Editing Serpens (section)

===Stars===
{{See also|List of stars in Serpens}}

====Head stars====
[[File:SerpensCaputCC.jpg|thumb|left|200px|The constellation Serpens (Caput) as it can be seen by the naked eye|alt=The pattern of stars in Serpens Caput seen with the naked eye, with a triangle marking the head and a line of stars extending down marking the upper body]]
Marking the heart of the serpent is the constellation's brightest star, [[Alpha Serpentis]]. Traditionally called Unukalhai,<ref>{{cite book
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref> is a [[red giant]] of [[spectral type]] K2III located approximately 23 parsecs distant with a visual [[apparent magnitude|magnitude]] of 2.630 ± 0.009,<ref name="AlphaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=alf+Ser |title = * Alpha Serpentis – Star in double system|publisher = [[SIMBAD]] | access-date = 18 April 2014}}</ref> meaning it can easily be seen with the naked eye even in areas with substantial light pollution. A faint companion is in orbit around the red giant star,<ref name="Eggleton">{{Cite journal | doi = 10.1111/j.1365-2966.2008.13596.x| title = A catalogue of multiplicity among bright stellar systems| year = 2008| last1 = Eggleton | first1 = P. P.| last2 = Tokovinin | first2 = A. A.| journal = Monthly Notices of the Royal Astronomical Society| volume = 389| issue = 2| pages = 869| doi-access = free| bibcode = 2008MNRAS.389..869E|arxiv = 0806.2878 | s2cid = 14878976}}</ref> although it is not visible to the naked eye. Situated near Alpha is [[Lambda Serpentis]], a magnitude 4.42 ± 0.05 star rather similar to the Sun<ref name="daSilva">{{Cite journal | doi = 10.1051/0004-6361/201118751| title = Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: A chemo-chronological analysis| journal = Astronomy & Astrophysics| volume = 542| pages = A84| year = 2012| last1 = Da Silva | first1 = R.| last2 = Porto De Mello | first2 = G. F.| last3 = Milone | first3 = A. C.| last4 = Da Silva | first4 = L.| last5 = Ribeiro | first5 = L. S.| last6 = Rocha-Pinto | first6 = H. J. | bibcode = 2012A&A...542A..84D|arxiv = 1204.4433 | s2cid = 118450072}}</ref> positioned only 12 parsecs away.<ref name="LambdaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=lam+Ser |title = * Lambda Serpentis – Star|publisher = SIMBAD | access-date = 20 May 2014}}</ref> It has an exoplanet orbiting around it.<ref>{{citation|arxiv=2105.11583|year=2021|title=The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades|last1=Rosenthal|first1=Lee J.|last2=Fulton|first2=Benjamin J.|last3=Hirsch|first3=Lea A.|last4=Isaacson|first4=Howard T.|last5=Howard|first5=Andrew W.|last6=Dedrick|first6=Cayla M.|last7=Sherstyuk|first7=Ilya A.|last8=Blunt|first8=Sarah C.|last9=Petigura|first9=Erik A.|last10=Knutson|first10=Heather A.|last11=Behmard|first11=Aida|last12=Chontos|first12=Ashley|last13=Crepp|first13=Justin R.|last14=Crossfield|first14=Ian J. M.|last15=Dalba|first15=Paul A.|last16=Fischer|first16=Debra A.|last17=Henry|first17=Gregory W.|last18=Kane|first18=Stephen R.|last19=Kosiarek|first19=Molly|last20=Marcy|first20=Geoffrey W.|last21=Rubenzahl|first21=Ryan A.|last22=Weiss|first22=Lauren M.|last23=Wright|first23=Jason T.|journal=The Astrophysical Journal Supplement Series|volume=255|issue=1 |page=8|doi=10.3847/1538-4365/abe23c|bibcode=2021ApJS..255....8R |s2cid=235186973 |doi-access=free }}</ref> Another [[solar analog]] in Serpens is the primary of [[Psi Serpentis]], a binary star<ref name="Hall">{{Cite journal | doi = 10.1088/0004-6256/138/1/312| title = The Activity and Variability of the Sun and Sun-Like Stars. Ii. Contemporaneous Photometry and Spectroscopy of Bright Solar Analogs| journal = The Astronomical Journal| volume = 138| issue = 1| pages = 312| year = 2009| last1 = Hall | first1 = J. C. | last2 = Henry | first2 = G. W. | last3 = Lockwood | first3 = G. W. | last4 = Skiff | first4 = B. A. | last5 = Saar | first5 = S. H. | bibcode = 2009AJ....138..312H| citeseerx = 10.1.1.216.9004| s2cid = 12332945}}</ref> located slightly further away at approximately 14 parsecs.<ref name="PsiSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=psi+Ser |title = * Psi Serpentis – Double or multiple star|publisher = SIMBAD | access-date = 21 June 2014}}</ref>

[[Beta Serpentis|Beta]], [[Gamma Serpentis|Gamma]], and [[Iota Serpentis]] form a distinctive triangular shape marking the head of the snake, with [[Kappa Serpentis]] (the proper name is Gudja<ref name="IAU-CSN">{{Cite web
  |url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt
  |title=IAU Catalog of Star Names
  |publisher=International Astronomical Union
