  | |
| Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 43m 12.19841s [1] |
| Declination | −79° 04′ 12.3685″ [1] |
| Apparent magnitude (V) | 6.02 to 6.68 [2] |
| Characteristics | |
| Spectral type | A8 IV + A8 IV [3] |
| U−B color index | +0.08 [4] |
| B−V color index | +0.24 [4] |
| Variable type | Algol + δ Scuti [2] |
| Astrometry | |
| Radial velocity (Rv) | 16.1±4.3 [5] km/s |
| Proper motion (μ) |
RA: −27.263
mas/
yr
[1] Dec.: +28.179 mas/ yr [1] |
| Parallax (π) | 10.137 ± 0.0213 mas [1] |
| Distance | 321.7 ± 0.7
ly (98.6 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.21 [6] |
| Orbit | |
| Period (P) | 1.6699 d [7] |
| Semi-major axis (a) | 9.14 R☉ [8] |
| Eccentricity (e) | 0.00 [7] |
| Inclination (i) | 83.4 [8]° |
| Periastron epoch (T) | 2,438,380.526 JD [7] |
|
Argument of periastron (ω) (secondary) | 0.00° |
|
Semi-amplitude (K1) (primary) | 136.1 [7] km/s |
| Semi-amplitude (K2) (secondary) | 138.9 [7] km/s |
| Details | |
| Luminosity | 17.3±1.2 [8] (combined) L☉ |
| Metallicity [Fe/H] | −0.38±0.06 [9] or +0.17 [10] dex |
| Age | 912±21 [9] or 9.5 [11] Myr |
| A | |
| Mass | 1.86±0.02 [7] M☉ |
| Radius | 2.14±0.06 [7] R☉ |
| Surface gravity (log g) | 4.05±0.02 [7] cgs |
| Temperature | 8,050±200 [12] K |
| Rotational velocity (v sin i) | 64±6 [10] km/s |
| B | |
| Mass | 1.82±0.02 [7] M☉ |
| Radius | 2.34±0.06 [7] R☉ |
| Surface gravity (log g) | 3.96±0.02 [7] cgs |
| Temperature | 7,444±129 [13] K |
| Rotational velocity (v sin i) | 70±6 [10] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 75747, also known as HR 3524 or RS Chamaeleontis (RS Cha), is a binary star located in the southern circumpolar constellation Chamaeleon. It has an average apparent magnitude of 6.05, [16] making it barely visible to the naked eye. The system is located relatively close at a distance of 322 light years based on Gaia DR3 parallax measurements [1] but is receding with a somewhat constrained heliocentric radial velocity of 16.1 km/s. [5] It has an absolute magnitude of +1.21. [6]
HD 75747 was known to be variable since 1960 based on observations by A. W. J. Cousins. [18] The system was first observed as an eclipsing binary in 1967 by astronomers P. A. T. Wild and H. C. Lagerweij. J. [19] Andersen deduced a circular orbit with a period of 1.66 days for the system. [7] Subsequent observations revealed that one of the components as a δ Scuti variable. [20] RS Cha is an Algol-type eclipsing binary ranging from 6.02 to 6.58 or 6.68 within 1.6699 days, depending on the eclipse. [2] This system is part of the η Chamaeleontis association, a group of young stars moving with Eta Cha, and Eta Cha is just eight arc-minutes to the northwest of RS Cha. [21]
Both components have a stellar classification of A8 IV, indicating that both objects are slightly evolved A-type subgiants. RS Cha A and B have masses nearly double of the Sun's and 2.14 - 2.34 times the radius of the Sun. [7] They radiate 17.3 times the luminosity of the Sun [8] from its photosphere at effective temperatures of 8,050 K [12] and 7,444 K respectively, [13] giving the object a white hue. RS Cha was originally thought to be 912 million years old, [9] meaning that both stars were evolving off the main sequence. However, astronomer E. Alecian and colleagues re-examined the age of the system and it turns out that HD 75747 is only 9 million years old, [11] making them pre-main sequence stars. The components rotation periods are synchronous to the orbital period, having projected rotational velocities of 64 km/s and 70 km/s respectively. [10]
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode: 2017ARep...61...80S. doi: 10.1134/S1063772917010085. eISSN 1562-6881. ISSN 1063-7729. S2CID 125853869.
