HU Aquarii

Last updated
HU Aquarii
HUAqrLightCurve.png
The visual band light curve of HU Aquarii, adapted from Shengbang et al. (2016) [1]
Observation data
Epoch J2000        Equinox J2000
Constellation Aquarius
Right ascension 21h 07m 58.19445s [2]
Declination −05° 17′ 40.5577″ [2]
Apparent magnitude  (V)+15.3
Characteristics
Spectral type DAm / M4.5V
Variable type AM Herculis
Astrometry
Proper motion (μ)RA: -64.579 [2]   mas/yr
Dec.: -62.732 [2]   mas/yr
Parallax (π)5.2354 ± 0.0457  mas [2]
Distance 623 ± 5  ly
(191 ± 2  pc)
Details
Mass 0.88/0.2  M☉
Radius 0.01/0.22  R☉
Luminosity 0.0022/0.0052  L☉
Temperature 12,500/3,400  K
Orbit
Period (P)2.08 hours [3]
Semi-major axis (a)0.0032 au
Eccentricity (e)0.0
Inclination (i)85°
Other designations
HU Aqr, RBS 1724, RE J210755-051621, 1RXS J210758.5-051744, 1AXG J210759-0518, 2RE J210755-051630, RE J2107-051, EUVE J2108-05.2, 2RE J2107-051, RX J2107.9-0518, AAVSO 2102-05, GSC 05200-00849, RE J2107-05, RX J2107.9-0517, 2MASS J21075818-0517404, Gaia DR2 6911950900211768704 [4]
Database references
SIMBAD data

HU Aquarii (abbreviated HU Aqr) is an eclipsing binary system approximately 620 light-years away from the Sun, [2] forming a cataclysmic variable of AM Herculis-type. The two stars orbit each other every 2.08 hours [3] and the ultra-short binary system includes an eclipsing white dwarf and red dwarf.

Contents

Eclipse timing variations

The HU Aquarii binary system exhibits variations in the timing of the eclipses. Schwarz et al. (2009) note that the variations are too large to be caused by the Applegate mechanism, and are within the expected range of magnetic braking but 30 times too large to be caused by gravitational radiation alone. As an alternative explanation, they suggested that the variations might be caused by an object in orbit around the binary, causing it to move back and forth along the line-of-sight to the system. [5] In March 2011, Qian et al. claimed the presence of two planets, [6] though the proposed orbits were subsequently shown to be unstable [7] and on orbits determined from a more thorough and precise analysis of the observational data. [8] Indeed, it seems likely that the signal that was interpreted as being the result of planetary companions might be instead the result of not well-studied interactions between the white dwarf and its red dwarf companion: as of 2014 all proposed orbital solutions have been refuted and it appears that the full set of timing measurements is inconsistent with any 1, 2 or 3-planet system due to poor fits to the data and unstable orbital configurations. [9] With new data gathered by 2018, the existence of planetary system remains elusive, as no model fitting all observations can be made. [10]

See also

Related Research Articles

<span class="mw-page-title-main">Xi Aquarii</span> Star in the constellation Aquarius

Xi Aquarii is a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.7. Based upon parallax measurements made during the Hipparcos mission, this system lies at a distance of around 179 light-years from the Sun.

<span class="mw-page-title-main">Zeta Aquarii</span> Triple star system in constellation of Aquarius

Zeta Aquarii is the Bayer designation for a triple star system, the central star of the "water jar" asterism in the equatorial constellation of Aquarius. The combined apparent visual magnitude of this system is 3.65, which is readily visible to the naked eye. Parallax measurements yield a distance estimate of around 92 light-years from Earth.

<span class="mw-page-title-main">91 Aquarii</span> Triple star system in the constellation Aquarius

91 Aquarii is the Flamsteed designation for a triple star system in the equatorial constellation of Aquarius. It also bears the Bayer designation Psi1 Aquarii. It is visible to the naked eye with an apparent visual magnitude of +4.248. Parallax measurements yield an estimated distance of around 150 light-years from Earth. An extrasolar planet is known to orbit the main star.

<span class="mw-page-title-main">Mu Aquarii</span> Binary star system in the constellation Aquarius

Mu Aquarii, Latinized from μ Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with a combined apparent visual magnitude of 4.7. Based upon parallax measurements, the distance to this system is about 157 light-years. It is drifting closer to the Sun with a radial velocity of −9.1 km/s.

<span class="mw-page-title-main">Sigma Aquarii</span> Star in the constellation Aquarius

Sigma Aquarii, Latinized from σ Aquarii, is a double star in the equatorial constellation of Aquarius, positioned about 1.3° to the south of the ecliptic. Due to its proximity to the ecliptic, this star is subject to occultation by the Moon. It has a white hue and is visible to the naked eye with an apparent visual magnitude of 4.81. Based upon parallax measurements, the distance to this star is approximately 175 light-years. It is drifting further away with a radial velocity of +11 km/s.

