IM Normae

{{Short description|Recurrent nova in the constellation Norma}}

{{Starbox begin

|name=IM Normae

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{{Starbox image

| image = 250px

| caption = A visual band light curve for IM Normae. The main plot shows the decline from the 2002 eruption, and the inset plot shows the periodic variation seen when the nova is in its quiescent state. Adapted from Schaefer (2010)

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{{Starbox observe

|epoch=J2000

|ra={{RA|15|39|26.465}}{{cite simbad|title=V* IM Nor|access-date=26 April 2015}}

|dec={{DEC|-52|19|17.99}}

|appmag_v=

|constell=Norma

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{{Starbox character

|class=white dwarf + ?

|b-v=

|u-b=

|variable=eclipsing recurrent nova (NR+E)

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{{Starbox astrometry

| parallax = 0.9946

| p_error = 0.4149

| parallax_footnote = {{cite DR2|5886055870915579648}}

| absmag_v = {{val|-4.4}}{{cite journal |doi=10.1093/mnras/sty2388 |title=The distances to Novae as seen by Gaia |journal=Monthly Notices of the Royal Astronomical Society |volume=481 |issue=3 |pages=3033–3051 |year=2018 |last1=Schaefer |first1=Bradley E. |doi-access=free |bibcode=2018MNRAS.481.3033S |arxiv=1809.00180 |s2cid=118925493 }}

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{{Starbox detail

| component1 = White dwarf

| mass = 1.21{{cite journal |doi=10.3847/1538-4357/aabfbd |title=The Masses and Accretion Rates of White Dwarfs in Classical and Recurrent Novae |journal=The Astrophysical Journal |volume=860 |issue=2 |pages=110 |year=2018 |last1=Shara |first1=Michael M. |last2=Prialnik |first2=Dina |last3=Hillman |first3=Yael |last4=Kovetz |first4=Attay |bibcode=2018ApJ...860..110S |arxiv=1804.06880 |s2cid=55851634 |doi-access=free }}

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{{Starbox catalog

|names=AAVSO 1532-52, Nova Normae 1920

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{{Starbox reference

| Simbad = IM+Nor

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{{Starbox end}}

IM Normae (IM Nor) is a recurrent nova in the constellation Norma, one of only ten known in the Milky Way. It has been observed to erupt in 1920 and 2002, reaching magnitude 8.5 from a baseline of 18.3. It was poorly monitored after the first eruption, so it is possible that it erupted in between these dates.{{cite journal|last=Schaefer|first=Bradley E.|date=2010|title=Comprehensive Photometric Histories of All Known Galactic Recurrent Novae|journal=The Astrophysical Journal Supplement|volume=187|issue=2|pages=275–373|doi=10.1088/0067-0049/187/2/275 |bibcode=2010ApJS..187..275S|arxiv = 0912.4426 |s2cid=119294221}}

The 1920 outburst was discovered by Ida Elizabeth Woods when she examined a Harvard Observatory photographic plate taken by the Bruce telescope in Arequipa, Peru, on July 7th of that year.{{cite journal |last1=Bailey |first1=S. I. |title=Variable Stars |journal=Harvard College Observatory Bulletin |bibcode=1920BHarO.734....1W |date=29 November 1920 |volume=734 |url=https://articles.adsabs.harvard.edu/pdf/1920BHarO.734....1W |access-date=8 October 2024}}

At minimum, IM Normae shows brightness variations of about 0.3 magnitudes. These consist of 0.2 magnitude dips that are interpreted as partial eclipses of the accretion disk, and continuous variations caused by one side of the secondary star being heated by the white dwarf and therefore brighter than the other face. The orbital period is 2.462 hours.{{cite journal |doi=10.1046/j.1365-8711.2003.06666.x |title=High-speed photometry of the recurrent nova IM Normae |journal=Monthly Notices of the Royal Astronomical Society |volume=343 |issue=1 |pages=313–314 |year=2003 |last1=Woudt |first1=P. A. |last2=Warner |first2=B. |doi-access=free |bibcode=2003MNRAS.343..313W |arxiv=astro-ph/0304002 |s2cid=17271577 }}