{{Short description|2018 nova that occurred in the constellation Carina}} {{Starbox begin}} {{Starbox image | image= {{Location mark |image=Carina constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=V906 Carinae |x=160|y=380 }} |caption=Location of V906 Carinae (circled) }} {{Starbox observe | epoch = J2000.0 | constell = Carina | ra = {{RA|10|36|15.428}}<ref name="Gaia EDR3"/> | dec = {{DEC|-59|35|53.67}}<ref name="Gaia EDR3"/> | appmag_v = 5.8 – 19.9<ref name="IVSI"/> }} {{Starbox character | class = | b-v = | u-b = | variable = Classical nova<ref name="luck"/> }} {{Starbox astrometry | radial_v = | prop_mo_ra = −7.511<ref name="Gaia EDR3"/> | prop_mo_dec = +3.267<ref name="Gaia EDR3"/> | parallax = 0.3140 | p_error = 0.3113 | parallax_footnote = <ref name="Gaia EDR3"/> | dist_pc = {{val|3300|2900|1500}}<ref name="aydi"/> }} {{Starbox detail | source = <ref name="wee"/> | component1 = White dwarf | mass = {{val|0.71|0.23|0.19}}<ref name="wee"/> | luminosity = 0.28 | temperature = 15,000 | radius = 0.03 | component2 = Donor | mass2 = 0.23 - 0.43 | luminosity2 = 0.03 | temperature2 = 4,951 | radius2 = ~0.24 }} {{Starbox catalog | names=ASASSN-18fv, Nova Carinae 2018, V906 Car, Gaia DR2 5254540166225866496 }} {{Starbox reference | Simbad = V906+Car }} {{Starbox end}}
[[File:V906CarLightCurve.png|thumb|left|The light curve of V906 Carinae, plotted from AAVSO data. The data from BRITE is shown on the inset plot.<ref name="aydi"/>]] '''V906 Carinae''', also known as '''Nova Carinae 2018''', was a nova in the Milky Way galaxy which appeared in the constellation Carina, near the 5th magnitude star HD 92063. It was discovered on images taken on 20.32 March 2018 by the All Sky Automated Survey for SuperNovae (ASAS-SN] telescope at the Cerro Tololo Inter-American Observatory. The ASAS-SN group assigned the name '''ASASSN-18fv''' to the object. The discovery image was saturated, allowing researchers to determine only that the object was brighter than apparent magnitude 10. An earlier image obtained by ASAS-SN on 26.32 March 2018 showed the nova was a magnitude ~10.4 object at that time, and the object was not detected on ASAS-SN images taken on 15.34 March 2018 and earlier.<ref name="atel11454"/>
V906 Carinae was featured in the Astronomy Picture of the Day on 25 March 2018.<ref name="apod"/>
Pre-discovery images of V906 Carinae were matched to a star of Gaia magnitude 20.1. On 21 March 2018, it had brightened to a Gaia magnitude 7.80 (visual magnitude 7.45),<ref name=strader/> and to magnitude 6.62 later the same day.<ref name=brown/> Also on 21 March 2018, long exposure spectrographic measurements of ASASSN-18fv, specifically in the 3800Å to 7300Å range, were captured using CCD imaging. Detailed analysis of the spectral data confirmed that ASASSN-18fv exhibited characteristics of a classical nova.<ref name=luckas/>
All novae are binary stars, with a "donor" star orbiting a white dwarf. The two stars are so close to each other that material is transferred from the donor to the white dwarf. In the case of V906 Carinae, data from the Transiting Exoplanet Survey Satellite suggests that the binary system has an orbital period of either 1.641 hours or twice that value. <ref name="aydi"/> The mass of the white dwarf has been estimated to be {{solar mass|0.71|link=y}}, and the donor is believed to be a dwarf of spectral type K or M and a mass of {{solar mass|0.23 - 0.43}}.<ref name="wee"/>
One of the stars monitored by the Bright-star Target Explorer (BRITE) nanosatellite constellation was HD 92063. V906 Carinae was close enough to that star to be serendipitously observed by BRITE.<ref name="wee"/> In the BRITE data, the nova's maximum brightness occurred on 14 April 2018. BRITE provided a measurement of the nova's brightness every 1.6 hours, allowing the fluctuations near the peak of the outburst to be seen clearly. There were eight post-maximum flares with amplitudes of a few tenths of a magnitude each of which lasted 1 to 3 days. These flares in the visible portion of the EM spectrum occurred at the same times that γ-ray flares were seen by Fermi-LAT. Because the γ-ray flares are believed to arise from shocks in the ejected material, their correlation with visible flares suggests that most of the visible light from the nova may be produced in shocks, rather than the nuclear burning on the white dwarf's surface.<ref name="aydi"/>
== References == <references> <ref name="Gaia EDR3">{{Cite Gaia EDR3|5254540166225866496}}</ref>