  |access-date=2018-09-17}}</ref>) being roughly midway between Gamma and Iota. The brightest of the four with an apparent magnitude of roughly 3.67, Beta Serpentis is a white main-sequence star roughly 160 parsecs distant.<ref name="BetaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=bet+Ser |title = * Beta Serpentis – Star in double system|publisher = SIMBAD | access-date = 12 May 2014}}</ref> It is likely that a nearby 10th-magnitude star<ref name="BetaBSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=bet+Ser+B |title = * Beta Serpentis B – Star in double system|publisher = SIMBAD | access-date = 12 May 2014}}</ref> is physically associated with Beta, although it is not certain.<ref name="Shaya">{{Cite journal | doi = 10.1088/0067-0049/192/1/2| title = Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of The Hipparcos Catalogue| journal = The Astrophysical Journal Supplement Series| volume = 192| issue = 1| pages = 2| year = 2011| last1 = Shaya | first1 = E. J. | last2 = Olling | first2 = R. P. | bibcode = 2011ApJS..192....2S|arxiv = 1007.0425 | s2cid = 119226823}}</ref> The [[Mira variable]] [[R Serpentis]], situated between Beta and Gamma, is visible to the naked eye at its maximum of 5th-magnitude, but, typical of Mira variables, it can fade to below magnitude 14.<ref name="RAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34592 |title=R Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=22 May 2014}}</ref> Gamma Serpentis itself is an F-type [[subgiant]] located only 11 parsecs distant and thus is quite bright, being of magnitude 3.84 ± 0.05.<ref name="GammaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=gam+Ser |title = * Gamma Serpentis – Variable star|publisher = SIMBAD | access-date = 22 May 2014}}</ref> The star is known to show [[solar-like oscillations]].<ref name="Bi">{{Cite journal | doi = 10.1086/521575| title = Seismological Analysis of the Stars γ Serpentis and ι Leonis: Stellar Parameters and Evolution| journal = The Astrophysical Journal| volume = 673| issue = 2| pages = 1093–1105| year = 2008| last1 = Bi | first1 = S. -L. | last2 = Basu | first2 = S. | last3 = Li | first3 = L. -H. | bibcode = 2008ApJ...673.1093B| doi-access = free}}</ref> Iota Serpentis is a binary star system.<ref name="Muterspaugh 2010">{{cite journal
 | title=The Phases Differential Astrometry Data Archive. II. Updated Binary Star Orbits and a Long Period Eclipsing Binary
 | last1=Muterspaugh | first1=Matthew W. | last2=Hartkopf | first2=William I.
 | last3=Lane | first3=Benjamin F. | last4=O’Connell | first4=J.
 | last5=Williamson | first5=M. | last6=Kulkarni | first6=S. R.
 | last7=Konacki | first7=Maciej | last8=Burke | first8=Bernard F.
 | last9=Colavita | first9=M. M. | last10=Shao | first10=M.
 | last11=Wiktorowicz | first11=Sloane J. | display-authors=1
 | journal=The Astronomical Journal
 | volume=140 | issue=6 | pages=1623–1630 | year=2010
 | arxiv=1010.4043 | bibcode=2010AJ....140.1623M
 | doi=10.1088/0004-6256/140/6/1623 | s2cid=6030289 }}</ref>

[[Delta Serpentis]], forming part of the body of the snake between the heart and the head, is a multiple star system<ref name="Malkov">{{Cite journal | doi = 10.1051/0004-6361/201219774| title = Dynamical masses of a selected sample of orbital binaries| journal = Astronomy & Astrophysics| volume = 546| pages = A69| year = 2012| last1 = Malkov | first1 = O. Y. | last2 = Tamazian | first2 = V. S.| last3 = Docobo | first3 = J. A.| last4 = Chulkov | first4 = D. A.| bibcode = 2012A&A...546A..69M| doi-access = free}}</ref> positioned around 70 parsecs from Earth. Consisting of four stars, the system has a total apparent magnitude of 3.79 as viewed from Earth,<ref name="DeltaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=del+Ser |title = * Delta Serpentis – Double or multiple star|publisher = SIMBAD | access-date = 18 May 2014}}</ref> although two of the stars, with a combined apparent magnitude of 3.80, provide nearly all the light.<ref name="DeltaBSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=del+Ser+B |title = * Delta Serpentis B – Star in double system|publisher = SIMBAD | access-date = 18 May 2014}}</ref> The primary, a white subgiant, is a [[Delta Scuti variable]] with an average apparent magnitude of 4.23.<ref name="DeltaAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34969 |title=Delta Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=18 May 2014}}</ref> Positioned very near Delta, both in the night sky and likely in actual space at an estimated distance of around 70 parsecs,<ref name="16Simbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=16+Ser |title = * 16 Serpentis – Star|publisher = SIMBAD | access-date = 24 May 2014}}</ref> is the [[barium star]] [[16 Serpentis]].<ref name="Tomkin">{{Cite journal | doi = 10.1086/164821| title = Heavy-element abundances in the mild barium stars Omicron Virginis and 16 Serpentis| journal = The Astrophysical Journal| volume = 311| pages = 819| year = 1986| last1 = Tomkin | first1 = J. | last2 = Lambert | first2 = D. L. | bibcode = 1986ApJ...311..819T| doi-access = free}}</ref> Another notable variable star visible to the naked eye is [[Chi Serpentis]], an [[Alpha² Canum Venaticorum variable]] situated midway between Delta and Beta which varies from its median brightness of 5.33 by 0.03 magnitudes over a period of approximately 1.5 days.<ref name="ChiAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34972 |title=Chi Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=26 May 2014}}</ref> Chi Serpentis is a [[Ap and Bp stars|chemically peculiar]] star.<ref name=Loden1983>{{citation
 | title=A physical study of the Ursa Major cluster (with special attention to the peculiar A stars)
 | last1=Loden | first1=L. O.
