View source for Astronomy:M101 OT2015-1

; {{short description|Contact binary which resulted in one star}}{{Infobox supernova
| name = M101 OT2015-1
| image = Discovery Image of Luminous Red Nova in M101.jpg
| image_size = 300px
| caption = Discovery image
| epoch = [[Astronomy:J2000|J2000]]
| host = [[Astronomy:Pinwheel Galaxy|Pinwheel Galaxy]] (M101)
| constellation = [[Astronomy:Ursa Major|Ursa Major]]
| ra = {{RA|14|02|16.78}}<ref name=SIMBAD>{{cite simbad|title=NAME M101 OT2015-1|access-date=27 February 2018}}</ref>
| dec = {{DEC|+54|26|20.5}}<ref name=SIMBAD/>
| gal =
| discovery = February 10, 2015
| iauc =
| mag_v = 16.5
| distance = 21 Mly
| progenitor = 
| progenitor_type = 
| b-v = 
| notes =
}}

'''M101 OT2015-1''' (also known as '''PSN J14021678+5426205''', '''iPTF13afz''' and '''AT 2015dl''')<ref>{{Cite web|url=https://wis-tns.weizmann.ac.il/object/2015dl|title = AT 2015dl &#124; Transient Name Server}}</ref> is a [[Astronomy:Contact binary|contact binary]] that merged into a single star, in a process known as a [[Astronomy:Luminous red nova|luminous red nova]] (LRN). M101 OT2015-1 is an optical transient located in the [[Astronomy:Pinwheel Galaxy|Pinwheel Galaxy]] (M101). Luminous red novae are representatives of the sparsely populated class of exploding variables which is known since 1988 when such a star ([[Astronomy:M31-RV|M31-RV]]) appeared in the [[Astronomy:Messier 31|M31]] galaxy.<ref name=goranskij/><ref name=blagorodnova/>

==Discovery==
[[File:Discovered telescope.jpg|thumb|left|Astronomical Observatory of the Museum Vasile Pârvan in Bârlad, România]]
M101 OT2015-1 was discovered on February 10, 2015 by Dumitru Ciprian Vîntdevară from Planetarium and Astronomical Observatory of the Museum Vasile Pârvan in Bârlad, România. The transient is located in the outer reaches of a spiral arm of M101, at 489W and 324N of the measured position of the galaxy nucleus.<ref name=telegram/><ref name=telegram8599/><ref name=snname/>
The transient was discovered with a [[Astronomy:Newtonian telescope|Newtonian telescope]] 0,2 m + CCD camera ATIK 320E (on unfiltered) + EQ6 mount.
On February 13, 2015, the [[Earth:New Zealand|New Zealand]] astronomer Stu Parker, using a telescope located in {{wipe|Spain}}, confirmed that a new object was visible in the M101 galaxy.  The new object was initially reported as a possible supernova, with the designation PSN J14021678+5426205.  Later it was shown that the new star is not a supernova, and for a while its nature remained uncertain.<ref name=telegram/>  One month after the discovery, on March 11, 2015, an [[Astronomy:The Astronomer's Telegram|Astronomer's Telegram]] was published where the new star was described as a luminous red nova, confirmed spectroscopically.<ref name=telegram7206/>

The final confirmation came a year later, on 2016 January 28, from observations carried out in several astronomic observatories in Russia.<ref name=telegram8599/>
{{clear left}}

[[File:Spectrum of the LRN in M 101.jpg|thumb|upright=1.4|Spectrum of the LRN in [[Astronomy:M101 Group|M101]] obtained with the BTA telescope and the SCORPIO camera on February 24, 2015 near the maximum of the second outburst.<ref name=goranskij/>]]
[[File:M101OT2015-1LightCurve.png|thumb|upright=1.4|A red band light curve for M101 OT2015-1, adapted from Blagorodnova ''et al.'' (2017).<ref name=blagorodnova/> The inset plot shows the time near the outburst with an expanded scale.]]

== Observations ==
{| class="wikitable"|upright=1.4
|+ Pre-discovery observations of the LRN/M101<ref name=goranskij/>
|-
! Date !! JD 24... !! B !! V !! R !! Source

|-
| 1993.04.15|| 49093 || - || 22.0|| - || POSS II, Kodak IIIaJ
|-
| 2003.03.07-10 || 52707 || 21.6 || 21.2 || 20.90 || SDSS, ATel 7082
|-
| 2011.11.25 || 55891 || 20.95 || 20.95 || 21.03 || R. Pecce, Flickr.com
|-
| 2012.03.20 || 56007 || 21.74 || 21.47 || 21.13 || D. Hartmann, Astrobin
|-
| 2012.02.14-27 || 56009 || 21.34 || 21.06 || 20.63 || T. Hankock, RGB images
|-
| 2012.05.10 || 56058 || 21.12 || 21.35 || 21.30 || O. Bryzgalov, Flickr.com
|-
| 2012.05.26 || 56074 || 21.55 || 21.27 || 21.20 || O. Bryzgalov, Flickr.com
|-
| 2012.01-06 || 56109 || 21.30 || 20.97 || 20.69 || ATel 7069, LBT
|-
| 2013.02.01  || 56324 || - || - || 20.60 || ATel 7070, PTF
|-
| 2013.04 || 56360 || 20.48 || 20.50 || 20.36 || Z. Orbanic, Flickr.com
|-
| 2013.03-05 || 56398 || 20.6  || 20.4 || 20.40 || R. Pfile, Flickr.com
|-
| 2013.06.11 || 56455  || 20.95 || 20.73 || 20.30 || S. Furlong, Flickr.com
|-
| 2013.06.29 || 56473 || 21.0 || 20.5 || 20.9 || C. Frenzi, Flickr.com
|-
| 2014.06-07 || 56839 || 20.02 || 19.78 || 19.59 || ATel 7069, LBT
|-
| 2014.11.10 || 56971 || - || - || 16.36 || ATel 7070, PTF
|-
| 2014.11.13 || 56975 || - || 16.40 || - || K. Itagaki, CBAT
|-
| 2015.01.14 || 57036 || - || - || 17.50 || PTF
|-
| 2015.01.19 || 57042 || 20.20 || 18.80 || 18.23 || ATel 7069, LBT
|-
| 2015.01.20 || 57043  || - || 18.50 || - || K. Itagaki, CBAT
|-
| 2015.02.10|| 57064.4 || - || 17.50 || - || C. D. Vîntdevară, discovery
|}

