M33-013406.63

{{Short description|Star in the constellation of Triangulum}}

{{Starbox begin

| name = M33-013406.63

}}

{{Starbox image

| image = {{CSS image crop

|Image = File:M33-013406.63 Pan-STARRS.jpg

|bSize = 1806

|cWidth = 300

|cHeight = 300

|oTop = 232

|oLeft = 752}}

| caption = M33-013406.63 (brightest star at the center) by Pan-STARRS Data Release 1 in blue, g, and r filters.

| credit = NASA/UH-IfA

}}

{{Starbox observe

| epoch = J2000.0

| constell = Triangulum

| ra = {{RA|01|34|06.63}}{{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|last1=Van Leeuwen|first1=F.|year=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 |s2cid=18759600}}

| dec = {{DEC|+30|41|37.60}}

| appmag_v = 16.1

}}

{{Starbox character

| class = O

| type = Late O supergiant or candidate LBV

| variable = O9.5Ia / cLBV?

}}

{{Starbox astrometry

| dist_ly =

| dist_pc =

| absmag_v = –9.1 – –9.6

| absmag_bol = –12.2 – –12.7

}}

{{Starbox detail

| source={{cite journal |bibcode=2018MNRAS.480.3706K |title=On the evolutionary state of massive stars in transition phases in M33 |last1=Kourniotis |first1=M. |last2=Kraus |first2=M. |last3=Arias |first3=M. L. |last4=Cidale |first4=L. |last5=Torres |first5=A. F. |journal=Monthly Notices of the Royal Astronomical Society |year=2018 |volume=480 |issue=3 |page=3706 |doi=10.1093/mnras/sty2087 |doi-access=free |arxiv=1808.00008 }}

| component1 = A

| mass =

| luminosity = {{val|4.68|e=6}}

| radius = 80{{efn|name=radius1}}

| temperature = ~30,000

| gravity =

| metal_fe =

| rotational_velocity = {{val|75|5}}

| age_myr =

| component2 = B

| mass2 =

| luminosity2 = 407,380

| radius2 = 210{{efn|name=radius2}}

| temperature2 = 10,000

| gravity2 =

| metal_fe2 =

| rotational_velocity2 =

| age_myr2 =

}}

{{Starbox catalogue

| names=LGGS J013406.63+304147.8, B416

}}

{{Starbox reference

| Simbad = %5BHS80%5D+B416

}}

{{Starbox end}}

M33-013406.63, also known as B416 or UIT301,{{Cite journal|last1=Humphreys|first1=R. M.|last2=Sandage|first2=A.|date=November 1980|title=On the stellar content and structure of the spiral Galaxy M33|journal=The Astrophysical Journal Supplement Series|volume=44|pages=319|doi=10.1086/190696|bibcode=1980ApJS...44..319H|issn=0067-0049}} is a O-type blue evolved supergiant star in the constellation of Triangulum. It is located within the Triangulum Galaxy, which is approximately 2,380,000–3,070,000 light years away from Earth.

It is potentially one of the most luminous stars ever discovered, estimated to be approximately between 3 and 10 million times more luminous than the Sun, although it is thought likely to be a multiple star system.{{cite journal |doi=10.1088/0004-637X/790/1/48 |title=Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants |year=2014 |author-link1=Roberta M. Humphreys|last1=Humphreys |first1=Roberta M. |last2=Weis |first2=Kerstin |last3=Davidson |first3=Kris |last4=Bomans |first4=D. J. |last5=Burggraf |first5=Birgitta |journal=The Astrophysical Journal |volume=790 |issue=1 |pages=48 |arxiv=1407.2259 |bibcode=2014ApJ...790...48H |s2cid=119177378 }} Modelling of the spectrum based on some assumptions about the relative sizes of the two stars suggests a secondary around half a million times as luminous as the Sun and the primary over four million times as luminous as the Sun.

M33-013406.63 is embbed within a prominent ring shaped H II region, large regions of Ionized hydrogen clouds with lots of star formation occurring in them.{{Cite web |title=H II region {{!}} Astronomy, Star Formation & Nebulae {{!}} Britannica |url=https://www.britannica.com/science/H-II-region |access-date=2023-11-03 |website=www.britannica.com |language=en}}{{Cite journal |title=Nebular Spectroscopy: A Guide on H ii Regions and Planetary Nebulae |doi=10.1088/1538-3873/aa72c3 |date=2017 |last1=Peimbert |first1=Manuel |last2=Peimbert |first2=Antonio |last3=Delgado-Inglada |first3=Gloria |journal=Publications of the Astronomical Society of the Pacific |volume=129 |issue=978 |arxiv=1705.06323 |bibcode=2017PASP..129h2001P }} It is also near the center of the H II region it's in and possible associated with the nebula's origin.