 | journal=Astronomy and Astrophysics Supplement Series
 | volume=53 | date=July 1983 | pages=33–42
 | bibcode=1983A&AS...53...33L | postscript=. }}</ref>

The two stars in Serpens Caput that form part of the Snake's body below the heart are [[Epsilon Serpentis|Epsilon]] and Mu Serpentis, both third-magnitude [[A-type main-sequence star]]s.<ref name="EpsilonSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eps+Ser |title = * Epsilon Serpentis – Star|publisher = SIMBAD | access-date = 26 May 2014}}</ref><ref name="MuSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=32+Ser |title = * Mu Serpentis – Star|publisher = SIMBAD | access-date = 26 May 2014}}</ref> Both have a peculiarity: Epsilon is an [[Am star]],<ref name="Adelman">{{Cite journal | doi = 10.1046/j.1365-8711.1998.01859.x| title = Elemental abundance analyses with DAO spectrograms -- XX. The early a stars epsilon Serpentis, 29 Vulpeculae and sigma Aquarii| journal = Monthly Notices of the Royal Astronomical Society| volume = 300| issue = 2| pages = 359| year = 1998| last1 = Adelman | first1 = S. J.| last2 = Albayrak | first2 = B.| bibcode = 1998MNRAS.300..359A| doi-access = free}}</ref> while Mu is a binary.<ref name="Gontcharov">{{Cite journal | doi = 10.1016/j.newast.2009.09.006| title = Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos II. Preliminary orbits for six astrometric binaries| journal = New Astronomy| volume = 15| issue = 3| pages = 324–331| year = 2010| last1 = Gontcharov | first1 = G. A. | last2 = Kiyaeva | first2 = O. V. | bibcode = 2010NewA...15..324G|arxiv = 1606.08182 | s2cid = 119252073}}</ref> Located slightly northwest of Mu is [[36 Serpentis]], another A-type main-sequence star. This star also has a peculiarity; it is a binary with the primary component being a [[Lambda Boötis star]], meaning that it has solar-like amounts of [[carbon]], [[nitrogen]], and [[oxygen]], while containing very low amounts of [[iron peak]] elements.<ref name="Nikolov">{{cite journal |last1=Nikolov |first1=G. |last2=Atanasova |first2=E. |last3=Iliev |first3=I. K. |last4=Paunzen |first4=E. |last5=Barzova |first5=I. S. |title=Spectroscopic orbit determination of two metal-weak dwarf stars: HD64491 and HD141851 |journal=Contributions of the Astronomical Observatory Skalnaté Pleso |volume=38 |issue=2 |pages=433–434 |date=April 2008 |bibcode=2008CoSka..38..433N}}</ref> The secondary star has also been a source of X-ray emissions.<ref name=Mason2010>{{cite journal
 | title=Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs
 | display-authors=1 | last1=Mason | first1=Brian D.
 | last2=Hartkopf | first2=William I. | last3=Tokovinin | first3=Andrei
 | journal=The Astronomical Journal
 | volume=140 | issue=3 | pages=735–743 | date=September 2010
 | doi=10.1088/0004-6256/140/3/735 | bibcode=2010AJ....140..735M | doi-access=free }}</ref> [[25 Serpentis]], positioned a few degrees northeast of Mu Serpentis, is a [[spectroscopic binary]]<ref name="Petrie">{{cite journal|last1=Petrie |first1=R. M. |last2=Phibbs |first2=Edgar |title=Redetermination of the Spectrographic Orbits of Iota Pegasi and 25 Serpentis |journal=Publications of the Dominion Astrophysical Observatory Victoria |volume=8 |pages=225–234 |year=1950 |bibcode=1950PDAO....8..225P}}</ref> consisting of a hot [[blue giant|B-type giant]] and an A-type main-sequence star. The primary is a [[slowly pulsating B star]], which causes the system to vary by 0.03 magnitudes.<ref name="25AAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34909 |title=PT Serpentis |author1=VSX |last2=Otero |first2=S. A|date=10 February 2012 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=28 May 2014}}</ref>

Serpens Caput contains many [[RR Lyrae variable]]s, although most are too faint to be seen without professional photography. The brightest is [[VY Serpentis]], only of 10th magnitude. This star's period has been increasing by approximately 1.2 seconds per century.<ref name="Wunder">{{cite journal |last1=Wunder |first1=E. |title=Period Changes of Bright RR Lyrae Stars SU Dra and VY Ser |journal=Information Bulletin on Variable Stars |volume=3669 |issue=1 |page=IBVS Homepage |date=October 1991 |bibcode=1991IBVS.3669....1W }}</ref> A variable star of a different kind is [[Tau4 Serpentis|Tau<sup>4</sup> Serpentis]], a cool red giant that pulsates between magnitudes 5.89 and 7.07 in 87 days.