== Other information ==
Although the nature of the object is still debated, its resemblance with other transients from the same LRN family points towards a possible binary origin. The unusual location of the progenitor star in the [[Astronomy:Hertzsprung gap|Hertzsprung gap]] supports the hypothesis that the most massive component had expanded beyond its [[Physics:Roche lobe|roche lobe]], initiating the [[Astronomy:Common envelope|common envelope]] phase. The outbursts detected for M101-OT2015-1 suggest that this CE was ejected on dynamical timescales, likely leaving a surviving close binary pair.  Further observations at [[Physics:Infrared|infrared]] wavelengths will help to show the exact nature of the M101 OT2015-1 system.<ref name=blagorodnova/>

== References ==
{{reflist|refs=

<ref name=blagorodnova>{{cite journal|bibcode=2017ApJ...834..107B|doi=10.3847/1538-4357/834/2/107|arxiv=1607.08248|title=Common Envelope Ejection for a Luminous Red Nova in M101|journal=The Astrophysical Journal|volume=834|issue=2|pages=107|year=2017|last1=Blagorodnova|first1=N|last2=Kotak|first2=R|last3=Polshaw|first3=J|last4=Kasliwal|first4=M. M|last5=Cao|first5=Y|last6=Cody|first6=A. M|last7=Doran|first7=G. B|last8=Elias-Rosa|first8=N|last9=Fraser|first9=M|last10=Fremling|first10=C|last11=Gonzalez-Fernandez|first11=C|last12=Harmanen|first12=J|last13=Jencson|first13=J|last14=Kankare|first14=E|last15=Kudritzki|first15=R.-P|last16=Kulkarni|first16=S. R|last17=Magnier|first17=E|last18=Manulis|first18=I|last19=Masci|first19=F. J|last20=Mattila|first20=S|last21=Nugent|first21=P|last22=Ochner|first22=P|last23=Pastorello|first23=A|last24=Reynolds|first24=T|last25=Smith|first25=K|last26=Sollerman|first26=J|last27=Taddia|first27=F|last28=Terreran|first28=G|last29=Tomasella|first29=L|last30=Turatto|first30=M|s2cid=43063445|display-authors=29 |doi-access=free }}</ref>

<ref name=telegram>{{cite web|publisher=Central Bureau for Astronomical Telegrams |url=http://www.cbat.eps.harvard.edu/unconf/followups/J14021678+5426205.html|title=CBAT "Transient Object Followup Reports"|access-date=2018-04-27}}</ref>

<ref name=telegram8599>{{cite journal|title=The remnant of the luminous red nova PSN J14021678+5426205/M 101 in infrared and optical ranges|author1=V. P. Goranskij |author2=A. M. Tatarnikov |author3=N. I. Shatsky |author4=A. E. Nadjip |author5=E. A. Barsukova |author6=A. F. Valeev|journal=The Astronomer's Telegram |year=2016 |volume=8599 |page=1 |url=http://www.astronomerstelegram.org/?read=8599|bibcode=2016ATel.8599....1G}}</ref>

<ref name=goranskij>{{cite web|author1=V. P. Goranskij |author2=E. A. Barsukova |author3=I. Spiridonova |author4=A. F. Valeev |author5=T. A. Fatkhullin |author6=A. S. Moskvitin |author7=O. V. Vozyakova |author8=D. V. Cheryasov |author9=B. S. Safonov |author10=A. V. Zharova |author11=T. Hancock |title=PSN J14021678+5426205 in the Galaxy M101 as a merger event in a massive binary system |page=18 |url=http://www.vgoranskij.net/lrn2015-in-m101.pdf|access-date=2018-04-27}}</ref>

<ref name=telegram7206>{{cite journal|title=Spectroscopy and photometry of the luminous red nova PSN J14021678+5426205 in M 101|author1=V. P. Goranskij |author2=D. V. Cherjasov |author3=B. S. Safonov |author4=O. V. Vosyakova |author5=E. A. Barsukova |author6=O. I. Spiridonova |author7=A. F. Valeev|journal=The Astronomer's Telegram |year=2015 |volume=7206 |page=1 |url=http://www.astronomerstelegram.org/?read=7206|bibcode=2015ATel.7206....1G}}</ref>

<ref name=snname>{{cite web|title=List of supernovae sorted by name for 2015|url=http://www.rochesterastronomy.org/sn2015/snname.html|access-date=2018-04-27}}</ref>

}}
[[Category:Luminous red novae]]

{{Sourceattribution|M101 OT2015-1}}