{{Short description|Star in the constellation Delphinus}} {{Starbox begin }} {{Starbox image |image = {{Location mark |image=Delphinus constellation map.svg|alt=|float=center|width=260|position=right |mark=Red circle.svg|mark_width=10|mark_link=1 Del |x=494|y=554 }} |caption=Location of 1 Delphini (circled) }} {{Starbox observe 2s | epoch = J2000 | component1 = A | constell = Delphinus | ra1 = {{RA|20|30|17.9623}}<ref name = DR3A/> | dec1 = {{DEC|+10|53|45.335}}<ref name = DR3A/> | appmag_v1 = 6.20{{±|0.01}}<ref name = Fabricius2002/> | component2 = B | ra2 = {{RA| 20|30|17.9505}}<ref name = DR3B/> | dec2 = {{DEC|+10|53|46.244}}<ref name = DR3B/> | appmag_v2 = 8.00{{±|0.01}}<ref name = Fabricius2002/> }} {{Starbox character | class = A1:III shell<ref name = Abt1995/> (A0e + A0)<ref name=kharchenko2007/> | b-v = −0.03<ref name=Ducati/> | u-b = −0.11<ref name=Ducati/> | variable = }} {{Starbox astrometry | radial_v = −15.5 ± 2<ref name=GCRV/> | absmag_v = −0.69<ref name = Anderson2012/> }} {{Starbox astrometry|no_heading=y | component1 = A | prop_mo_ra = +19.320 | prop_mo_dec = +4.645 | parallax = 4.6400 | p_error = 0.0616 | parallax_footnote = <ref name = DR3A/> | pm_footnote = <ref name = DR3A/> | component2 = B | parallax2 = 4.1851 | p_error2 = 0.1421 | parallax_footnote2 = <ref name = DR3B/> | prop_mo_ra2 = +19.545<ref name = DR3B/> | prop_mo_dec2 = +4.710<ref name = DR3B/> }} {{Starbox detail | component1 = A | mass = 3.1{{±|0.3}}<ref name = Anders2022/> | gravity = 3.66{{±|0.77}}<ref name = Anders2022/> | temperature = 10,651{{±|932|1156}}<ref name = Anders2022/> | rotational_velocity = 217<ref name=kubat2016/> | age_myr = 246<ref name = Gontcharov2012/> | metal_fe = 0.00<ref name = Gontcharov2012/> | component2 = B | gravity2 = 4.14{{±|0.19|0.47}}<ref name = Anders2022/> | rotational_velocity2 = 370<ref name=kubat2016/> }} {{Starbox catalogue | names = {{odlist|F = 1 Delphini|BD = +10°4303|HD = 195325|HIP = 101160|HR = 7836|SAO = 106172|WDS = J20303+1054AB}} }} {{Starbox reference | Simbad =1+Del }} {{Starbox end}} '''1 Delphini''' (1 Del) is the Flamsteed designation for a close binary star in the northern constellation of Delphinus. With a combined apparent magnitude of 6.08, it is barely visible to the naked eye, even under ideal conditions. Parallax measurements put the components at a distance 703 and 780 light years respectively. However, its approaching the Solar System with a radial velocity of {{val|15|ul=km/s}}.
