DH Cephei

Last updated
DH Cephei
SH2-142HunterWilson.jpg
DH Cephei is at the center of this image of the NGC 7380 complex [1]
Observation data
Epoch J2000.0        Equinox J2000.0
Constellation Cepheus
Right ascension 22h 46m 54.111s [2]
Declination +58° 05 03.53 [2]
Apparent magnitude  (V)8.61 [3] (8.63 – 8.70) [4]
Characteristics
Evolutionary stage Main sequence
Spectral type O5.5 V + O6 V [5]
B−V color index 0.334±0.041 [6]
Variable type Ellipsoidal [7] [4]
Astrometry
Radial velocity (Rv)−33.4±3.2 [6]  km/s
Proper motion (μ)RA: −2.599  mas/yr [2]
Dec.: −2.236  mas/yr [2]
Parallax (π)0.3397 ± 0.0138  mas [2]
Distance 9,600 ± 400  ly
(2,900 ± 100  pc)
Absolute magnitude  (MV)−4.66±0.25 (A)
−4.55±0.25 (B) [8]
Orbit [3]
Period (P)2.11095 d
Semi-major axis (a)≥9.79±0.17  R
Eccentricity (e)0.0 (fixed)
Periastron epoch (T)2,456,525.564±0.006 HJD
Details [3]
A
Mass 25.0 [9] or
38.4±2.5  M
Radius 8.31 [9]   R
Luminosity 2.34×105 [9]   L
Surface gravity (log g)4.3±0.3  cgs
Temperature 44,000  K
Rotational velocity (v sin i)175 km/s
B
Mass 16.8 [9] or
33.4±2.2  M
Radius 7.76 [9]   R
Luminosity1.86×105 [9]   L
Surface gravity (log g)4.3±0.2  cgs
Temperature 43,000  K
Rotational velocity (v sin i)160 km/s
Other designations
DH Cep, BD+57° 2607, HD  215835, HIP  112470, WDS 22469+5805 [1]
Database references
SIMBAD data

DH Cephei is a variable binary star [5] system in the northern circumpolar constellation of Cepheus, positioned about two degrees to the east of the star system Delta Cephei. [10] With an apparent visual magnitude of 8.61, [3] it is too faint to be visible without a telescope. Based on parallax measurements, this system is located at a distance of approximately 9.6 kilolight-years (2.9 kiloparsecs ) from the Sun. [2] At present it is moving closer to the Earth with a radial velocity of −33 km/s. [6]

A visual band light curve for DH Cephei, adapted from Lines et al. (1986) DHCepLightCurve.png
A visual band light curve for DH Cephei, adapted from Lines et al. (1986)

This is a double-lined spectroscopic binary system consisting of two near-identical, massive, O-type main sequence stars. [5] Evolutionary tracks place the stars close to the zero age main sequence, with an age of less than two million years. [12] This is a detached binary [12] with a close orbit having a period of 2.11 days, and the orbit is assumed to have circularized. The orbital plane is estimated to be inclined by an angle of 47°± to the line of sight from the Earth, which yields mass estimates of 38 and 34 times the mass of the Sun. [3]

In 1949, Joseph Algernon Pearce derived the orbital elements for DH Cephei (then known as HD 215835) and predicted that the binary pair would show eclipses, although he had no data to prove that. [13] Graham Hill et al. confirmed the predicted variability of star's brightness, in 1976. [14] Although initially suspected to be an eclipsing binary and given a variable star designation, [8] it doesn't appear to be eclipsing. [3] Instead, the system displays ellipsoidal light variations that are caused by tidal distortions. [7]

This system lies at the center of the young open cluster NGC 7380. It is the primary ionizing source for the surrounding H II region designated S142. The pair are a source of X-ray emission, which may be the result of colliding stellar winds. [15] Their measured X-ray luminosity is 3.2×1031 erg s−1. [9] The location and rare class of these stars make them an important object for astronomical studies. [8]

Related Research Articles

<span class="mw-page-title-main">Beta Lyrae</span> Multiple star system in the constellation of Lyra

Beta Lyrae officially named Sheliak, the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 960 light-years distant from the Sun.

<span class="mw-page-title-main">9 Andromedae</span> Star in the constellation Andromeda

9 Andromedae, abbreviated 9 And by convention, is a variable binary star system in the northern constellation Andromeda. 9 Andromedae is the Flamsteed designation, while it bears the variable star designation AN Andromedae, or AN And. The maximum apparent visual magnitude of the system is 5.98, which places it near the lower limit of visibility to the human eye. Based upon an annual parallax shift of 7.1 mas, it is located 460 light years from the 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.