<ref name="Tau4AAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34971 |title=Tau4 Serpentis |author1=VSX |last2=Otero |first2=S. A|date=28 June 2012 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=24 June 2014}}</ref> This star has been found to display an inverse [[P Cygni profile]],<ref name="Kolotilov">{{cite journal |last1=Kolotilov |first1=E. A. |last2=Russev |first2=R. M. |title=Inverse P Cyg Profile of Halpha in the Spectrum of the Red Giant HD 139216 = tau4 Ser |journal=Information Bulletin on Variable Stars |volume=1730 |page=1 |date=January 1980 |bibcode=1980IBVS.1730....1K}}</ref> where cold infalling gas on to the star creates [[redshift]]ed hydrogen absorption lines next to the normal emission lines.<ref name="UToledo">{{cite web|url=http://astro1.physics.utoledo.edu/~megeath/ph6820/lecture7_ph6820.pdf |title=Lecture 7: The Collapse of Cores and Infall |author=Galactic Star and Planet Formation Research Group |publisher=Department of Physics and Astronomy, University of Toledo |access-date=17 July 2015}}</ref>

Several stars in Serpens have been found to have [[exoplanet|planets]]. The brightest, [[Omega Serpentis]], located between Epsilon and Mu, is an [[orange giant]] with a planet of at least 1.7 [[Jupiter]]-masses.<ref name="Sato">{{Cite journal | doi = 10.1093/pasj/65.4.85| title = Planetary Companions to Three Evolved Intermediate-Mass Stars: HD 2952, HD 120084, and ω Serpentis| journal = Publications of the Astronomical Society of Japan| volume = 65| issue = 4| pages = 85| year = 2013| last1 = Sato | first1 = B.| last2 = Omiya | first2 = M.| last3 = Harakawa | first3 = H.| last4 = Liu | first4 = Y. -J. | last5 = Izumiura | first5 = H.| last6 = Kambe | first6 = E.| last7 = Takeda | first7 = Y.| last8 = Yoshida | first8 = M.| last9 = Itoh | first9 = Y.| last10 = Ando | first10 = H.| last11 = Kokubo | first11 = E.| last12 = Ida | first12 = S.| bibcode = 2013PASJ...65...85S|arxiv = 1304.4328 | s2cid = 119248666}}</ref> [[NN Serpentis]], an eclipsing [[Post common envelope binary|post-common-envelope binary]] consisting of a [[white dwarf]] and a [[red dwarf]],<ref name="Parsons">{{Cite journal | doi = 10.1111/j.1365-2966.2009.16072.x| title = Precise mass and radius values for the white dwarf and low mass M dwarf in the pre-cataclysmic binary NN Serpentis| journal = Monthly Notices of the Royal Astronomical Society| volume = 402| issue = 4| pages = 2591| year = 2010| last1 = Parsons | first1 = S. G.| last2 = Marsh | first2 = T. R.| last3 = Copperwheat | first3 = C. M.| last4 = Dhillon | first4 = V. S.| last5 = Littlefair | first5 = S. P.| last6 = Gänsicke | first6 = B. T.| last7 = Hickman | first7 = R.| doi-access = free| bibcode = 2010MNRAS.402.2591P|arxiv = 0909.4307 | s2cid = 15186725}}</ref> is very likely to have two planets causing variations in the period of the eclipses.<ref name="Marsh">{{Cite journal | doi = 10.1093/mnras/stt1903| title = The planets around NN Serpentis: Still there| journal = Monthly Notices of the Royal Astronomical Society| volume = 437| issue = 1| pages = 475| year = 2013| last1 = Marsh | first1 = T. R.| last2 = Parsons | first2 = S. G.| last3 = Bours | first3 = M. C. P.| last4 = Littlefair | first4 = S. P.| last5 = Copperwheat | first5 = C. M.| last6 = Dhillon | first6 = V. S.| last7 = Breedt | first7 = E.| last8 = Caceres | first8 = C.| last9 = Schreiber | first9 = M. R.| doi-access = free| bibcode = 2014MNRAS.437..475M|arxiv = 1310.1391 | s2cid = 53954504| url = http://wrap.warwick.ac.uk/58930/1/WRAP_MNRAS-2014-Marsh-475-88.pdf}}</ref> Although it does not have a planet, the solar analog [[HD 137510]] has been found to have a [[brown dwarf]] companion within the [[brown-dwarf desert]].<ref name="Endl">{{cite journal|doi=10.1086/422310|title=HD 137510: An Oasis in the Brown Dwarf Desert|journal=The Astrophysical Journal|volume=611|issue=2|pages=1121–1124|year=2004|last1=Endl|first1=Michael|last2=Hatzes|first2=Artie P.|last3=Cochran|first3=William D.|last4=McArthur|first4=Barbara|last5=Prieto|first5=Carlos Allende|last6=Paulson|first6=Diane B.|last7=Guenther|first7=Eike|last8=Bedalov|first8=Ana|bibcode=2004ApJ...611.1121E|arxiv = astro-ph/0404584 |s2cid=119062344}}</ref>