1 Del consists of three components. The brightest of them has a magnitude of 6.1; a companion located around 0.9 arcseconds from the primary has an apparent magnitude of 8.1; and a third star, located much farther away at around 17 arcseconds from component A, is the faintest with a magnitude of around 14 and is an unrelated background object.<ref name=DR3C/>
The entire system has a stellar classification of A1: III sh, indicating that it is a white giant and a shell star. However, there is some uncertainty about the temperature class. When resolved, the secondary has a class of B9. 1 Del A has 3 times the mass of the Sun and an effective temperature of 10,651 K,<ref name = Anders2022/> giving it a bluish white glow. It is estimated to be almost 250 million years old and has a solar metallicity.<ref name = Gontcharov2012/> Both components spin rapidly, with projected rotational velocities of 217 and 370 km/s respectively.<ref name=kubat2016/> As for the peculiarities, the shell star is a primary component; the spectrum of the secondary shows broad absorption lines.<ref name=kubat2016/>
Due to the stability of the emission lines data from 1 Delphini has been used for developing models of shell stars and Be stars.<ref name=kubat2016/>
==References== {{reflist||refs=
<ref name = DR3A>{{Cite Gaia DR3|1753792931176132608}}</ref>
<ref name = DR3B>{{Cite Gaia DR3|1753792926878732672}}</ref>
<ref name = DR3C>{{Cite Gaia DR3|1753792926879479936}}</ref>
<ref name=kharchenko2007>{{cite journal |last1=Kharchenko |first1=N. V. |last2=Scholz |first2=R.-D. |last3=Piskunov |first3=A. E. |last4=Röser |first4=S. |last5=Schilbach |first5=E. |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 |journal=Astronomische Nachrichten |date=2007 |volume=328 |issue=9 |page=889 |doi=10.1002/asna.200710776 |arxiv=0705.0878 |bibcode=2007AN....328..889K }}</ref>
<ref name = Fabricius2002>{{cite journal |last1=Fabricius |first1=C. |last2=Høg |first2=E. |last3=Makarov |first3=V. V. |last4=Mason |first4=B. D. |last5=Wycoff |first5=G. L. |last6=Urban |first6=S. E. |title=The Tycho double star catalogue |journal=Astronomy & Astrophysics |date=March 2002 |volume=384 |issue=1 |pages=180–189 |doi=10.1051/0004-6361:20011822 |issn=0004-6361 |bibcode=2002A&A...384..180F |doi-access=free}}</ref>
<ref name=GCRV>{{cite journal |author=Ralph Elmer Wilson |date=1953 |title=General Catalogue of Stellar Radial Velocities |journal=Carnegie Institute Washington D.C. Publication |publisher=Carnegie Institution of Washington |bibcode=1953GCRV..C......0W |lccn=54001336}}</ref>
<ref name=kubat2016>{{cite journal |bibcode=2016A&A...587A..22K |title=Spectroscopy of close visual binary components of the stable shell star 1 Delphini |last1=Kubát |first1=Jiří |last2=Kubátová |first2=Brankica |last3=Doležalová |first3=Barbora |last4=Iliev |first4=Lubomir |last5=Šlechta |first5=Miroslav |journal=Astronomy and Astrophysics |year=2016 |volume=587 |pages=A22 |doi=10.1051/0004-6361/201526414 |arxiv=1601.05236 |s2cid=118706088 }}</ref>
<ref name = Anderson2012>{{cite journal |last1=Anderson |first1=E. |last2=Francis |first2=Ch. |title=XHIP: An extended hipparcos compilation |journal=Astronomy Letters |date=May 2012 |volume=38 |issue=5 |pages=331–346 |doi=10.1134/S1063773712050015 |language=en |issn=1063-7737 |bibcode=2012AstL...38..331A |arxiv=1108.4971|s2cid=255204555 }}</ref>
<ref name = Abt1995>{{cite journal |last1=Abt |first1=Helmut A. |last2=Morrell |first2=Nidia I. |title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars |journal=The Astrophysical Journal Supplement Series |date=July 1995 |volume=99 |pages=135 |doi=10.1086/192182 |issn=0067-0049 |bibcode=1995ApJS...99..135A |doi-access=free}}</ref>