<span class="mw-page-title-main">VV Cephei</span> Binary star in the constellation Cepheus

VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus. It is both a B[e] star and shell star. As a 5th magnitude star, it is visible to the naked eye under good observing conditions.

3 Centauri is a triple star system in the southern constellation of Centaurus, located approximately 300 light years from the Sun. It is visible to the naked eye as a faint, blue-white hued star with a combined apparent visual magnitude of 4.32. As of 2017, the two visible components had an angular separation of 7.851″ along a position angle of 106°. The system has the Bayer designation k Centauri; 3 Centauri is the Flamsteed designation. It was a suspected eclipsing binary with a variable star designation V983 Centauri, however the AAVSO website lists it as non-variable, formerly suspected to be variable.

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

DV Aquarii is a binary star system in the zodiac constellation of Aquarius, near the border with Capricornus. It has a peak apparent visual magnitude of 5.89, which is bright enough to be visible to the naked eye. The distance can be estimated from its annual parallax shift of 11.2 mas, yielding a separation of 291 light years.

<span class="mw-page-title-main">V1472 Aquilae</span> Binary star system in the constellation Aquila

V1472 Aquilae is a triple star system in the equatorial constellation of Aquila. It is a variable star that ranges in brightness from 6.36 down to 6.60. The system is located at a distance of approximately 780 light years from the Sun based on parallax. It is a high-velocity star system with a radial velocity of −112 km/s. When it is at its brightest, it is very faintly visible to the naked eye under excellent observing conditions.

<span class="mw-page-title-main">V381 Cephei</span> Triple star system in the constellation Cepheus

V381 Cephei is a triple star system in the northern constellation of Cepheus. Its apparent magnitude is slightly variable between 5.5 and 5.7.

HD 106515 is a binary star in the constellation of Virgo.

<span class="mw-page-title-main">HD 37756</span> Binary star system in the constellation Orion

HD 37756 is a binary star system in the equatorial constellation of Orion, positioned less than a degree to the north of the bright star Alnitak. It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.95. The system is located at a distance of approximately 900 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +26 km/s. It is a member of the OB1b subgroup of the Orion OB1 association.

<span class="mw-page-title-main">QZ Puppis</span> Star in the constellation Puppis

QZ Puppis is a class B2.5V star in the constellation Puppis. Its apparent magnitude is 4.5 and it is approximately 650 light years away based on parallax.

<span class="mw-page-title-main">14 Lacertae</span> Binary star in the constellation Lacerta

14 Lacertae is a binary star system in the northern constellation Lacerta, located around 1,600 light years away. It has the variable star designation V360 Lacertae; 14 Lacertae is the Flamsteed designation. The system is barely visible to the naked eye in good seeing conditions, having a peak apparent visual magnitude of 5.91. It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.

Chi<sup>2</sup> Hydrae Binary star system in the constellation Hydra

Chi2 Hydrae, Latinised from χ2 Hydrae, is a binary star system in the equatorial constellation of Hydra. Based upon an annual parallax shift of 4.6 mas as seen from Earth, it is located roughly 685 light years from the Sun. It is visible to the naked eye with a combined apparent visual magnitude of about 5.7.

<span class="mw-page-title-main">31 Cygni</span> Triple star system in the constellation Cygnus

31 Cygni, also known as ο1 Cygni, Omicron1 Cygni, ο2 Cygni or V695 Cygni, is a ternary star system about 750 light years away in the constellation Cygnus.

<span class="mw-page-title-main">AC Herculis</span> Spectroscopic binary star in the constellation Hercules

AC Herculis, is an RV Tauri variable and spectroscopic binary star in the constellation of Hercules. It varies in brightness between apparent magnitudes 6.85 and 9.0.

<span class="mw-page-title-main">16 Lacertae</span> Triple star system in the constellation Lacerta

16 Lacertae is a triple star system in the northern constellation of Lacerta, located about 1,580 light years from the Sun. It has the variable star designation EN Lacertae; 16 Lacertae is the Flamsteed designation. This system is visible to the naked eye as a faint blue-white hued star with a maximum apparent visual magnitude of +5.587. It is moving closer to the Earth with a heliocentric radial velocity of –12 km/s.

Psi<sup>2</sup> Orionis Spectroscopic binary system in the constellation of Orion

Psi2 Orionis a binary star system in the equatorial constellation of Orion. It has an apparent visual magnitude of 4.6, indicating that it is visible to the naked eye. Based upon an annual parallax shift of 2.87 mass, it is roughly 1,100 light years distant from the Sun.

<span class="mw-page-title-main">U Lacertae</span> Binary star in the constellation Lacerta

U Lacertae is a spectroscopic binary star in the constellation Lacerta.