[[PSR B1534+11]] is a system consisting of two [[neutron star]]s orbiting each other, one of which is a [[pulsar]] with a period of 37.9 milliseconds. Situated approximately 1000 parsecs distant, the system was used to test [[Albert Einstein]]'s theory of [[general relativity]], validating the system's relativistic parameters to within 0.2% of values predicted by the theory.<ref name="Fonseca">{{Cite journal | doi = 10.1088/0004-637X/787/1/82| title = A Comprehensive Study of Relativistic Gravity Using PSR B1534+12| journal = The Astrophysical Journal| volume = 787| issue = 1| pages = 82| year = 2014| last1 = Fonseca | first1 = E. | last2 = Stairs | first2 = I. H. | last3 = Thorsett | first3 = S. E. | bibcode =  2014ApJ...787...82F|arxiv = 1402.4836 | s2cid = 119198979}}</ref> The [[X-ray]] emission from the system has been found to be present when the non-pulsar star intersects the equatorial [[pulsar wind]] of the pulsar, and the system's orbit has been found to vary slightly.<ref name="Durant">{{Cite journal | doi = 10.1088/0004-637X/741/1/65| title = Orbital Variation of the X-Ray Emission from the Double Neutron Star Binary J1537+1155| journal = The Astrophysical Journal| volume = 741| issue = 1| pages = 65| year = 2011| last1 = Durant | first1 = M. | last2 = Kargaltsev | first2 = O. | last3 = Volkov | first3 = I. | last4 = Pavlov | first4 = G. G. | bibcode = 2011ApJ...741...65D|arxiv = 1108.3330 | s2cid = 119200269}}</ref>

====Tail stars====
[[File:SerpensCaudaCC.jpg|thumb|left|200px|The constellation Serpens (Cauda) as it can be seen by the naked eye|alt=The pattern of stars in Serpens Cauda seen with the naked eye, with a line of stars marking the tail]]
The brightest star in the tail, [[Eta Serpentis]], is similar to Alpha Serpentis' primary in that it is a red giant of spectral class K. This star, however, is known to exhibit solar-like oscillations over a period of approximately 2.16 hours.<ref name="Hekker">{{Cite journal | doi = 10.1051/0004-6361/200912777| title = Line-profile variations of stochastically excited oscillations in four evolved stars| journal = Astronomy and Astrophysics| volume = 515| pages = A43| year = 2010| last1 = Hekker | first1 = S.| last2 = Aerts | first2 = C.| bibcode = 2010A&A...515A..43H|arxiv = 1002.2212 | s2cid = 30911563}}</ref><ref name=mnras409_2_777>{{citation | display-authors=1 | last1=Tabur | first1=V. | last2=Bedding | first2=T. R. | last3=Kiss | first3=L. L. | last4=Giles | first4=T. | last5=Derekas | first5=A. | last6=Moon | first6=T. T. | title=Period-luminosity relations of pulsating M giants in the solar neighbourhood and the Magellanic Clouds | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=409 | issue=2 | pages=777–788 |date=December 2010 | doi=10.1111/j.1365-2966.2010.17341.x | doi-access=free | bibcode=2010MNRAS.409..777T |arxiv = 1007.2974 | s2cid=118411237 }}</ref> The other two stars in Serpens Cauda forming its asterism are [[Theta Serpentis|Theta]] and [[Xi Serpentis]]. Xi, where the asterism crosses over to Mu Serpentis in the head, is a triple star system<ref name="Eggleton"/> located approximately 105 parsecs away.<ref name="XiSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=ksi+ser |title = Xi Serpentis – Spectroscopic binary|publisher = SIMBAD | access-date = 21 June 2014}}</ref><ref name=XiSpecType>{{citation
 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J.
 | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T.
 | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E.
 | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R.
 | title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample
 | journal=[[The Astronomical Journal]] | display-authors=1
 | volume=132 | issue=1 | pages=161–170 | date=July 2006
 | doi=10.1086/504637 | bibcode=2006AJ....132..161G
 | arxiv=astro-ph/0603770 | s2cid=119476992 | postscript=. }}</ref> Two of the stars, with a combined apparent magnitude of around 3.5, form a spectroscopic binary with an [[angular separation]] of only 2.2 milli[[arcseconds]],<ref name="Halbwachs">{{cite journal|last=Halbwachs|first=J. L.|title=List of Estimated Angular Separations of Spectroscopic Binaries|journal=Astronomy and Astrophysics Supplement|volume=44|page=47|year=1981|bibcode=1981A&AS...44...47H}}</ref> and thus cannot be resolved with modern equipment. The primary is a [[white giant]] with an excess of [[strontium]].<ref name="XiSimbad"/> Theta, forming the tip of the tail, is also a multiple system, consisting of two A-type main-sequence stars with a combined apparent magnitude of around 4.1 separated by almost half an arcminute.<ref name="Eggleton"/> There is also a third G-type star with a mass and radius similar to that of the Sun.<ref name=ThetaSerC>{{cite journal
 | display-authors=1
 | last1=Boyajian | first1=Tabetha S. | last2=von Braun | first2=Kaspar
 | last3=van Belle | first3=Gerard | last4=Farrington | first4=Chris
 | last5=Schaefer | first5=Gail | last6=Jones | first6=Jeremy
 | last7=White | first7=Russel | last8=McAlister | first8=Harold A.