- ^ Jones, D. H. P. (1969). "Spectroscopic Observations of two Eclipsing Binaries". Monthly Notes of the Astronomical Society of South Africa. 28: 5. Bibcode: 1969MNSSA..28....5J. ISSN 0024-8266.
- ^ a b Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode: 1966CoLPL...4...99J.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053. Bibcode: 2006AstL...32..759G. doi: 10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
- ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b c d e f g h i j k l m Andersen, J. (November 1975). "Spectroscopic observations of eclipsing binaries. I. Description of methods, and results for RS Chamaeleontis and chi 2 Hydrae". Astronomy and Astrophysics. 44: 445–458. Bibcode: 1975A&A....44..445A. ISSN 0004-6361.
- ^ a b c d Clausen, J. V.; Nordstrom, B. (March 1980). "Four-colour photometry of eclipsing binaries. XIa". Astronomy and Astrophysics. 83: 339–347. Bibcode: 1980A&A....83..339C. ISSN 0004-6361.
- ^ a b c Kovaleva, D. A. (December 2001). "Age and metallicity estimates for moderate-mass stars in eclipsing binaries". Astronomy Reports. 45 (12): 972–983. Bibcode: 2001ARep...45..972K. doi: 10.1134/1.1426128. eISSN 1562-6881. ISSN 1063-7729. S2CID 121028634.
- ^ a b c d Alecian, E.; Catala, C.; Van't Veer-Menneret, C.; Goupil, M.-J.; Balona, L. (14 October 2005). "Pulsations and metallicity of the pre-main sequence eclipsing spectroscopic binary RS Cha". Astronomy & Astrophysics. 442 (3): 993–1002. Bibcode: 2005A&A...442..993A. doi: 10.1051/0004-6361:20041906. eISSN 1432-0746. ISSN 0004-6361.
- ^ a b Alecian, E.; Goupil, M.-J.; Lebreton, Y.; Dupret, M.-A.; Catala, C. (11 January 2007). "Calibration of the pre-main sequence RS Chamaleontis binary system". Astronomy & Astrophysics. 465 (1): 241–248. arXiv: astro-ph/0610947. Bibcode: 2007A&A...465..241A. doi: 10.1051/0004-6361:20065822. eISSN 1432-0746. ISSN 0004-6361.
- ^ a b Relyea, L. J.; Kurucz, R. L. (May 1978). "A theoretical analysis of UVBY photometry". The Astrophysical Journal Supplement Series. 37: 45. Bibcode: 1978ApJS...37...45R. doi: 10.1086/190517. eISSN 1538-4365. ISSN 0067-0049.
- ^ a b David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv: 1501.03154. Bibcode: 2015ApJ...804..146D. doi: 10.1088/0004-637X/804/2/146. eISSN 1538-4357.
- ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode: 1879RNAO....1.....G.
- ^ "RS Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved January 12, 2023.
- ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H. ISSN 0004-6361.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ Cousins, A. W. J. (1960). "New Bright Variable Stars". Monthly Notes of the Astronomical Society of South Africa. 19: 56. Bibcode: 1960MNSSA..19...56C. ISSN 0024-8266.
- ^ Wild, P. A. T.; Lagerweij, H. C. (1967). "Preliminary Photometric Elements of the Eclipsing Binary System 9 Cha". Monthly Notes of the Astronomical Society of South Africa. 26: 144. Bibcode: 1967MNSSA..26..144W. ISSN 0024-8266.
- ^ McInally, C. J.; Austin, R. D. (September 1977). "RS Cha: a delta Scuti Variable". Information Bulletin on Variable Stars. 1334: 1. Bibcode: 1977IBVS.1334....1M. ISSN 0374-0676.
