| 词条 | 19 Draconis |
| 释义 |
|epoch=J2000 |constell=Draco |ra={{RA|16|56|01.68925}}[1] |dec={{DEC|+65|08|05.2631}}[1] |appmag_v=4.89[3] }}{{Starbox character |class=F8V[2] |b-v=+0.485[3] |u-b=-0.03[3] |variable= }}{{Starbox astrometry |radial_v=−21.00 ± 0.8[4] |prop_mo_ra=237.79[1] |prop_mo_dec=50.84[1] |parallax=65.54 |p_error=0.33 |parallax_footnote=[1] |absmag_v=3.98[11] }}{{Starbox orbit |reference=[5] |period_unitless=52.1089 ± 0.0001 d |axis_unitless=20.0 mas |inclination=90.5 ± 2.2 |node=23.5 ± 2.0 |periastron=JD 2453427.880 ± 0.007 |eccentricity=0.2221 ± 0.0002 |periarg=338.46 ± 0.05 |k1=17.465 ± 0.004 }}{{Starbox detail |source=[5] |component1=19 Dra A |mass=1.04 |radius=1.2 |temperature=6298 ± 80 |luminosity=2.02 |metal=Z {{=}} 0.013 ± 0.004 |rotational_velocity= |age_gyr=4.7 |component2=19 Dra B |mass2=0.37 |luminosity2=0.02 |radius2=0.3 }}{{Starbox catalog |names={{odlist|BD=+65° 1157|GJ=648|HD=153597|HIP=82860|HR=6315|SAO=17281}} }}{{Starbox reference |Simbad=19+Dra |ARICNS=01349 }}{{Starbox end}}19 Draconis, also known as h Draconis, is a star system in the constellation Draco. It is visible to the naked eye as a faint, yellow-white hued star with an apparent visual magnitude of 4.89.[3] Based on its parallax, the system is located about 49.8 light-years (15.26 parsecs) away.[1] It is moving closer to the Earth with a heliocentric radial velocity of −21 km/s.[4] This is a binary star system with an orbital period of 52.1 days and an eccentricity of 0.22. Only the primary star can be directly detected, via Doppler shifts or perturbations around the system's barycenter. Using spectroscopy and astrometry, the nature of the secondary star can be inferred. The primary star is an F-type main-sequence star with a stellar classification of F8V,[2] 4% more massive than the Sun. Its surface temperature is about 6,298 K, and it emits just over twice the amount of energy that the Sun does. The secondary is only 37% as massive as the Sun, and its luminosity is only 2% that of the Sun. The system is about 4.7 billion years old.[5] References1. ^1 2 3 4 5 {{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|author=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}} {{Stars of Draco}}2. ^1 {{cite journal|last=Abt, Helmut A.|date=2009|title=MK Classifications of Spectroscopic Binaries|journal=The Astrophysical Journal Supplement|volume=180|issue=1|pages=117–18|doi=10.1088/0067-0049/180/1/117 |bibcode=2009ApJS..180..117A}} 3. ^1 2 3 {{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV data|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M}} 4. ^1 {{cite journal|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}} 5. ^1 2 3 {{cite journal|bibcode=2015AJ....150..110W|doi=10.1088/0004-6256/150/4/110|title=Self-Consistent Orbits and Physical Properties for Eight Single-Lined Spectroscopic Binaries|journal=The Astronomical Journal|volume=150|issue=4|pages=110|year=2015|last1=Wang|first1=Xiaoli|last2=Ren|first2=Shulin|last3=Fu|first3=Yanning}} 11 : F-type main-sequence stars|Solar-type stars|Spectroscopic binaries|Draco (constellation)|Bayer objects|Durchmusterung objects|Flamsteed objects|Gliese and GJ objects|Henry Draper Catalogue objects|Hipparcos objects|HR objects |
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