Epsilon Lyrae: Difference between revisions

Epsilon Lyrae
	; ε (circled) in the constellation Lyra.
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Lyra
	Epsilon1 Lyrae
Right ascension	18h 44m 20.34589s
Declination	+39° 40′ 12.4533″
Apparent magnitude (V)	4.7
	Epsilon2 Lyrae
Right ascension	18h 44m 22.78056s
Declination	+39° 36′ 45.7851″
Apparent magnitude (V)	5.1
Characteristics
ε1 Lyr
Spectral type	A3V + F0V
U−B color index	+0.065
B−V color index	+0.16
ε2 Lyr
Spectral type	A6Vn + A7Vn
U−B color index	+0.075
B−V color index	+0.18
Astrometry
ε1 Lyr
Radial velocity (Rv)	−31.20 ± 1.7 km/s
Proper motion (μ)	RA: 11.09 mas/yr ; Dec.: 61.39 mas/yr
Parallax (π)	20.10 ± 0.76 mas
Distance	162 ± 6 ly ; (50 ± 2 pc)
ε2 Lyr
Radial velocity (Rv)	−24.40 ± 1.7 km/s
Proper motion (μ)	RA: 6.18 mas/yr ; Dec.: 50.42 mas/yr
Parallax (π)	20.97 ± 0.50 mas
Distance	156 ± 4 ly ; (48 ± 1 pc)
Other designations
	4 Lyr, ADS 11635, BD +39 03509, HIP 91919, WDS 18443+3940.
	ε1 Lyr: HD 173582, HR 7051, SAO 67310.
	ε2 Lyr: HD 173583, HR 7052, SAO 67309
Database references
SIMBAD	ε1 Lyr
	ε2 Lyr

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Revision as of 20:06, 11 March 2017

Epsilon Lyrae (ε Lyr, ε Lyrae), also known as the Double Double, is a multiple star system approximately 162 light-years away in the constellation of Lyra.

Star System

The widest two components of the system are easily separated when viewed through binoculars, or even with the naked eye under excellent conditions.^[6] The northern component is called ε¹ and the southern one is called ε²; they both lie around 162 light years from Earth and orbit each other. When viewed at higher magnifications, both stars of the binary can be further split into binaries; that is, the system contains two sets of binary stars orbiting each other. Being able to view the components of each is a common benchmark for the resolving power of telescopes, since the individual doubles are so close together: the stars of ε¹ were 2.35 arc-seconds apart in 2006, those of ε² were separated by about the same amount in that year. Since the first high-precision measurements of their orbit in the 1980s, both binaries have moved only a few degrees in position angle.

The component stars of ε¹ have magnitudes of 4.7 and 6.2 separated by 2.6" and have an orbital period that can only be crudely estimated at 1200 years, which places them at roughly 140 AU apart. The component stars of ε² have magnitudes 5.1 and 5.5 separated by 2.3", and orbit in perhaps half that period. ε¹ and ε² themselves are not closer than 0.16 light years apart, and would take hundreds of thousands of years to complete an orbit. An observer at one pair would see the other pair shining with the light of a quarter Moon (which is about mv = −5.0), less than a degree away from each other.^[7]^[8]

A fifth component of this system, orbiting one of the ε² pair, was detected by speckle interferometry in 1985 and confirmed in two subsequent observations. No orbit can be prepared from such limited data, but its rapid motion suggests a period of a few tens of years. Its maximum observed separation of 0.2 arc-seconds precludes direct visual observation.

A number of other nearby stars may also be part of the system, bringing the system to a total of ten stars. The arrangement of the system is summarised in the tables below.

Stars in the system
	Magnitude	Spectral Type
A	5.02	A2
B	6.02	A4
C	5.14	A3
D	5.37	A5
E	11.71
F	11.2
G	13.83
H	13.22
I	10.43
a	10.43

^[6]^[9]

Orbit pairs
	Separation (arcsec)	Separation (au)	Most Recent Position Angle	Period (years)	Semi-major axis (arcseconds)	Notes
AB-CD	208.2	10,500	172			ε¹-ε²
AB	2.3	116	347	1804.41	4.742	components of ε¹
CD	2.4	121	79	724.307	2.92	components of ε²
Ca	0.1	5	225			recently discovered interferometric companion
AI	149.6	7500	138
CE	63.7	3200	333
EF	46	2300	37
EG	50	2500	238
GH	35	1800	358