- ^ Murphy, Simon J.; Lawson, Warrick A.; Bessell, Michael S. (20 August 2013). "Re-examining the membership and origin of the ϵ Cha association". Monthly Notices of the Royal Astronomical Society. 435 (2): 1325–1349. arXiv: 1305.4177. Bibcode: 2013MNRAS.435.1325M. doi: 10.1093/mnras/stt1375. eISSN 1365-2966. ISSN 0035-8711.
| |
| Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 43m 12.19841s [1] |
| Declination | −79° 04′ 12.3685″ [1] |
| Apparent magnitude (V) | 6.02 to 6.68 [2] |
| Characteristics | |
| Spectral type | A8 IV + A8 IV [3] |
| U−B color index | +0.08 [4] |
| B−V color index | +0.24 [4] |
| Variable type | Algol + δ Scuti [2] |
| Astrometry | |
| Radial velocity (Rv) | 16.1±4.3 [5] km/s |
| Proper motion (μ) |
RA: −27.263
mas/
yr
[1] Dec.: +28.179 mas/ yr [1] |
| Parallax (π) | 10.137 ± 0.0213 mas [1] |
| Distance | 321.7 ± 0.7
ly (98.6 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.21 [6] |
| Orbit | |
| Period (P) | 1.6699 d [7] |
| Semi-major axis (a) | 9.14 R☉ [8] |
| Eccentricity (e) | 0.00 [7] |
| Inclination (i) | 83.4 [8]° |
| Periastron epoch (T) | 2,438,380.526 JD [7] |
|
Argument of periastron (ω) (secondary) | 0.00° |
|
Semi-amplitude (K1) (primary) | 136.1 [7] km/s |
| Semi-amplitude (K2) (secondary) | 138.9 [7] km/s |
| Details | |
| Luminosity | 17.3±1.2 [8] (combined) L☉ |
| Metallicity [Fe/H] | −0.38±0.06 [9] or +0.17 [10] dex |
| Age | 912±21 [9] or 9.5 [11] Myr |
| A | |
| Mass | 1.86±0.02 [7] M☉ |
| Radius | 2.14±0.06 [7] R☉ |
| Surface gravity (log g) | 4.05±0.02 [7] cgs |
| Temperature | 8,050±200 [12] K |
| Rotational velocity (v sin i) | 64±6 [10] km/s |
| B | |
| Mass | 1.82±0.02 [7] M☉ |
| Radius | 2.34±0.06 [7] R☉ |
| Surface gravity (log g) | 3.96±0.02 [7] cgs |
| Temperature | 7,444±129 [13] K |
| Rotational velocity (v sin i) | 70±6 [10] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 75747, also known as HR 3524 or RS Chamaeleontis (RS Cha), is a binary star located in the southern circumpolar constellation Chamaeleon. It has an average apparent magnitude of 6.05, [16] making it barely visible to the naked eye. The system is located relatively close at a distance of 322 light years based on Gaia DR3 parallax measurements [1] but is receding with a somewhat constrained heliocentric radial velocity of 16.1 km/s. [5] It has an absolute magnitude of +1.21. [6]
HD 75747 was known to be variable since 1960 based on observations by A. W. J. Cousins. [18] The system was first observed as an eclipsing binary in 1967 by astronomers P. A. T. Wild and H. C. Lagerweij. J. [19] Andersen deduced a circular orbit with a period of 1.66 days for the system. [7] Subsequent observations revealed that one of the components as a δ Scuti variable. [20] RS Cha is an Algol-type eclipsing binary ranging from 6.02 to 6.58 or 6.68 within 1.6699 days, depending on the eclipse. [2] This system is part of the η Chamaeleontis association, a group of young stars moving with Eta Cha, and Eta Cha is just eight arc-minutes to the northwest of RS Cha. [21]
Both components have a stellar classification of A8 IV, indicating that both objects are slightly evolved A-type subgiants. RS Cha A and B have masses nearly double of the Sun's and 2.14 - 2.34 times the radius of the Sun. [7] They radiate 17.3 times the luminosity of the Sun [8] from its photosphere at effective temperatures of 8,050 K [12] and 7,444 K respectively, [13] giving the object a white hue. RS Cha was originally thought to be 912 million years old, [9] meaning that both stars were evolving off the main sequence. However, astronomer E. Alecian and colleagues re-examined the age of the system and it turns out that HD 75747 is only 9 million years old, [11] making them pre-main sequence stars. The components rotation periods are synchronous to the orbital period, having projected rotational velocities of 64 km/s and 70 km/s respectively. [10]
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211. Bibcode: 2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode: 2017ARep...61...80S. doi: 10.1134/S1063772917010085. eISSN 1562-6881. ISSN 1063-7729. S2CID 125853869.