<span class="mw-page-title-main">Upsilon Aquarii</span> Star in the constellation Aquarius

Upsilon Aquarii, Latinized from υ Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.21. Parallax measurements give a distance estimate of 74.8 light-years from Earth. This is a high proper-motion star that is drifting closer to the Sun with a radial velocity of –2.3 km/s. It is part of the Hercules-Lyra association.

94 Aquarii is a triple star system in the equatorial constellation of Aquarius. 94 Aquarii is the Flamsteed designation. The brightest member has an apparent visual magnitude of 5.19, making it visible to the naked eye. The parallax measured by the Gaia spacecraft yields a distance estimate of around 73 light-years from Earth.

<span class="mw-page-title-main">29 Aquarii</span> Binary star in the constellation Aquarius

29 Aquarii is a binary star system located around 590 light years away from the Sun in the equatorial constellation of Aquarius. 29 Aquarii is the Flamsteed designation; the system also bears the variable star designation DX Aquarii. It is a challenge to view with the naked eye, appearing as a dim star with a combined apparent visual magnitude of 6.39. The system is moving further from the Earth with a heliocentric radial velocity of about +15 km/s.

58 Aquarii, abbreviated 58 Aqr, is a star in the constellation of Aquarius. 58 Aquarii is its Flamsteed designation. It is a sixth magnitude star with an apparent visual magnitude of 6.39, which means it is a challenge to view with the naked eye. Based upon an annual parallax shift of 13.4 mas, it is located 243 light years from the Sun. This has been identified as a visual binary system with an orbital period of 829.976 days in a circular orbit.

<span class="mw-page-title-main">HW Virginis</span> Eclipsing binary star in the constellation Virgo

HW Virginis, abbreviated HW Vir, is an eclipsing binary system, approximately 563 light-years away based on the parallax measured by the Gaia spacecraft, in the constellation of Virgo. The system comprises an eclipsing B-type subdwarf star and red dwarf star. The two stars orbit each other every 0.116795 days.

<span class="mw-page-title-main">Circumbinary planet</span> Planet that orbits two stars instead of one

A circumbinary planet is a planet that orbits two stars instead of one. The two stars orbit each other in a binary system, while the planet typically orbits farther from the center of the system than either of the two stars. In contrast, circumstellar planets in a binary system have stable orbits around one of the two stars, closer in than the orbital distance of the other star. Studies in 2013 showed that there is a strong hint that a circumbinary planet and its stars originate from a single disk.

<span class="mw-page-title-main">NN Serpentis</span> Eclipsing post-common envelope binary star system in the constellation Serpens

NN Serpentis is an eclipsing post-common envelope binary system approximately 1670 light-years away. The system comprises an eclipsing white dwarf and red dwarf. The two stars orbit each other every 0.13 days.

<span class="mw-page-title-main">Y Sextantis</span> Variable star in the constellation Sextans

Y Sextantis, abbreviated as Y Sex, is a variable star system in the equatorial constellation of Sextans. The system is invisible to the naked eye with a mean apparent visual magnitude of 9.88. It is located roughly at 1,300 light years from the Sun based on parallax.

<span class="mw-page-title-main">QS Virginis</span> Eclipsing binary star in the constellation Virgo

QS Virginis is an eclipsing binary system approximately 163 light-years away from the Sun, forming a cataclysmic variable. The system comprises an eclipsing white dwarf and red dwarf that orbit each other every 3.37 hours.

<span class="mw-page-title-main">DP Leonis</span> Star system in the constellation Leo

DP Leonis is a binary star system in the equatorial constellation of Leo. It is a variable star that ranges in apparent visual magnitude from 17.5 down to 19. The system is located at a distance of approximately 990 light-years from the Sun based on parallax. It is a cataclysmic variable star of the AM Herculis-type also known as polars. The system comprises an eclipsing white dwarf and red dwarf in tight orbit and an extrasolar planet. This eclipsing variable was discovered by P. Biermann and associates in 1982 as the optical counterpart to the EINSTEIN X-ray source E1114+182.

<span class="mw-page-title-main">RR Caeli</span> Double star in the constellation Caelum

RR Caeli is an eclipsing binary star in the constellation Caelum. It is 69 light years from Earth.

<span class="mw-page-title-main">NSVS 14256825</span> Eclipsing binary star in the constellation Aquila

NSVS 14256825, also known as V1828 Aquilae, is an eclipsing binary system in the constellation of Aquila. The system comprises a subdwarf OB star and red dwarf star. The two stars orbit each other every 2.648976 hours. Based on the stellar parallax of the system, observed by Gaia, the system is located approximately 2,700 light-years away.

<span class="mw-page-title-main">UZ Fornacis</span> Binary star system in the constellation Fornax

UZ Fornacis is a binary star in the constellation of Fornax. It appears exceedingly faint with a maximum apparent magnitude 17.0. Its distance, as measured by Gaia using the parallax method, is about 780 light-years.