^[6]^[9]^[10]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
^ ^a ^b Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 95: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
^ ^a ^b ^c ^d Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Bibcode:1986EgUBV........0M. {{cite journal}}: Cite journal requires |journal= (help)
^ Gontcharov, G. A. (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. Retrieved 12 December 2016.
^ Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776.
^ ^a ^b ^c Burnham, Robert (1966). Burnham's Celestial Handbook. Dover Publications Inc. pp. 1151–1153. ISBN 0-486-24064-9.
^ Jim Kaler. "Epsilon Lyrae". Kaler's Stars. Retrieved 18 November 2013.
^ http://observing.skyhound.com/archives/jul/HR_7051.html
^ ^a ^b "Washington Double Star Catalog". Retrieved 19 December 2010.
^ "Sixth Orbit Catalog". Retrieved 19 December 2010.

External links

[HIP-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.

[Abt-2] Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 95: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.

[EgUBV-3] Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Bibcode:1986EgUBV........0M. {{cite journal}}: Cite journal requires |journal= (help)

[RV-4] Gontcharov, G. A. (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. Retrieved 12 December 2016.

[5] Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776.

[Burnhams-6] Burnham, Robert (1966). Burnham's Celestial Handbook. Dover Publications Inc. pp. 1151–1153. ISBN 0-486-24064-9.

[7] Jim Kaler. "Epsilon Lyrae". Kaler's Stars. Retrieved 18 November 2013.

[8] ttp://observing.skyhound.com/archives/jul/HR_7051.html

[wds-9] "Washington Double Star Catalog". Retrieved 19 December 2010.

[10] "Sixth Orbit Catalog". Retrieved 19 December 2010.

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@@ Line 19: / Line 19: @@
  | constell = [[Lyra]]
  | component1 = Epsilon<sup>1</sup> Lyrae
+ | ra1 = {{RA|18|44|20.34589}}<ref name=HIP>{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author1=van Leeuwen, F.|display-authors=etal|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357}}</ref>
- | ra1 = {{RA|18|44|20.3453}}
- | dec1 = {{DEC|+39|40|12.444}}
+ | dec1 = {{DEC|+39|40|12.4533}}<ref name=HIP/>
  | appmag_v1 = 4.7
  | component2 = Epsilon<sup>2</sup> Lyrae
- | ra2 = {{RA|18|44|22.7803}}
+ | ra2 = {{RA|18|44|22.78056}}<ref name=HIP/>
- | dec2 = {{DEC|+39|36|45.798}}
+ | dec2 = {{DEC|+39|36|45.7851}}<ref name=HIP/>
  | appmag_v2 = 5.1
 }}
 {{Starbox character
+ | component = ε<sup>1</sup> Lyr
- | class = F1V + A8V
+ | class = A3V + F0V<ref name=Abt>{{cite journal|title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars|author1=Abt, Helmut A.|author2=Morrell, Nidia I.|journal=Astrophysical Journal Supplement|volume=95|page=135|date=1995|bibcode=1995ApJS...99..135A|doi=10.1086/192182}}</ref>
- | r-i = <!--R-I color-->
- | v-r = <!--V-R color-->
+ | b-v = +0.16<ref name=EgUBV/>
- | b-v = <!--B-V color-->
+ | u-b = +0.065<ref name=EgUBV/>
- | u-b = <!--U-B color-->
+ | variable = <!--Variability type-->
+}}
+{{Starbox character|no_heading=y
+ | component = ε<sup>2</sup> Lyr
+ | class = A6Vn + A7Vn<ref name=Abt/>
+ | b-v = +0.18<ref name=EgUBV>{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M}}</ref>
+ | u-b = +0.075<ref name=EgUBV/>
  | variable = <!--Variability type-->
 }}
 {{Starbox astrometry
+ | component1 = ε<sup>1</sup> Lyr
- | radial_v = <!--Radial velocity (in km/sec)-->
+ | radial_v = −31.20 ± 1.7<ref name=RV>{{cite journal|url=http://adsabs.harvard.edu/abs/2006AstL...32..759G|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|author=Gontcharov, G. A.|date=2006|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|bibcode=2006AstL...32..759G|doi=10.1134/S1063773706110065|arxiv=1606.08053|accessdate=12 December 2016}}</ref>
- | prop_mo_ra = <!--Proper motion (RA), μα cos δ (in milliarcsec/yr)-->
+ | prop_mo_ra = 11.09<ref name=HIP/>
- | prop_mo_dec = <!--Proper motion (dec), μδ (in milliarcsec/yr)-->
+ | prop_mo_dec = 61.39<ref name=HIP/>
  | parallax = 20.10
  | p_error = 0.76
- | parallax_footnote = <!--Parallax footnote-->
+ | parallax_footnote = <ref name=HIP/>
+ | component2 = ε<sup>2</sup> Lyr
- | dist_ly = <!--Distance (in light years)-->
+ | radial_v2 = −24.40 ± 1.7<ref>{{cite journal|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations|author1=Kharchenko, N. V.|display-authors=etal|journal=Astronomische Nachrichten|volume=328|issue=9|page=889|date=2007|bibcode=2007AN....328..889K|doi=10.1002/asna.200710776|arxiv=0705.0878}}</ref>
- | dist_pc = <!--Distance (in parsecs)-->
+ | prop_mo_ra2 = 6.18<ref name=HIP/>
- | space_v_u = <!--Space velocity (U), σu cos v w (in km/s)-->
+ | prop_mo_dec2 = 50.42<ref name=HIP/>
- | space_v_v = <!--Space velocity (V), σv cos w (in km/s)-->
+ | parallax2 = 20.97
- | space_v_w = <!--Space velocity (W), σw (in km/s)-->
+ | p_error2 = 0.50
- | absmag_v = <!--Absolute magnitude (Johnson-Cousins V system)-->
+ | parallax_footnote2 = <ref name=HIP/>
-}}
-{{Starbox catalog
- | names = 4 Lyr,
 }}
 {{Starbox catalog
  | names      = 4 Lyr, ADS 11635, [[Bonner Durchmusterung|BD]] +39 03509, [[Hipparcos catalogue|HIP]] 91919, [[Washington Double Star Catalog|WDS]] 18443+3940.
  | component1 = ε<sup>1</sup> Lyr
- | names1     = [[Henry Draper catalogue|HD]] 173582, [[Harvard Revised catalogue|HR]] 7051, SAO 67310.
+ | names1     = [[Henry Draper catalogue|HD]] 173582, [[Harvard Revised catalogue|HR]] 7051, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 67310.
  | component2 = ε<sup>2</sup> Lyr
- | names2     = HD 173583, HR 7052, SAO 67309.
+ | names2     = HD 173583, HR 7052, SAO 67309
-}}
-{{Starbox reference
-| Simbad = eps01+Lyr
-| ARICNS = <!--Code-->
 }}
 {{Starbox reference
-| Simbad = eps02+Lyr
+| Simbad = eps01+Lyr|sn=ε<sup>1</sup> Lyr
+| Simbad2 = eps02+Lyr|sn2=ε<sup>2</sup> Lyr
-| ARICNS = <!--Code-->
 }}
 {{Starbox end}}