 | last9=ten Brummelaar | first9=Theo A. | last10=Ridgway | first10=Stephen
 | last11=Gies | first11=Douglas | last12=Sturmann | first12=Laszlo
 | last13=Sturmann | first13=Judit | last14=Turner | first14=Nils H.
 | last15=Goldfinger | first15=P. J. | last16=Vargas | first16=Norm
 | title=Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations
 | journal=The Astrophysical Journal | volume=771 | issue=1
 | id=40 | pages=31 | date=July 2013
 | arxiv=1306.2974 | doi=10.1088/0004-637X/771/1/40
 | bibcode=2013ApJ...771...40B | s2cid=14911430 }} See Table 3.</ref>

Lying near the boundary with Ophiuchus are [[Zeta Serpentis|Zeta]], [[Nu Serpentis|Nu]], and [[Omicron Serpentis]]. All three are 4th-magnitude main-sequence stars, with Nu and Omicron being of spectral type A<ref name="NuSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=*+nu.+ser |title = Nu Serpentis – Star in double system|publisher = SIMBAD | access-date = 20 June 2014}}</ref><ref name="OmicronSimbad">{{cite news |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=omi+ser |title = Omicron Serpentis – Variable Star of delta Sct type|publisher = SIMBAD | access-date = 20 June 2014}}</ref> and Zeta being of spectral type F.<ref name="ZetaSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=zet+ser |title = Zeta Serpentis – Star|publisher = SIMBAD | access-date = 20 June 2014}}</ref> Nu is a single star<ref name="Eggleton"/> with a 9th-magnitude visual companion,<ref name="NuBSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+156928B |title = BD-12 4724 – Star in double system|publisher = SIMBAD | access-date = 20 June 2014}}</ref> while Omicron is a Delta Scuti variable with amplitude variations of 0.01 magnitudes.<ref name="OmicronAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34970 |title=Omicron Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=20 June 2014}}</ref> In 1909, the [[symbiotic nova]]<ref name="Pavlenko">{{Cite journal | doi = 10.1007/BF02044949| title = 9,6-Year periodicity of symbiotic nova RT Ser (1909) during the outburst decay from 1940 to 1994| journal = Astrophysics| volume = 39| issue = 1| pages = 15–19| year = 1996| last1 = Pavlenko | first1 = E. P.| last2 = Bochkov | first2 = V. V.| last3 = Vasil'yanovskaya | first3 = O. P.| bibcode = 1996Ap.....39...15P| s2cid = 120532937}}</ref> [[RT Serpentis]] appeared near Omicron, although it only reached a maximum magnitude of 10.<ref name="RTAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34603 |title=RT Serpentis |author1=VSX |last2=Osborne |first2=W. |date=1 April 2014 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=28 May 2014}}</ref>

The star system [[59 Serpentis]], also known as d Serpentis, is a triple star system <ref name="Tilley">{{Cite journal | doi = 10.1086/144577| title = A Spectrographic Study of the Triple System in 59 D Serpentis| journal = The Astrophysical Journal| volume = 98| pages = 347| year = 1943| last1 = Tilley | first1 = E. C. | bibcode = 1943ApJ....98..347T}}</ref> consisting of a spectroscopic binary containing an A-type star and an orange giant<ref name="Abt">{{Cite journal | doi = 10.1088/0067-0049/180/1/117| title = MK Classifications of Spectroscopic Binaries| journal = The Astrophysical Journal Supplement Series| volume = 180| issue = 1| pages = 117–118| year = 2009| last1 = Abt | first1 = H. A. | bibcode = 2009ApJS..180..117A| s2cid = 122811461}}</ref> and an orange giant secondary.<ref name="59BSimbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+169986 |title = HD 169986 – Star in double system|publisher = SIMBAD | access-date = 25 May 2014}}</ref> The system shows [[irregular variable|irregular variations in brightness]] between magnitudes 5.17 and 5.2.<ref name="59AAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34973 |title=d Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=25 May 2014}}</ref> In 1970, the nova [[FH Serpentis]] appeared just slightly north of 59 Serpentis, reaching a maximum brightness of 4.5.<ref name="FHAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34763 |title=FH Serpentis |author=VSX |date=28 April 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=23 June 2014}}</ref> Also near 59 Serpentis in the [[Serpens Cloud]] are several [[Orion variable]]s. [[MWC 297]] is a [[Herbig Ae/Be star|Herbig Be star]] that in 1994 exhibited a large [[X-ray]] flare and increased in X-ray luminosity by five times before returning to the quiescent state.