{{Short description|Planetary nebula in the constellation Coma Berenices}} {{Infobox nebula | name = LoTr 5 | image = LoTr 5 Planetary Nebula.png | caption = LoTr 5 taken by Hunter Outten (Outten Astrophotography) | type = planetary | epoch = [[J2000]] | ra = {{RA|12|55|33.7462}}<ref name=GaiaDR2>{{cite DR2}}</ref> | dec = {{DEC|+25|53|30.561}}<ref name=GaiaDR2/> | dist_ly = {{nowrap|1,650 ± 39}} | dist_pc = {{nowrap|506 ± 12}}<ref name=Kovari2019>{{cite journal|bibcode=2019A&A...624A..83K|doi=10.1051/0004-6361/201834810|arxiv=1902.09460|title=Surface magnetic activity of the fast-rotating G5 giant IN Comae, central star of the faint planetary nebula LoTr 5|year=2019|last1=Kővári|first1=Zs.|last2=Strassmeier|first2=K. G.|last3=Oláh|first3=K.|last4=Kriskovics|first4=L.|last5=Vida|first5=K.|last6=Carroll|first6=T. A.|last7=Granzer|first7=T.|last8=Ilyin|first8=I.|last9=Jurcsik|first9=J.|last10=Kővári|first10=E.|last11=Weber|first11=M.|journal=Astronomy & Astrophysics|volume=624|pages=A83|s2cid=118977429}}</ref> | appdia = ~500″<ref name=Graham2004>{{cite journal|bibcode=2004MNRAS.347.1370G|doi=10.1111/j.1365-2966.2004.07342.x|title=The bipolarity of the highest Galactic latitude planetary nebula, LoTr 5 (PN G339.9+88.4), around IN Com|year=2004|last1=Graham|first1=M. F.|last2=Meaburn|first2=J.|last3=Lopez|first3=J. A.|last4=Harman|first4=D. J.|last5=Holloway|first5=A. J.|journal=Monthly Notices of the Royal Astronomical Society|volume=347|issue=4|pages=1370–1378|doi-access=free}}</ref> | constellation = [[Coma Berenices]] | radius_ly = 1.8 | radius_pc = 0.55<ref name=Jasniewicz1996>{{cite journal|bibcode=1996A&A...307..200J|title=The central star of LoTr 5 revisited|last1=Jasniewicz|first1=G.|last2=Thevenin|first2=F.|last3=Monier|first3=R.|last4=Skiff|first4=B. A.|journal=Astronomy and Astrophysics|volume=307|pages=200|year=1996}}</ref> | names = PN G339.9+88.4<ref name=SIMBAD>{{cite simbad|title=PN LoTr 5|access-date=2020-03-01}}</ref> }} '''LoTr 5''' is a large, faint [[planetary nebula]] in the [[constellation]] of [[Coma Berenices]]. In 2018, its [[stellar parallax|parallax]] was measured by ''[[Gaia (spacecraft)|Gaia]]'', giving a distance of about {{convert|1650|ly|pc|abbr=off|lk=on}}.<ref name=GaiaDR2/><ref name=Kovari2019/>
As of 2018, LoTr 5 has the highest [[galactic latitude]] of any known planetary nebula, being only 1.5 degrees away from the galactic north pole.<ref name=Aller2018>{{cite journal|bibcode=2018MNRAS.476.1140A|doi=10.1093/mnras/sty174|arxiv=1801.06032|title=A new look inside planetary nebula LoTr 5: A long-period binary with hints of a possible third component|year=2018|last1=Aller|first1=A.|last2=Lillo-Box|first2=J.|last3=Vučković|first3=M.|last4=Van Winckel|first4=H.|last5=Jones|first5=D.|last6=Montesinos|first6=B.|last7=Zorotovic|first7=M.|last8=Miranda|first8=L. F.|journal=Monthly Notices of the Royal Astronomical Society|volume=476|issue=1|pages=1140–1150|doi-access=free |s2cid=119477283}}</ref><!-- b = 88.5°, 90 - 88.5 = 1.5 --> Scientists noted this because if the distance of the nebula were found to be greater than a few hundred parsecs, then the gas from the nebula would be expanding into the [[galactic halo]], where there is little interaction with the [[interstellar medium]].<ref name=Graham2004/>