Observation data Epoch J2000.0 Equinox J2000.0
ε (circled) in the constellation Lyra.
Constellation	Lyra
Epsilon¹ Lyrae
Right ascension	18^h 44^m 20.34589^s^[1]
Declination	+39° 40′ 12.4533″^[1]
Apparent magnitude (V)	4.7
Epsilon² Lyrae
Right ascension	18^h 44^m 22.78056^s^[1]
Declination	+39° 36′ 45.7851″^[1]
Apparent magnitude (V)	5.1
Characteristics
ε¹ Lyr
Spectral type	A3V + F0V^[2]
U−B color index	+0.065^[3]
B−V color index	+0.16^[3]

ε² Lyr
Spectral type	A6Vn + A7Vn^[2]
U−B color index	+0.075^[3]
B−V color index	+0.18^[3]
Astrometry
ε¹ Lyr
Radial velocity (R_v)	−31.20 ± 1.7^[4] km/s
Proper motion (μ)	RA: 11.09^[1] mas/yr Dec.: 61.39^[1] mas/yr
Parallax (π)	20.10 ± 0.76 mas^[1]
Distance	162 ± 6 ly (50 ± 2 pc)
ε² Lyr
Radial velocity (R_v)	−24.40 ± 1.7^[5] km/s
Proper motion (μ)	RA: 6.18^[1] mas/yr Dec.: 50.42^[1] mas/yr
Parallax (π)	20.97 ± 0.50 mas^[1]
Distance	156 ± 4 ly (48 ± 1 pc)
Other designations
4 Lyr, ADS 11635, BD +39 03509, HIP 91919, WDS 18443+3940.
ε¹ Lyr: HD 173582, HR 7051, SAO 67310.
ε² Lyr: HD 173583, HR 7052, SAO 67309
Database references
SIMBAD	ε¹ Lyr
	ε² Lyr

Revision as of 20:06, 11 March 2017

Star System

See also

References

External links