<ref name="IVSI">{{cite web |title=V0906 Car |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=611993 |website=The International Variable Star Index |publisher=AAVSO |access-date=13 January 2021}}</ref>
<ref name="luck">{{cite journal |last1=Luckas |first1=Paul |title=Spectroscopic Observations of ASASSN-18fv as a Classical Nova in the Iron Curtain Phase |journal=The Astronomer's Telegram |date=March 2018 |volume=11460 |page=1 |bibcode=2018ATel11460....1L }}</ref>
{<ref name="atel11454">{{cite journal |last1=Stanek |first1=K.Z. |last2=Holoien |first2=T.W.S. |last3=Kochanek |first3=C.S. |last4=Shields |first4=J.V. |last5=Thompson |first5=T.A. |last6=Chomiuk |first6=L.|author6-link=Laura Chomiuk |last7=Strader |first7=J. |last8=Shappee |first8=B.J. |last9=Prieto |first9=J.L. |last10=Dong |first10=Subo |last11=Stritzinger |first11=M. |title=ASAS-SN Discovery of a Possible, Very Bright Galactic Nova ASASSN-18fv |journal=The Astronomer's Telegram |date=March 2018 |volume=11454 |page=1 |bibcode=2018ATel11454....1S }}</ref>
<ref name=strader>{{Cite journal|bibcode=2018ATel11456....1S|last1=Strader|first1=Jay|title=Spectroscopy of the new bright Galactic transient ASASSN-18fv: A 12 mag outburst from a young stellar object?|url=http://www.astronomerstelegram.org/?read=11456|journal=The Astronomer's Telegram|date=March 21, 2018|volume=11456|page=1}}</ref>
<ref name=brown>{{Cite journal|bibcode=2018ATel11457....1B|last1=Brown|first1=Michael|title=Photometry and brightening of Galactic transient ASASSN-18fv|url=http://www.astronomerstelegram.org/?read=11457|journal=The Astronomer's Telegram|date=March 21, 2018|volume=11457|page=1}}</ref>
<ref name=luckas>{{Cite journal|bibcode=2018ATel11460....1L|last1=Luckas|first1=Paul|title=Spectroscopic Observations of ASASSN-18fv as a Classical Nova in the Iron Curtain Phase|url=http://www.astronomerstelegram.org/?read=11460|journal=The Astronomer's Telegram|date=March 21, 2018|volume=11460|page=1}}</ref>
<ref name="apod">{{cite web |title=Announcing Nova Carinae 2018 |url=https://apod.nasa.gov/apod/ap180325.html |website=Astronomy Picture of the Day |publisher=NASA |access-date=14 January 2021}}</ref>
<ref name="aydi">{{cite journal |last1=Aydi |first1=Elias |last2=Sokolovsky |first2=Kirill V. |last3=Chomiuk |first3=Laura|author3-link=Laura Chomiuk |last4=Steinberg |first4=Elad |last5=Li |first5=Kwan Lok |last6=Vurm |first6=Indrek |last7=Metzger |first7=Brian D. |last8=Strader |first8=Jay |last9=Mukai |first9=Koji |last10=Pejcha |first10=Ondrej |last11=Shen |first11=Ken J. |last12=Wade |first12=Gregg A. |last13=Kuschnig |first13=Rainer |last14=Moffat |first14=Anthony F.J. |last15=Pablo |first15=Herbert |last16=Pigulski |first16=Andrzej |last17=Popowicz |first17=Adam |last18=Weiss |first18=Werner |last19=Zwintz |first19=Konstanze |last20=Izzo |first20=Luca |last21=Pollard |first21=Karen R. |last22=Handler |first22=Gerald |last23=Ryder |first23=Stuart D. |last24=Filipovic |first24=Miroslav D. |last25=Alsaberi |first25=Rami Z.E. |last26=Manojlovic |first26=Perica |last27=Lopes de Oliveira |first27=Raimundo |last28=Walter |first28=Frederick M. |last29=Vallely |first29=Patrick J. |last30=Buckley |first30=David A.H. |last31=Brown |first31=Michael J.I. |last32=Harvey |first32=Eamonn J. |last33=Kawash |first33=Adam |last34=Kniazev |first34=Alexei |last35=Kochanek |first35=Christopher S. |last36=Linford |first36=Justin |last37=Mikolajewska |first37=Joanna |last38=Molaro |first38=Paolo |last39=Orio |first39=Marina |last40=Page |first40=Kim L. |last41=Shappee |first41=Benjamin J. |last42=Sokoloski |first42=Jennifer L. |title=Direct evidence for shock-powered optical emission in a nova |journal=Nature Astronomy |date=April 2020 |volume=4 |issue=8 |pages=776–780 |doi=10.1038/s41550-020-1070-y |arxiv=2004.05562 |bibcode=2020NatAs...4..776A |s2cid=215744948 }}</ref>
<ref name="wee">{{cite journal |last1=Wee |title=Multiwavelength Photometry and Progenitor Analysis of the Nova V906 Car |journal=The Astrophysical Journal |date=August 2020 |volume=899 |issue=2 |page=162 |doi=10.3847/1538-4357/aba3cc |arxiv=2006.14336 |bibcode=2020ApJ...899..162W |s2cid=220055758 |doi-access=free }}</ref> </references>
==External links==
* {{APOD|title=Announcing Nova Carinae 2018|date=25 March 2018}}
{{Stars of Carina}} {{2018 in space}}
Category:Novae Category:Carina (constellation) 20180320 Carinae, V906 Category:Objects with ASASSN designations