- ^ Jones, D. H. P. (1969). "Spectroscopic Observations of two Eclipsing Binaries". Monthly Notes of the Astronomical Society of South Africa. 28: 5. Bibcode: 1969MNSSA..28....5J. ISSN 0024-8266.
- ^ a b Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode: 1966CoLPL...4...99J.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv: 1606.08053. Bibcode: 2006AstL...32..759G. doi: 10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
- ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971. Bibcode: 2012AstL...38..331A. doi: 10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b c d e f g h i j k l m Andersen, J. (November 1975). "Spectroscopic observations of eclipsing binaries. I. Description of methods, and results for RS Chamaeleontis and chi 2 Hydrae". Astronomy and Astrophysics. 44: 445–458. Bibcode: 1975A&A....44..445A. ISSN 0004-6361.
- ^ a b c d Clausen, J. V.; Nordstrom, B. (March 1980). "Four-colour photometry of eclipsing binaries. XIa". Astronomy and Astrophysics. 83: 339–347. Bibcode: 1980A&A....83..339C. ISSN 0004-6361.
- ^ a b c Kovaleva, D. A. (December 2001). "Age and metallicity estimates for moderate-mass stars in eclipsing binaries". Astronomy Reports. 45 (12): 972–983. Bibcode: 2001ARep...45..972K. doi: 10.1134/1.1426128. eISSN 1562-6881. ISSN 1063-7729. S2CID 121028634.
- ^ a b c d Alecian, E.; Catala, C.; Van't Veer-Menneret, C.; Goupil, M.-J.; Balona, L. (14 October 2005). "Pulsations and metallicity of the pre-main sequence eclipsing spectroscopic binary RS Cha". Astronomy & Astrophysics. 442 (3): 993–1002. Bibcode: 2005A&A...442..993A. doi: 10.1051/0004-6361:20041906. eISSN 1432-0746. ISSN 0004-6361.
- ^ a b Alecian, E.; Goupil, M.-J.; Lebreton, Y.; Dupret, M.-A.; Catala, C. (11 January 2007). "Calibration of the pre-main sequence RS Chamaleontis binary system". Astronomy & Astrophysics. 465 (1): 241–248. arXiv: astro-ph/0610947. Bibcode: 2007A&A...465..241A. doi: 10.1051/0004-6361:20065822. eISSN 1432-0746. ISSN 0004-6361.
- ^ a b Relyea, L. J.; Kurucz, R. L. (May 1978). "A theoretical analysis of UVBY photometry". The Astrophysical Journal Supplement Series. 37: 45. Bibcode: 1978ApJS...37...45R. doi: 10.1086/190517. eISSN 1538-4365. ISSN 0067-0049.
- ^ a b David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv: 1501.03154. Bibcode: 2015ApJ...804..146D. doi: 10.1088/0004-637X/804/2/146. eISSN 1538-4357.
- ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode: 1879RNAO....1.....G.
- ^ "RS Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved January 12, 2023.
- ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H. ISSN 0004-6361.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- ^ Cousins, A. W. J. (1960). "New Bright Variable Stars". Monthly Notes of the Astronomical Society of South Africa. 19: 56. Bibcode: 1960MNSSA..19...56C. ISSN 0024-8266.
- ^ Wild, P. A. T.; Lagerweij, H. C. (1967). "Preliminary Photometric Elements of the Eclipsing Binary System 9 Cha". Monthly Notes of the Astronomical Society of South Africa. 26: 144. Bibcode: 1967MNSSA..26..144W. ISSN 0024-8266.
- ^ McInally, C. J.; Austin, R. D. (September 1977). "RS Cha: a delta Scuti Variable". Information Bulletin on Variable Stars. 1334: 1. Bibcode: 1977IBVS.1334....1M. ISSN 0374-0676.
- ^ Murphy, Simon J.; Lawson, Warrick A.; Bessell, Michael S. (20 August 2013). "Re-examining the membership and origin of the ϵ Cha association". Monthly Notices of the Royal Astronomical Society. 435 (2): 1325–1349. arXiv: 1305.4177. Bibcode: 2013MNRAS.435.1325M. doi: 10.1093/mnras/stt1375. eISSN 1365-2966. ISSN 0035-8711.