==Nomenclature== The nebula is most commonly referred to as LoTr 5, short for '''Longmore-Tritton 5'''. It was discovered in 1980 by A. J. Longmore and S. B. Tritton, who found the nebula on photographic plates taken at the [[UK Schmidt Telescope]].<ref name=LongmoreTritton>{{cite journal|bibcode=1980MNRAS.193..521L|doi=10.1093/mnras/193.3.521|title=A second list of new planetary nebulae found on United Kingdom 1.2-m Schmidt telescope plates|year=1980|last1=Longmore|first1=A. J.|last2=Tritton|first2=S. B.|journal=Monthly Notices of the Royal Astronomical Society|volume=193|issue=3|pages=521–524|doi-access=free}}</ref>
The central star has a number of different names. It is often referred to by its [[Henry Draper Catalogue]] designation '''HD 112313''', or by its [[variable star designation]] '''IN Comae Berenices'''. The [[General Catalogue of Variable Stars]] describes it as R:/PN, meaning it is likely a close [[binary star]] system with reflection of starlight being the cause of variation, as well as being part of the nucleus of a planetary nebula.<ref name=GCVS>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|display-authors=etal|author1=Samus, N. N.|author2=Durlevich, O. V.|year=2009}}</ref>
==Structure== LoTr 5 is one of the largest planetary nebulae known, with a radius of {{convert|1.8|ly|pc|abbr=off}}.<ref name=Jasniewicz1996/> It mostly emits light at a wavelength of 500.7 nm, corresponding to a [[doubly ionized oxygen]] line.<ref name=Graham2004/>
LoTr 5 is not spherical, but is instead a [[bipolar nebula]].<ref name=Graham2004/> Many bipolar and non-spherical nebulae are known to exist, but it is the processes that cause planetary nebulae to get their shapes are not clear, and have been the subject of much debate. However, the "binary hypothesis" posits that binary stars are more likely to produce non-spherical nebulae.<ref name="Douchin2015">{{cite journal|bibcode=2015MNRAS.448.3132D|doi=10.1093/mnras/stu2700|title=The binary fraction of planetary nebula central stars – II. A larger sample and improved technique for the infrared excess search|year=2015|last1=Douchin|first1=Dimitri|last2=De Marco|first2=Orsola|author2-link=Orsola De Marco|last3=Frew|first3=D. J.|last4=Jacoby|first4=G. H.|last5=Jasniewicz|first5=G.|last6=Fitzgerald|first6=M.|last7=Passy|first7=Jean-Claude|last8=Harmer|first8=D.|last9=Hillwig|first9=Todd|last10=Moe|first10=Maxwell|journal=Monthly Notices of the Royal Astronomical Society|volume=448|issue=4|pages=3132–3155|doi-access=free|hdl=10536/DRO/DU:30149879|hdl-access=free}}</ref> For LoTr 5, the binary system likely played a role in shaping the nebula.<ref name=Graham2004/>
A modelling of LoTr 5 shows that it is composed of two round lobes,<ref name=Graham2004/> making a peanut shape. The semimajor and semiminor axes are about 390 arcsec and 100 arcsec, respectively. The [[position angle]] of the long axis is 55°. The long axis is tilted 17° away from the line of sight, so there is considerable overlap between the farther northeastern lobe and the closer southwestern lobe.<ref name=Graham2004/> The nebula is not perfectly symmetrical: there appears to be a "hole" east of the nucleus, while the western side has an "arc" of emission.<ref name=Graham2004/>