<ref name="Hamaguchi">{{Cite journal | doi = 10.1086/308607| title = Large X-Ray Flare from the Herbig Be Star MWC 297| journal = The Astrophysical Journal| volume = 532| issue = 2| pages = 1111| year = 2000| last1 = Hamaguchi | first1 = K. | last2 = Terada | first2 = H. | last3 = Bamba | first3 = A. | last4 = Koyama | first4 = K. | bibcode = 2000ApJ...532.1111H|arxiv = astro-ph/9911120 | s2cid = 1508384}}</ref> The star also appears to possess a [[circumstellar disk]].<ref name="Acke">{{Cite journal | doi = 10.1051/0004-6361:200809654| title = MWC&nbsp;297: A young high-mass star rotating at critical velocity| journal = Astronomy and Astrophysics| volume = 485| pages = 209–221| year = 2008| last1 = Acke | first1 = B.| last2 = Verhoelst | first2 = T.| last3 = van den Ancker | first3 = M. E.| last4 = Deroo | first4 = P.| last5 = Waelkens | first5 = C.| last6 = Chesneau | first6 = O.| last7 = Tatulli | first7 = E.| last8 = Benisty | first8 = M.| last9 = Puga | first9 = E.| last10 = Waters | first10 = L. B. F. M.| last11 = Verhoeff | first11 = A.| last12 = de Koter | first12 = A.| issue = 1| bibcode = 2008A&A...485..209A|arxiv = 0804.1212 | s2cid = 4794509}}</ref> Another Orion variable in the region is [[VV Serpentis]], a Herbig Ae star that has been found to exhibit Delta Scuti pulsations.<ref name="Ripepi">{{Cite journal | doi = 10.1051/0004-6361:20065728| title = Discovery of δ Scuti pulsation in the Herbig Ae star VV Serpentis| journal = Astronomy and Astrophysics| volume = 462| issue = 3| pages = 1023| year = 2007| last1 = Ripepi | first1 = V.| last2 = Bernabei | first2 = S.| last3 = Marconi | first3 = M.| last4 = Ruoppo | first4 = A.| last5 = Palla | first5 = F.| last6 = Monteiro | first6 = M. J. P. F. G.| last7 = Marques | first7 = J. P.| last8 = Ferrara | first8 = P.| last9 = Marinoni | first9 = S.| last10 = Terranegra | first10 = L.| bibcode = 2007A&A...462.1023R|arxiv = astro-ph/0610194 | s2cid = 16241531}}</ref> VV Serpentis has also, like MWC 297, been found to have a dusty disk surrounding it,<ref name="Alonso-Albi">{{Cite journal | doi = 10.1086/587935| title = The Dusty Disk around VV Serpens| journal = The Astrophysical Journal| volume = 680| issue = 2| pages = 1289–1294| year = 2008| last1 = Alonso-Albi | first1 = T.| last2 = Fuente | first2 = A.| last3 = Bachiller | first3 = R.| last4 = Neri | first4 = R.| last5 = Planesas | first5 = P.| last6 = Testi | first6 = L.| bibcode = 2008ApJ...680.1289A|arxiv = 0802.4152 | s2cid = 118405939}}</ref> and is also a [[UX Orionis star]],<ref name="VVAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34631 |title=VV Serpentis |author1=VSX |last2=Otero |first2=S. A. |date=23 November 2011 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=28 May 2014}}</ref> meaning that it shows irregular variations in its brightness.<ref>{{cite book|editor1-last=Ridpath|editor1-first=Ian|title=A dictionary of astronomy|date=2012|publisher=Oxford University Press|location=Oxford|isbn=9780191739439|edition=2|chapter-url=http://www.oxfordreference.com/view/10.1093/oi/authority.20110803115022152|access-date=8 August 2015|chapter=UX Orionis star|doi=10.1093/acref/9780199609055.001.0001}}</ref>

The star [[HR 6958]], also known as MV Serpentis, is an Alpha<sup>2</sup> Canum Venaticorum variable that is faintly visible to the naked eye.<ref name="MVAAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=34875 |title=MV Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=25 May 2014}}</ref> The star's metal abundance is ten times higher than the Sun for most metals at the iron peak and up to 1,000 times more for heavier elements. It has also been found to contain excess [[silicon]].<ref name="Lopez-Garcia">{{Cite journal | doi = 10.1051/0004-6361:20000438| title = Elemental abundance studies of CP stars
| journal = Astronomy and Astrophysics| volume = 367| issue = 3| pages = 859–864| year = 2001| last1 = López-García| first1 = Z.| last2 = Adelman | first2 = S. J. | last3 = Pintado | first3 = O. I.|bibcode=2001A&A...367..859L| doi-access = free}}</ref> Barely visible to the naked eye is [[HD 172365]],<ref name="HD172365Simbad">{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+172365 |title = HR 7008 – Star in Cluster|publisher = SIMBAD | access-date = 14 December 2014}}</ref> a likely post-[[blue straggler]] in the open cluster [[IC 4756]] that contains a large excess of [[lithium]].<ref name="Andrievsky">{{cite journal |last1=Andrievsky |first1=S. M. |last2=Gorlova |first2=N. I. |last3=Klochkova |first3=V. G. |last4=Kovtyuch |first4=V. V. |last5=Panchuk |first5=V. E. |title=The Lithium-rich supergiant HD172365 |journal=Astronomische Nachrichten |volume=320 |issue=1 |pages=35–41 |year=1999 |bibcode=1999AN....320...35A |doi=10.1002/1521-3994(199903)320:1<35::aid-asna35>3.0.co;2-f}}</ref> [[HD 172189]], also located in IC 4756, is an [[Algol variable]] eclipsing binary<ref name="Ibanoglu">{{Cite journal