<ref name=Ducati>{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|author1=Ducati, J. R.|year=2002}}</ref>
<ref name = Gontcharov2012>{{cite journal |last1=Gontcharov |first1=G. A. |title=Dependence of kinematics on the age of stars in the solar neighborhood |journal=Astronomy Letters |date=December 2012 |volume=38 |issue=12 |pages=771–782 |doi=10.1134/S1063773712120031 |issn=0320-0108 |bibcode=2012AstL...38..771G |arxiv=1606.08814|s2cid=255201789 }}</ref>
<ref name = Anders2022>{{cite journal |display-authors=1 |last1=Anders |first1=F. |last2=Khalatyan |first2=A. |last3=Queiroz |first3=A. B. A. |last4=Chiappini |first4=C. |last5=Ardèvol |first5=J. |last6=Casamiquela |first6=L. |last7=Figueras |first7=F. |last8=Jiménez-Arranz |first8=Ó. |last9=Jordi |first9=C. |last10=Monguió |first10=M. |last11=Romero-Gómez |first11=M. |last12=Altamirano |first12=D. |last13=Antoja |first13=T. |last14=Assaad |first14=R. |last15=Cantat-Gaudin |first15=T. |last16=Castro-Ginard |first16=A. |last17=Enke |first17=H. |last18=Girardi |first18=L. |last19=Guiglion |first19=G. |last20=Khan |first20=S. |last21=Luri |first21=X. |last22=Miglio |first22=A. |last23=Minchev |first23=I. |last24=Ramos |first24=P. |last25=Santiago |first25=B. X. |last26=Steinmetz |first26=M. |title=Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5 |journal=Astronomy & Astrophysics |date=February 2022 |volume=658 |pages=A91 |doi=10.1051/0004-6361/202142369 |issn=0004-6361 |bibcode=2022A&A...658A..91A |doi-access=free |arxiv=2111.01860 }}</ref>
}}
==Further reading== *{{cite journal | last1 = Merrill | first1 = Paul W. | last2 = Burwell | first2 = Cora G. | title = Second Supplement to the Mount Wilson Catalogue and Bibliography of Stars of Classes B and a whose Spectra have Bright Hydrogen Lines. | journal = The Astrophysical Journal | date = November 1949 | volume = 110 | page = 387 | issn = 0004-637X | eissn = 1538-4357 | doi = 10.1086/145215 | bibcode = 1949ApJ...110..387M | doi-access = free}}
*{{cite journal | last1 = Merrill | first1 = Paul W. | title = Spectra of Two Stars with Stable Shells | journal = The Astrophysical Journal | date = January 1952 | volume = 115 | page = 42 | issn = 0004-637X | eissn = 1538-4357 | doi = 10.1086/145507 | bibcode = 1952ApJ...115...42M | doi-access = free }}
*{{cite journal | last1 = van den Bos | first1 = W. H. | title = Micrometer measures of double stars. | journal = The Astronomical Journal | date = February 1958 | volume = 63 | page = 63 | issn = 0004-6256 | doi = 10.1086/107694 | bibcode = 1958AJ.....63...63V | doi-access = free }}
*{{cite journal | last1 = Ringuelet-Kaswalder | first1 = Adela E. | title = Shell Stars and Rotationally Unstable Be Stars | journal = Publications of the Astronomical Society of the Pacific | date = August 1963 | volume = 75 | issue = 445 | page = 323 | issn = 0004-6280 | eissn = 1538-3873 | doi = 10.1086/127960 | bibcode = 1963PASP...75..323R | doi-access = free}}
*{{cite journal | last1 = Gray | first1 = David F. | last2 = Marlborough | first2 = J. M. | title = Photoelectric Profile Measurements of Halpha and Hbeta in be Stars | journal = The Astrophysical Journal Supplement Series | date = March 1974 | volume = 27 | page = 121 | issn = 0067-0049 | eissn = 1538-4365 | doi = 10.1086/190291 | bibcode = 1974ApJS...27..121G | doi-access = free}}
{{Stars of Delphinus}} Delphini, 01 Category:Delphinus Category:Triple stars 101160 7836 195325 Category:Durchmusterung objects Category:Shell stars Category:A-type giants Category:Emission-line stars Category:Population I stars