Delta Hydri

{{Short description|Star in the constellation Hydrus}}

{{Starbox begin

| name = δ Hydri

}}

{{Starbox image

|image=

{{Location mark

|image=Hydrus constellation map.svg|alt=|float=center|width=280

|label=|position=right

|mark=Red circle.svg|mark_width=10|mark_link=Delta Hydri

|x=524|y=520

}}

|caption=Location of δ Hydri (circled)

}}

{{Starbox observe

| epoch = J2000

| constell = Hydrus

| ra = {{RA|02|21|44.94286}}{{cite journal | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | last1=Van Leeuwen | first1=F. | s2cid=18759600 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2011001 Vizier catalog entry]

| dec = {{DEC|-68|39|33.9038}}

| appmag_v = 4.09{{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 |last1=Ducati |first1=J. R. |year=2002 }}

}}

{{Starbox character

| class = A2 V{{cite journal | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | title=XHIP: An extended hipparcos compilation | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | s2cid=119257644 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=V/137D/XHIP&HIP=11001 Vizier catalog entry]

| b-v = +0.03

| u-b = +0.05

}}

{{Starbox astrometry

| radial_v = +6.00{{cite journal | bibcode=2007AN....328..889K | doi=10.1002/asna.200710776| 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| volume=328| issue=9| pages=889| year=2007| last1=Kharchenko| first1=N.V.| last2=Scholz| first2=R.-D.| last3=Piskunov| first3=A.E.| last4=Röser| first4=S.| last5=Schilbach| first5=E.|arxiv = 0705.0878 | s2cid=119323941}}

| prop_mo_ra = -49.95

| prop_mo_dec = +2.48

| parallax = 23.35

| p_error = 0.34

| parallax_footnote =

| absmag_v = 0.92

}}

{{Starbox detail

| mass = 2.25{{cite journal | bibcode=1999A&A...352..555A | arxiv=astro-ph/9911002 | title=Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures | journal=Astronomy and Astrophysics | volume=352 | pages=555–562 | last1=Allende Prieto | first1=C. | last2=Lambert | first2=D. L. | year=1999 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/A%2bA/352/555/table1&Name=HIP11001 Vizier catalog entry]

| radius = 2.3

| temperature = {{Val|9880|336|fmt=commas}}{{cite journal | bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146 | arxiv=1501.03154 | title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets | journal=The Astrophysical Journal | volume=804 | issue=2 | pages=146 | year=2015 | last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A. | s2cid=33401607 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/ApJ/804/146/table5&HIP=11001 Vizier catalog entry]

| luminosity = 39.52

| rotational_velocity = 162

| gravity = 3.98

| metal_fe = +0.12

| age_myr = 209

}}

{{Starbox catalog

| names = {{odlist | B=δ Hyi | CPD=−69°113 | FK5=1065 | HD=15008 | HIP=11001 | HR=705 | SAO=248545 | GC=2872 }}

}}

{{Starbox reference

| Simbad = Delta+Hydri

}}

{{Starbox end}}

Delta Hydri, Latinized from δ Hydri, is a single,{{citation | display-authors=1 | last1=Rodriguez | first1=David R. | last2=Duchêne | first2=Gaspard | last3=Tom | first3=Henry | last4=Kennedy | first4=Grant M. | last5=Matthews | first5=Brenda | last6=Greaves | first6=Jane | last7=Butner | first7=Harold | title=Stellar multiplicity and debris discs: an unbiased sample | journal=Monthly Notices of the Royal Astronomical Society | volume=449 | issue=3 | pages=3160–3170 | date=May 2015 | doi=10.1093/mnras/stv483 | doi-access=free | arxiv=1503.01320 | bibcode=2015MNRAS.449.3160R | s2cid=119237891 | postscript=. }} white-hued star in the southern constellation of Hydrus. It is bright enough to be faintly visible to the naked eye with an apparent visual magnitude of 4.09. The distance to this star, based upon an annual parallax shift of 23.35 mas, is about 140 light years. It is moving away from the Sun with a radial velocity of +6 km/s.

This is an ordinary A-type main-sequence star with a stellar classification of A2 V It is about 209 million years old and has a high rate of spin, showing a projected rotational velocity of 162 km/s. This is giving the star an oblate shape with an equatorial bulge that is 7% larger than the polar radius.{{citation | last1=van Belle, Gerard T. | title=Interferometric observations of rapidly rotating stars | journal=The Astronomy and Astrophysics Review | volume=20 | issue=1 | page=51 | date=March 2012 | doi=10.1007/s00159-012-0051-2 | bibcode=2012A&ARv..20...51V | postscript=. | arxiv=1204.2572 | s2cid=119273474 }} The star has 2.25 times the mass of the Sun and 2.3 times the Sun's radius. It is radiating 39.5 times the Sun's luminosity from its photosphere at an effective temperature of around 9.880. Delta Hydri has been checked for an infrared excess, but none was found.