==Binary system== {{Starbox begin |name=IN Comae Berenices}} {{Starbox image | image = [[Image:INComLightCurve.png|250px]] | caption = A [[Photometric_system#Photometric_letters|visual band]] [[light curve]] for IN Comae Berenices, adapted from Strassmeier ''et al.'' (1999)<ref name="Strassmeier"/> }} {{Starbox observe |epoch=[[J2000]] |constell=[[Coma Berenices]] |ra={{RA|12|55|33.7462}}<ref name=GaiaDR2/> |dec={{DEC|+25|53|30.561}}<ref name=GaiaDR2/> |appmag_v=8.69<ref name=Kovari2019/> }} {{Starbox character |class=G5 III<ref name=Kovari2019/> + sdO<ref name=Aller2018/> |u-b=+0.31<ref name=Alekseev/> |b-v=+0.81<ref name=Alekseev/> |v-r=+0.73<ref name=Alekseev/> |v-i=+1.20<ref name=Alekseev/> }} {{Starbox astrometry |radial_v=−16.50 ± 0.2<ref name=SIMBAD/> |prop_mo_ra=−25.588<ref name=GaiaDR2/> |prop_mo_dec=4.783<ref name=GaiaDR2/> |parallax=1.9768 |p_error=0.0462 |parallax_footnote=<ref name=GaiaDR2/> |absmag_bol=0.01 ± 0.08<ref name=Kovari2019/> }} {{Starbox orbit |reference=<ref name=Aller2018/> |period_unitless=2689 ± 52 |periastron=2455944 ± 25 |eccentricity=0.249 ± 0.018 |periarg=259.9 ± 4.8 |k1=4.630 ± 0.084 }} {{Starbox detail |source=<ref name=Aller2018/> |luminosity=78 ± 6 |gravity=2.6 ± 0.1 |temperature=5400 ± 100 |rotational_velocity=67.0 ± 1.5 |rotation=5.973 ± 0.008 d |radius={{val|11.1|+5.0|−2.2}} |mass=1.8 ± 0.4 |metal_fe=−0.10 ± 0.05 }} {{Starbox catalog |names={{odlist|BD=+26 2405|HIP=63087|HD=112313|SAO=82570}}<ref name=SIMBAD/> }} {{Starbox reference |Simbad=PN+LoTr+5 }} {{Starbox end}}
The central system at LoTr 5 has been known to be binary since 1983.<ref>{{cite journal|bibcode=1983ApJ...269..592F|doi=10.1086/161065|title=The binary central star of the planetary nebula LT-5|year=1983|last1=Feibelman|first1=W. A.|last2=Kaler|first2=J. B.|journal=The Astrophysical Journal|volume=269|pages=592|doi-access=free}}</ref> At the center there is an evolved [[G-type star]] (IN Comae Berenices) that is often classified as a [[giant star]] or a [[subgiant]], as well as a hot [[O-type subdwarf]] or [[white dwarf]] that is responsible for ionizing the nebula.<ref name=Aller2018/><ref name=Thevenin1997>{{cite journal|bibcode=1997A&A...320..913T|title=Barium-rich G stars in the nuclei of the planetary nebulae Abell 35 and LoTr5|last1=Thevenin|first1=F.|last2=Jasniewicz|first2=G.|journal=Astronomy and Astrophysics|volume=320|pages=913|year=1997}}</ref> The subdwarf is one of the hottest stars known,<ref name=Thevenin1997/> with an effective temperature of about {{val|150000|fmt=commas}} K.<ref name=Kovari2019/>
The two stars orbit each very slowly; in fact, with an [[orbital period]] of {{convert|2689|±|52|d|yr|lk=off}}, this is one of the longest periods for a binary system within a planetary nebula. The orbit is also moderately eccentric, at 0.249 ± 0.018.<ref name=Aller2018/> For a long time the hierarchical structure of the system has not been clear. Earlier studies came up with inner orbits around IN Comae Berenices with periods of 1.95 days<ref name=Jasniewicz1987>{{cite journal|bibcode=1987A&A...180..145J|title=The nucleus of LT-5 : An unusual triple system ?|last1=Jasniewicz|first1=G.|last2=Duquennoy|first2=A.|last3=Acker|first3=A.|journal=Astronomy and Astrophysics|volume=180|pages=145|year=1987}}</ref> or 1.75 days,<ref name=Malasan1997>{{cite journal|bibcode=1991AJ....101.2131M|doi=10.1086/115834|title=The central star of planetary nebula LT-5 - A triple system|year=1991|last1=Malasan|first1=Hakim Luthfi|last2=Yamasaki|first2=Atsuma|last3=Kondo|first3=Masayuki|journal=The Astronomical Journal|volume=101|pages=2131}}</ref> and/or suggesting a third star orbiting the central G-type star.