<span class="mw-page-title-main">RS Sagittarii</span> Eclipsing binary star system in the constellation Sagittarius

RS Sagittarii is an eclipsing binary star system in the southern constellation of Sagittarius, abbreviated RS Sgr. It is a double-lined spectroscopic binary with an orbital period of 2.416 days, indicating that the components are too close to each other to be individually resolved. The system has a combined apparent visual magnitude of 6.01, which is bright enough to be faintly visible to the naked eye. During the primary eclipse the brightness drops to magnitude 6.97, while the secondary eclipse is of magnitude 6.28. The distance to this system is approximately 1,420 light years based on parallax measurements.

<span class="mw-page-title-main">WY Geminorum</span> Binary star in the constellation Gemini

WY Geminorum is a binary star system in the northern constellation of Gemini, abbreviated WY Gem. It has an apparent visual magnitude that ranges from 7.26 down to 7.51, which is too faint to be readily viewed with the naked eye. This system is located at a distance of approximately 6,300 light years from the Sun based on parallax measurements, and is receding with a radial velocity of 19.5 km/s.

References

  1. 1 2 "HD 215835". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-10-20.{{cite web}}: CS1 maint: postscript (link)
  2. 1 2 3 4 5 6 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.
  3. 1 2 3 4 5 6 Martins, F.; et al. (November 2017), "Properties of six short-period massive binaries: A study of the effects of binarity on surface chemical abundances", Astronomy & Astrophysics, 607: 13, arXiv: 1709.00937 , Bibcode:2017A&A...607A..82M, doi:10.1051/0004-6361/201731593, S2CID   7835895, A82.
  4. 1 2 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports , 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  5. 1 2 3 Sota, A.; et al. (March 2014), "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars", The Astrophysical Journal Supplement, 211 (1): 84, arXiv: 1312.6222 , Bibcode:2014ApJS..211...10S, doi:10.1088/0067-0049/211/1/10, S2CID   118847528, 10.
  6. 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971 , Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID   119257644.
  7. 1 2 Penny, Laura R.; et al. (July 1997), "Tomographic Separation of Composite Spectra. IV. The Physical Properties of the Massive Close Binary DH Cephei", The Astrophysical Journal, 483 (1): 439–448, Bibcode:1997ApJ...483..439P, doi: 10.1086/304239 .
  8. 1 2 3 Hilditch, R. W.; et al. (October 1996), "New masses for the O-type binary DH Cephei, and the temperatures of O-stars.", Astronomy and Astrophysics, 314: 165–172, Bibcode:1996A&A...314..165H.
  9. 1 2 3 4 5 6 7 Krtička, J.; et al. (July 2015), "X-ray irradiation of the winds in binaries with massive components", Astronomy & Astrophysics, 579: 15, arXiv: 1505.03411 , Bibcode:2015A&A...579A.111K, doi:10.1051/0004-6361/201525637, S2CID   119120927, A111.
  10. Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas, vol. 3, Sky Publishing Corporation and the European Space Agency, p. 1071, ISBN   0-933346-84-0.
  11. Lines, L. C.; Lines, R. D.; Guinan, E. F.; Robinson, C. R. (September 1986), "B and V Light Curves of the Massive Close Binary DH Cephei", Information Bulletin on Variable Stars, 2932: 1, Bibcode:1986IBVS.2932....1L , retrieved 1 January 2022.
  12. 1 2 Sturm, E.; Simon, K. P. (February 1994), "Spectroscopic analysis of hot binaries. I. The components of DH Cephei", Astronomy and Astrophysics, 282: 93–105, Bibcode:1994A&A...282...93S.
  13. Pearce, J. A. (April 1949). "HD 215835 - a new massive eclipsing system". Astronomical Journal. 54: 135–136. Bibcode:1949AJ.....54..135P. doi:10.1086/106226 . Retrieved 20 January 2025.
  14. Hill, G.; Hilditch, R. W.; Pfannenschmidt, E. L. (1976). "Photoelectric measures of variable stars observed at Mt. Kobau (1970 - 73)". Publications of the Dominion Astrophysical Observatory Victoria. 15: 1–35. Bibcode:1976PDAO...15....1H . Retrieved 20 January 2025.
  15. Lata, Sneh; et al. (March 2016), "Variable stars in young open star cluster NGC 7380", Monthly Notices of the Royal Astronomical Society, 456 (3): 2505–2517, arXiv: 1511.08892 , Bibcode:2016MNRAS.456.2505L, doi: 10.1093/mnras/stv2800 , S2CID   118473907.