SN 1998S

{{Short description|Supernova in the constellation Ursa Major}}

{{Supernova

| name = SN 1998S

| image = SN1998S.jpg

| caption =R-band image of SN 1998S in NGC 3877 obtained on 1998 March 16.1 ut at t he Jacobus Kapteyn Telescope (JKT), La Palma (north is up and east is to the left).{{cite journal|last1=Fassia|first1=A.|last2=Meikle|first2=W. P. S.|last3=Vacca|first3=W. D.|last4=Kemp|first4=S. N.|last5=Walton|first5=N. A.|last6=Pollacco|first6=D. L.|last7=Smartt|first7=S.|last8=Oscoz|first8=A.|last9=Aragon-Salamanca|first9=A.|last10=Bennett|first10=S.|last11=Hawarden|first11=T. G.|last12=Alonso|first12=A.|last13=Alcalde|first13=D.|last14=Pedrosa|first14=A.|last15=Telting|first15=J.|last16=Arevalo|first16=M. J.|last17=Deeg|first17=H. J.|last18=Garzon|first18=F.|last19=Gomez-Roldan|first19=A.|last20=Gomez|first20=G.|last21=Gutierrez|first21=C.|last22=Lopez|first22=S.|last23=Rozas|first23=M.|last24=Serra-Ricart|first24=M.|last25=Zapatero-Osorio|first25=M. R.|title=Optical and infrared photometry of the Type IIn SN 1998S: days 11-146|journal=Monthly Notices of the Royal Astronomical Society|date=11 November 2000|volume=318|issue=4|pages=1093–1104|doi=10.1046/j.1365-8711.2000.03797.x|doi-access=free |arxiv = astro-ph/0006080 |bibcode = 2000MNRAS.318.1093F |s2cid=3073301}}

| epoch = J2000.0

| type = IIn

| host = NGC 3877

| constellation = Ursa Major

| ra =11^h 46^m 06.25^s

| dec =+47° 28' 55.5"

| gal = 150.7467 +65.9637

| discovery = {{circa}} 50.5 million years ago

(detected 2 March 1998 by Z. Wan)

| mag_v = 12 mag

| distance = {{circa}} 50.5 million ly

| progenitor_type = maybe Red supergiant

| b-v = ~ 0.2 mag

| notes = SN 1998S, AAVSO 1140+48

|event_type=Supernova}}

SN 1998S was a type IIn supernova that was detected in NGC 3877 in March 1998. At the time of discovery, SN 1998S was the brightest type IIn event observed,{{cite journal|last1=Fassia|first1=A.|last2=Meikle|first2=W. P. S.|last3=Chugai|first3=N.|last4=Geballe|first4=T. R.|last5=Lundqvist|first5=P.|last6=Walton|first6=N. A.|last7=Pollacco|first7=D.|last8=Veilleux|first8=S.|last9=Wright|first9=G. S.|last10=Pettini|first10=M.|last11=Kerr|first11=T.|last12=Puchnarewicz|first12=E.|last13=Puxley|first13=P.|last14=Irwin|first14=M.|last15=Packham|first15=C.|last16=Smartt|first16=S. J.|last17=Harmer|first17=D.|title=Optical and infrared spectroscopy of the type IIn SN 1998S: days 3-127|journal=Monthly Notices of the Royal Astronomical Society|date=11 August 2001|volume=325|issue=3|pages=907–930|doi=10.1046/j.1365-8711.2001.04282.x|doi-access=free |arxiv = astro-ph/0011340 |bibcode = 2001MNRAS.325..907F |s2cid=119514186}} although later outshone by SN 2010jl.{{Cite journal |last1=Ofek |first1=E. O. |last2=Zoglauer |first2=A. |last3=Boggs |first3=S. E. |last4=Barriere |first4=N. M. |last5=Reynolds |first5=S. P. |last6=Fryer |first6=C. L. |last7=Harrison |first7=F. A. |last8=Cenko |first8=S. B. |last9=Kulkarni |first9=S. R. |last10=Gal-Yam |first10=A. |last11=Arcavi |first11=I. |last12=Bellm |first12=E. |last13=Bloom |first13=J. S. |last14=Christensen |first14=F. |last15=Craig |first15=W. W. |date=2014-01-06 |title=SN 2010jl: Optical to hard X-ray observations reveal an explosion embedded in a ten solar mass cocoon |journal=The Astrophysical Journal |volume=781 |issue=1 |pages=42 |doi=10.1088/0004-637X/781/1/42 |issn=0004-637X|arxiv=1307.2247 |bibcode=2014ApJ...781...42O }}

It was discovered on 1998 March 2.68 UT in NGC 3877 by Z. Wan at a broadband (unfiltered) optical magnitude of +15.2.

Its spectrum showed prominent H and He emission lines with narrow peaks and broad wings, superimposed on a blue continuum. These narrow lines indicate the presence of a dense circumstellar medium (CSM) in the vicinity of the supernova. The high luminosity of SN1998S is due to the interaction of fast material (ejecta) with previously-expelled slowly-expanding material (CSM), which can more effectively convert kinetic energy of ejecta into radiation energy.{{cite journal |last1= Dessart |first1=Luc |title= Numerical simulations of super-luminous supernovae of type IIn |journal=MNRAS |year=2015 |bibcode= 2015MNRAS.449.4304D |arxiv= 1503.05463 |doi= 10.1093/mnras/stv609 |volume=449 |issue=4 |pages= 4304–4325|doi-access=free |s2cid=54221511 }}