<span class="mw-page-title-main">NY Virginis</span> Binary star in the constellation Virgo

NY Virginis is a binary star about 1,940 light-years away. The primary belongs to the rare class of subdwarf B stars, being former red giants with their hydrogen envelope completely stripped by a stellar companion. The companion is a red dwarf star. The binary nature of NY Virginis was first identified in 1998, and the extremely short orbital period of 0.101016 d, together with brightness variability on the timescale of 200 seconds was noticed, resulting in the identification of the primary star as a B-type subdwarf in 2003. Under a proposed classification scheme for hot subdwarfs it would be class sdB1VII:He1. This non-standard system indicates that it is a "normal" luminosity for a hot subdwarf and that the spectrum is dominated by hydrogen rather than helium.

<span class="mw-page-title-main">EQ Tauri</span>

EQ Tauri is a triple star system in the equatorial constellation of Taurus that includes a contact eclipsing binary. The system is too faint to be viewed with the naked eye, having a baseline apparent visual magnitude of 10.5. During the primary eclipse, the brightness of the system drops to magnitude 11.03, then to 10.97 during the secondary minimum. The secondary eclipse is total. Based on parallax measurements, it is located at a distance of approximately 730 light years from the Sun.

References

  1. ↑ Shengbang, Qian; Zhongtao, Han; Fernández Lajús, E; liying, Zhu; Wenping, Liao; Miloslav, Zejda; Linjia, Li; Voloshina, Irina; Liang, Liu; Jiajia, He (July 2016). "Interactions between planets and evolved stars". Journal of Physics: Conference Series. 728 (4): 042006. Bibcode:2016JPhCS.728d2006S. doi: 10.1088/1742-6596/728/4/042006 . S2CID   125620672.
  2. 1 2 3 4 5 6 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.
  3. 1 2 Howell; et al. (2002). "An Exploration of the Paradigm for the 2-3 Hour Period Gap in Cataclysmic Variables". The Astrophysical Journal . 550 (2): 897–918. arXiv: astro-ph/0005435 . Bibcode:2002MNRAS.336.1129B. doi:10.1046/j.1365-8711.2002.05841.x. S2CID   609324.
  4. ↑ V* HU Aqr -- CV of AM Her type (polar)
  5. ↑ Schwarz; et al. (2009). "Hunting high and low: XMM monitoring of the eclipsing polar HU Aquarii". Astronomy and Astrophysics . 496 (3): 833–840. arXiv: 0901.4902 . Bibcode:2009A&A...496..833S. doi:10.1051/0004-6361/200811485. S2CID   14243402.
  6. ↑ Qian, S.-B.; Liu, L.; Liao, W.-P.; Li, L.-J.; Zhu, L.-Y.; Dai, Z.-B.; He, J.-J.; Zhao, E.-G.; Zhang, J.; Li, K. (2011). "Detection of a planetary system orbiting the eclipsing polar HU Aqr". Monthly Notices of the Royal Astronomical Society. 414 (1): L16–L20. arXiv: 1103.2005 . Bibcode:2011MNRAS.414L..16Q. doi:10.1111/j.1745-3933.2011.01045.x. S2CID   119165158.
  7. ↑ Horner, Jonathan; Marshall, J. P.; Wittenmyer, Robert A.; Tinney, C. G. (September 2011). "A dynamical analysis of the proposed HU Aquarii planetary system". Monthly Notices of the Royal Astronomical Society: Letters . 416 (1): L11–L15. arXiv: 1106.0777 . Bibcode:2011MNRAS.416L..11H. doi:10.1111/j.1745-3933.2011.01087.x. S2CID   59135141.
  8. ↑ Wittenmyer, Robert; Horner, J.; Marshall, J. P.; Butters, O. W.; Tinney, C. G. (February 2012). "Revisiting the proposed planetary system orbiting the eclipsing polar HU Aquarii". Monthly Notices of the Royal Astronomical Society. 419 (4): 3258–3267. arXiv: 1110.2542 . Bibcode:2012MNRAS.419.3258W. doi:10.1111/j.1365-2966.2011.19966.x. S2CID   49524325.
  9. ↑ M. Bours; T. Marsh; E. Breedt; C. Copperwheat; V. Dhillon; A. Leckngam; S. Littlefair; S. Parsons; A. Prasit (2014). "Testing the planetary models of HU Aquarii". Monthly Notices of the Royal Astronomical Society. 445 (2): 1924–1931. arXiv: 1409.3586 . Bibcode:2014MNRAS.445.1924B. doi:10.1093/mnras/stu1879. S2CID   53630677.
  10. ↑ Schwope, A. D.; Thinius, B. D. (2018), "On the ephemeris of the eclipsing polar HU Aquarii. II: New eclipse epochs obtained 2014–2018", Astronomische Nachrichten, 339 (7–8): 540–544, arXiv: 1810.12886 , Bibcode:2018AN....339..540S, doi:10.1002/asna.201813526, S2CID   96446931

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.