28 Monocerotis

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

{{Starbox begin

| name = 28 Monocerotis

}}

{{Starbox image

| image = 250px

| caption = A visual band light curve for V645 Monocerotis, adapted from Stift (1979)

}}

{{Starbox observe

| epoch = J2000

| constell = Monoceros

| ra = {{RA|08|01|13.33574}}{{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%2039211 Vizier catalog entry]

| dec = {{DEC|-01|23|33.3935}}

| appmag_v = 4.69{{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=39211 Vizier catalog entry]

}}

{{Starbox character

| class = K4III

| b-v = +1.49{{cite journal | bibcode=2006yCat.2168....0M | title=VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991) | journal=VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie | volume=2168 | last1=Mermilliod | first1=J. C. | year=2006 }}[http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=II/168/ubvmeans&LID=%2B100065953 Vizier catalog entry]

| u-b = +1.76

}}

{{Starbox astrometry

| radial_v = +26.70{{Cite journal | doi=10.1134/S1063773706110065 | bibcode=2006AstL...32..759G| title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system| journal=Astronomy Letters| volume=32| issue=11| pages=759–771| year=2006| last1=Gontcharov| first1=G. A.|arxiv = 1606.08053 | s2cid=119231169}}

| prop_mo_ra = +67.60

| prop_mo_dec = −76.26

| parallax = 7.25

| p_error = 0.30

| parallax_footnote =

| absmag_v = −1.00

}}

{{Starbox detail

| mass = {{val|2.193|0.110}}

| radius = {{val|47.69|0.46|2.21}}

| temperature = {{val|3999|96|19|fmt=commas}}

| luminosity = {{val|524|42}}

| rotational_velocity = 2.2{{cite journal | bibcode=2014A&A...561A.126D | doi=10.1051/0004-6361/201220762 | arxiv=1312.3474 | title=A catalog of rotational and radial velocities for evolved stars | journal=Astronomy & Astrophysics | volume=561 | pages=A126 | year=2014 | last1=De Medeiros | first1=J. R. | last2=Alves | first2=S. | last3=Udry | first3=S. | last4=Andersen | first4=J. | last5=Nordström | first5=B. | last6=Mayor | first6=M. | s2cid=54046583 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/A%2bA/561/A126/table1&HD=65953 Vizier catalog entry]

| gravity = 1.68{{cite journal | bibcode=2016A&A...591A.118S | doi=10.1051/0004-6361/201628497 |arxiv=1605.07384 | title=The PASTEL catalogue: 2016 version | journal=Astronomy & Astrophysics | volume=591 | pages=A118 | year=2016 | last1=Soubiran | first1=Caroline | last2=Le Campion | first2=Jean-François | last3=Brouillet | first3=Nathalie | last4=Chemin | first4=Laurent | s2cid=119258214 }}

| metal_fe = −0.26

}}

{{Starbox catalog

| names = {{odlist | V=V645 Mon | BD=−00 1882 | FK5=2620 | GC=10870 | HIP=39211 | HR=3141 | HD=65953 | SAO=135380 }}

}}

{{Starbox reference

| Simbad = 28+Monocerotis

}}

{{Starbox end}}

28 Monocerotis is a single star in the equatorial constellation of Monoceros. It has an orange-hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.69. The distance to this star is approximately 450 light years based on parallax, and it has an absolute magnitude of −1.00. The star is drifting further away from the Sun with a radial velocity of +26.7 km/s.

This is an aging giant star with a stellar classification of K4III, having exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. The spectrum of the star shows abnormally strong lines of CN. It is classified as an FK Comae Berenices variable, varying by 0.02 magnitude over a period of 0.21 days. FK Comae Berenices variables are typically rapidly-rotating stars, but the measured projected rotational velocity of 28 Monocerotis is low. The star has expanded to 48 times the radius of the Sun. It is radiating 524 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,999 K.

Measurement of the star's proper motion anomaly by the Gaia spacecraft suggests a companion may be orbiting the star at a distance of {{val|1.9|ul=AU}}.