<ref name=Jasniewicz1987/><ref name=Malasan1997/> The central stars' orbit appears to have a discrepancy with the nebula's "waist" such that the nebula's inclination of 17° may be too low. It is also possible, but more unlikely that the stellar orbits are not coplanar with the nebula's "waist", or that there is an undiscovered object in a close orbit with the degenerate star.<ref name=Jones2017>{{cite journal|bibcode=2017A&A...600L...9J|doi=10.1051/0004-6361/201730700|arxiv=1703.05096|title=The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5|year=2017|last1=Jones|first1=D.|last2=Van Winckel|first2=H.|last3=Aller|first3=A.|last4=Exter|first4=K.|last5=De Marco|first5=O.|journal=Astronomy & Astrophysics|volume=600|pages=L9|s2cid=55371290}}</ref>
IN Comae Berenices is known to be a [[variable star]], with its brightness varying on a cycle that is about 5.9 days long. This corresponds to the [[rotation period]] of the star, and the variability is attributed to [[starspot]]s, making it an [[RS Canum Venaticorum variable]]. With [[Doppler imaging]], the starspots were found to be lying at middle latitudes (40–50°), covering 22% of the star's surface, and about 600 K cooler than the rest of the star's surface.<ref name=Alekseev>{{cite journal|bibcode=2004Ap.....47..443A|doi=10.1023/B:ASYS.0000049781.42096.c6|title=Rotational Brightness Modulation and Starspots on the RS CVN-type Stars IN Com, IL Com, UX Ari, and V711 Tau|year=2004|last1=Alekseev|first1=I. Yu.|last2=Kozhevnikova|first2=A. V.|journal=Astrophysics|volume=47|issue=4|pages=443–453|s2cid=120473411}}</ref> Its spectrum shows it to be rich in [[barium]] and other [[s-process|''s''-process]] elements, making it a [[barium star]].<ref name=Aller2018/>
IN Comae Berenices emits [[X-ray]]s. These X-rays likely come from the star's [[stellar corona|corona]], and are associated with the star's rapid rotation.<ref>{{cite journal|bibcode=2010ApJ...721.1820M|doi=10.1088/0004-637X/721/2/1820|arxiv=1008.2910|title=X-Ray Emission from the Binary Central Stars of the Planetary Nebulae HFG 1, Ds 1, and LoTr 5|year=2010|last1=Montez|first1=Rodolfo|last2=De Marco|first2=Orsola|author2-link=Orsola De Marco|last3=Kastner|first3=Joel H.|last4=Chu|first4=You-Hua|journal=The Astrophysical Journal|volume=721|issue=2|pages=1820–1828|s2cid=119232433}}</ref>
In terms of structure, LoTr 5 is very similar to [[Abell 35]], another planetary nebula. Both are large and faint planetary nebulae with a binary nucleus, consisting of a rapidly rotating G-type star that is a rotational variable.<ref name=Thevenin1997/>
==References== <references> <ref name="Strassmeier">{{cite journal |last1=Strassmeier |first1=K. G. |last2=Serkowitsch |first2=E. |last3=Granzer |first3=Th. |title=Starspot photometry with robotic telescopes. U BV (RI)C and by light curves of 47 active stars in 1996/97 |journal=Astronomy & Astrophysics Supplement Series |date=November 1999 |volume=140 |pages=29–53 |doi=10.1051/aas:1999116 |bibcode=1999A&AS..140...29S |doi-access=free }}</ref> </references>
==External links== * {{cite web|url=https://astrodonimaging.com/gallery/lotr5/|date=2012-08-02|title=LoTr5|website=astrodonimaging.com|author=Goldman, Don|accessdate=2020-03-01}}
{{Coma Berenices}}
[[Category:Planetary nebulae]] [[Category:Binary stars]] [[Category:G-type giants]] [[Category:O-type subdwarfs]] [[Category:Coma Berenices]] [[Category:Spectroscopic binaries]] [[Category:RS Canum Venaticorum variables]] [[Category:Objects with variable star designations|Comae Berenices, IN]]