ST Cephei

{{Starbox image

|image=250px

|caption= ST Cephei, as seen during the Digitized Sky Survey

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{{Starbox observe

|epoch=J2000

|constell=Cepheus

|ra={{RA|22|30|10.73791}}{{cite Gaia DR3|2007597289039287680}}

|dec={{DEC|+57|00|03.0712}}

|appmag_v=7.75 - 8.90

}}

{{Starbox character

|class=M2Ia-Iab{{cite journal |bibcode=1989ApJS...71..245K |title=The Perkins Catalog of Revised MK Types for the Cooler Stars |last1=Keenan |first1=Philip C. |last2=McNeil |first2=Raymond C. |journal=The Astrophysical Journal Supplement Series |date=1989 |volume=71 |page=245 |doi=10.1086/191373 }}

|b-v=2.28

|u-b=

|variable=LC

}}

{{Starbox astrometry

|radial_v=−66.6{{cite journal |bibcode=2019MNRAS.486..251D |title=Data-driven stellar parameters for southern TESS FGK targets |last1=Deacon |first1=N. R. |last2=Henning |first2=Th |last3=Kossakowski |first3=D. E. |journal=Monthly Notices of the Royal Astronomical Society |date=2019 |volume=486 |issue=1 |page=251 |doi=10.1093/mnras/stz722 |doi-access=free |arxiv=1903.03115 }}

|prop_mo_ra=−3.568

|prop_mo_dec=−3.096

|parallax=0.2162

|p_error=0.0239

|parallax_footnote=

|absmag_v=−3.73{{cite journal |bibcode=2009ApJ...703..420M |title=Red Supergiants in the Andromeda Galaxy (M31) |last1=Massey |first1=Philip |last2=Silva |first2=David R. |last3=Levesque |first3=Emily M. |last4=Plez |first4=Bertrand |last5=Olsen |first5=Knut A. G. |last6=Clayton |first6=Geoffrey C. |last7=Meynet |first7=Georges |last8=Maeder |first8=Andre |journal=The Astrophysical Journal |date=2009 |volume=703 |issue=1 |page=420 |doi=10.1088/0004-637X/703/1/420 |arxiv=0907.3767 }}

|absmag_bol=

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{{Starbox detail

|source=

|mass=9

|radius=175 - 290

|temperature=4200

|luminosity=12,246{{cite journal |bibcode=2020ApJ...902...24D |title=Short-term Variability of Evolved Massive Stars with TESS. II. A New Class of Cool, Pulsating Supergiants |last1=Dorn-Wallenstein |first1=Trevor Z. |last2=Levesque |first2=Emily M. |last3=Neugent |first3=Kathryn F. |last4=Davenport |first4=James R. A. |last5=Morris |first5=Brett M. |last6=Gootkin |first6=Keyan |journal=The Astrophysical Journal |date=2020 |volume=902 |issue=1 |page=24 |doi=10.3847/1538-4357/abb318 |doi-access=free |arxiv=2008.11723 }}

|gravity=0.92

|metal_fe=0.02

|rotational_velocity=

|age_gyr=

}}

{{Starbox catalog

|names={{odlist|BD=+56°2793|HD=239978|SAO=34529}}{{cite simbad |title=ST Cep |accesss-date=2025-03-23}}

}}

{{Starbox reference

|Simbad=ST+Cep

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ST Cephei (ST Cep), also known as BD+56°2793,[http://vizier.u-strasbg.fr/viz-bin/VizieR-S?V*%20ST%20Cep ST Cephei] (General Catalogue of Variable Stars) is a red supergiant and a variable star located in the constellation Cepheus. It has a variable apparent magnitude between 7.75 and 8.90, and is over a hundred times the radius of the Sun.

Distance

ST Cephei is very far from the Solar System, and its parallax was not measured by the Hipparcos satellite. Its membership in the Cepheus OB2-B stellar association allows its distance to be estimated at 830 parsecs, or 2,715 light years.{{cn|date=March 2025}}

Characteristics

File:STCepLightCurve.png light curve for ST Cephei, plotted from ASAS-SN data{{cite web |url=https://asas-sn.osu.edu/variables/lookup |website=ASAS-SN Variable Stars Database|title=ASAS-SN Variable Stars Database|publisher=ASAS-SN |access-date=16 December 2024}}]]

ST Cephei is a red supergiant of spectral type M3I—previously cataloged as M2I—with an effective temperature of 3,600 Kelvin. It is a large supergiant; estimates of its radius range from 175{{cite journal|doi=10.1051/0004-6361:20066353 |title=Atmospheric dynamics and the mass loss process in red supergiant stars |date=2007 |last1=Josselin |first1=E. |last2=Plez |first2=B. |journal=Astronomy & Astrophysics |volume=469 |issue=2 |pages=671–680 |arxiv=0705.0266 |bibcode=2007A&A...469..671J }} to 290 solar radii. Considering an intermediate radius between both values, if it were in the place of the Sun, its surface would extend to the Earth's orbit. Despite this, its size is far from the two known hypergiants in this constellation, μ Cephei and VV Cephei.{{cite journal |bibcode=2005ApJ...628..973L |title=The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not as Cool as We Thought |last1=Levesque |first1=Emily M. |last2=Massey |first2=Philip |last3=Olsen |first3=K. A. G. |last4=Plez |first4=Bertrand |last5=Josselin |first5=Eric |last6=Maeder |first6=Andre |last7=Meynet |first7=Georges |journal=The Astrophysical Journal |date=2005 |volume=628 |issue=2 |page=973 |doi=10.1086/430901 |arxiv=astro-ph/0504337 }}

The bolometric luminosity of ST Cephei is 8,400 times greater than that of the Sun. It has a mass 9 times greater than the Sun, at the limit from which stars end their lives by exploding as supernovae. Like other analogous supergiants, it loses mass; Its loss of stellar mass—in the form of dust, since the atomic and molecular gas could not be evaluated—is quantified at {{val|2.5|e=-9|ul=solar mass|up=year}}.

In 1910 it was announced that Evelyn Leland had discovered that the star is a variable star.{{cite journal |last1=Leland |first1=E. F. |last2=Pickering |first2=Edward C. |title=20 New Variable Stars in Harvard Map, Nos. 2, 5, 32, 44, and 53 |journal=Harvard College Observatory Circular |date=January 1910 |volume=152 |pages=1–3 |bibcode=1910HarCi.152....1L }} That same year it was given its variable star designation, ST Cephei.{{cite journal |last1=Dunér |first1=Nils Christofer |last2=Hartwig |first2=Ernst |last3=Müller |first3=G. |title=Benennung von neu entdeckten veränderlichen Sternen |journal=Astronomische Nachrichten |date=November 1910 |volume=186 |issue=17 |pages=273–286 |bibcode=1910AN....186..273D |doi=10.1002/asna.19101861702 }}

Listed as an LC irregular variable star, the brightness of ST Cephei varies by about two magnitudes, with no period recognized.

References

Category:Slow irregular variables

Cephei, ST

239978

Category:Cepheus (constellation)

Category:M-type supergiants

ST Cephei

Distance

Characteristics

See also

References