0.02 R☉
Luminosity	14.45+0.69; −0.65 L☉
Surface gravity (log g)	4.42±0.01 cgs
Temperature	8,820±62 K
Rotational velocity (v sin i)	90±18 km/s
Secondary
Mass	0.49±0.02 M☉
Radius	1.38±0.02 R☉
Luminosity	0.93+0.05; −0.04 L☉
Surface gravity (log g)	3.85±0.01 cgs
Temperature	4,786±11 K
Other designations
	AO Ser, BD+17°2942, TYC 1496-3-1, GSC 01496-00003, 2MASS J15581840+1716101
Database references
SIMBAD	data

AO Serpentis is an eclipsing binary star system in the Serpens Caput segment of the Serpens constellation. It is invisible to the naked eye with a typical apparent visual magnitude of 11.04.^[3] Variable star observers record a peak magnitude of 10.7, dropping to 12.0 during the primary eclipse and 10.8 from the secondary eclipse.^[7] The distance to this system is approximately 1,450 light years based on parallax measurements.^[2]

This system was discovered by C. Hoffmeister to be an Algol-type eclipsing binary in 1935.^[8] The following year, P. Guthnick and R. Prager reported a brightness variation between 10.5 and 12.0.^[9] In 2004, S. -L. Kim and associates determined that one of the components of this system is pulsating with a short period.^[10]

This is a semi-detached binary star system with the secondary component completely filling its Roche lobe while the primary is 61% full. It has an orbital period of 21.1 hours and a semimajor axis of just 5.6 times the radius of the Sun. The orbital plane is inclined by an angle of 90° to the line of sight, causing the secondary component to be completely eclipsed once per orbit.^[5] The orbital period shows long-term cyclic variations, changing by up to 0.0051 days every 17.32 years. This may be due to magnetic activity cycles or the influence of a third body. The orbital period as a whole is steadily decreasing at the rate of (−5.39±0.03)×10⁻⁷ days yr⁻¹ due to loss of mass and angular momentum by the system.^[4]

The physical properties of the stellar components can be explained by a mass transfer. At some point in the past, mass flowed from the (at the time) more massive and evolved secondary component. This has left the primary as an A-type main-sequence star while the secondary is less massive but overly large. The hotter primary component is a Delta Scuti variable that is undergoing radial pulsation with a dominant frequency of 21.852 days⁻¹ and a secondary frequency of 23.484 days⁻¹.^[5]

References

^ "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.
^ ^a ^b ^c ^d ^e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862, ISBN 978-0333750889.
^ ^a ^b ^c Yang, Y. -G.; et al. (April 2010), "Photometric Properties for Selected Algol-type Binaries. II. AO Serpentis and V338 Herculis", The Astronomical Journal, 139 (4): 1360–1368, Bibcode:2010AJ....139.1360Y, doi:10.1088/0004-6256/139/4/1360, S2CID 122306646.
^ ^a ^b ^c ^d ^e Park, Jang-Ho; et al. (December 2020), "Physical Nature of the Eclipsing δ Scuti Star AO Serpentis", The Astronomical Journal, 160 (6): 9, arXiv:2010.02441, Bibcode:2020AJ....160..247P, doi:10.3847/1538-3881/abbef4, S2CID 222141749, 247.
^ "AO Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-02-19.
^ Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
^ Hoffmeister, Cuno (June 1935), "162 neue Veräderliche", Astronomische Nachrichten, 255 (22): 401, Bibcode:1935AN....255..401H, doi:10.1002/asna.19352552202.
^ Guthnick, P.; Prager, R. (October 1936), "Benennung von veränderlichen Sternen", Astronomische Nachrichten, 260 (22): 393, Bibcode:1936AN....260..393G, doi:10.1002/asna.19362602202.
^ Kim, S. -L.; et al. (June 2004), "Discovery of a short-periodic pulsating component in the Algol-type eclipsing binary system AO Ser", Information Bulletin on Variable Stars, 5538: 1, Bibcode:2004IBVS.5538....1K.

[ASAS-SN-1] "ASAS-SN Variable Stars Database". ASAS-SN Variable Stars Database. ASAS-SN. Retrieved 6 January 2022.

[GaiaEDR3-2] Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[Høg_et_al_2000-3] Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862, ISBN 978-0333750889.

[Yang_et_al_2010-4] Yang, Y. -G.; et al. (April 2010), "Photometric Properties for Selected Algol-type Binaries. II. AO Serpentis and V338 Herculis", The Astronomical Journal, 139 (4): 1360–1368, Bibcode:2010AJ....139.1360Y, doi:10.1088/0004-6256/139/4/1360, S2CID 122306646.

[Park_et_al_2020-5] Park, Jang-Ho; et al. (December 2020), "Physical Nature of the Eclipsing δ Scuti Star AO Serpentis", The Astronomical Journal, 160 (6): 9, arXiv:2010.02441, Bibcode:2020AJ....160..247P, doi:10.3847/1538-3881/abbef4, S2CID 222141749, 247.

[SIMBAD-6] "AO Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-02-19.

[Samus_et_al_2017-7] Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.

[Hoffmeister1935-8] Hoffmeister, Cuno (June 1935), "162 neue Veräderliche", Astronomische Nachrichten, 255 (22): 401, Bibcode:1935AN....255..401H, doi:10.1002/asna.19352552202.

[Guthnick_Prager_1936-9] Guthnick, P.; Prager, R. (October 1936), "Benennung von veränderlichen Sternen", Astronomische Nachrichten, 260 (22): 393, Bibcode:1936AN....260..393G, doi:10.1002/asna.19362602202.

[Kim_et_al_2004-10] Kim, S. -L.; et al. (June 2004), "Discovery of a short-periodic pulsating component in the Algol-type eclipsing binary system AO Ser", Information Bulletin on Variable Stars, 5538: 1, Bibcode:2004IBVS.5538....1K.

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AO Serpentis

References

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