 | doi = 10.1111/j.1365-2966.2008.14087.x
| title = Spectroscopic and photometric observations of the selected Algol-type binaries - IV. V799 Cassiopeiae, BX Piscium and HD 172189| journal = Monthly Notices of the Royal Astronomical Society| volume = 392| issue = 2| pages = 757| year = 2009| last1 = Ibanoǧlu | first1 = C.| last2 = Evren | first2 = S.| last3 = Taş | first3 = G.| last4 = Çakırlı | first4 = Ö.| last5 = Bozkurt | first5 = Z.| last6 = Afşar | first6 = M.| last7 = Sipahi | first7 = E.| last8 = Dal | first8 = H. A.| last9 = Özdarcan | first9 = O.| last10 = Çamurdan | first10 = D. Z. | last11 = Çamurdan | first11 = M.| last12 = Frasca | first12 = A.| bibcode = 2009MNRAS.392..757I| doi-access = free}}</ref> with a 5.70 day period. The primary star in the system is also a Delta Scuti variable, undergoing multiple pulsation frequencies, which, combined with the eclipses, causes the system to vary by around a tenth of a magnitude.<ref name="Costa">{{Cite journal | doi = 10.1051/0004-6361:20065784| title = Pulsational frequencies of the eclipsing δ&nbsp;Scuti star HD&nbsp;172189. Results of the STEPHI XIII campaign| journal = Astronomy and Astrophysics| volume = 468| issue = 2| pages = 637–642| year = 2007| last1 = Costa | first1 = J. E. S.| last2 = Michel | first2 = E.| last3 = Peña | first3 = J.| last4 = Creevey | first4 = O.| last5 = Li | first5 = Z. P.| last6 = Chevreton | first6 = M.| last7 = Belmonte | first7 = J. A.| last8 = Alvarez | first8 = M.| last9 = Fox Machado | first9 = L.| last10 = Parrao | first10 = L.| last11 = Pérez Hernéndez | first11 = F.| last12 = Fernández | first12 = A.| last13 = Fremy | first13 = J. R.| last14 = Pau | first14 = S.| last15 = Alonso | first15 = R.| bibcode = 2007A&A...468..637C|arxiv = 0706.4083 }}</ref>

As the [[galactic plane]] passes through it, Serpens Cauda contains many massive [[OB star]]s. Several of these are visible to the naked eye, such as [[NW Serpentis]], an early [[Be star]] that has been found to be somewhat variable. The variability is interesting; according to one study, it could be one of the first discovered hybrids between [[Beta Cephei variable]]s and slowly pulsating B stars.<ref name="Gutierrez-Soto">{{Cite journal | doi = 10.1051/0004-6361:20077414| title = Multiperiodic pulsations in the Be stars NW&nbsp;Serpentis and V1446&nbsp;Aquilae| journal = Astronomy and Astrophysics| volume = 472| issue = 2| pages = 565–570| year = 2007| last1 = Gutiérrez-Soto | first1 = J.| last2 = Fabregat | first2 = J.| last3 = Suso | first3 = J.| last4 = Suárez | first4 = J. C.| last5 = Moya | first5 = A.| last6 = Garrido | first6 = R.| last7 = Hubert | first7 = A. -M. | last8 = Floquet | first8 = M.| last9 = Neiner | first9 = C.| last10 = Frémat | first10 = Y.| bibcode = 2007A&A...472..565G| doi-access = free| hdl = 10550/15993| hdl-access = free}}</ref> Although not visible to the naked eye, [[HD 167971]] (MY Serpentis) is a [[Beta Lyrae variable]] triple system consisting of three very hot [[O-type star]]s. A member of the cluster [[NGC 6604]],<ref name="DeBecker">{{Cite journal | doi = 10.1051/0004-6361:20052810| title = An XMM-Newton observation of the multiple system HD 167971 (O5-8V + O5-8V + (O8I)) and the young open cluster NGC 6604| journal = Astronomy and Astrophysics| volume = 437| issue = 3| pages = 1029–1046| year = 2005| last1 = De Becker | first1 = M.| last2 = Rauw | first2 = G.| last3 = Blomme | first3 = R.| last4 = Pittard | first4 = J. M.| last5 = Stevens | first5 = I. R.| last6 = Runacres | first6 = M. C.| bibcode = 2005A&A...437.1029D|arxiv = astro-ph/0503471 | s2cid = 16980385}}</ref> the two eclipsing stars are both blue giants, with one being of the very early spectral type O7.5III. The remaining star is either a blue giant or [[blue supergiant|supergiant]] of a late O or early B spectral type.<ref name="Ibanoglu2">{{Cite journal | doi = 10.1093/mnras/stt1616| title = MY Serpentis: A high-mass triple system in the Ser OB2 association| journal = Monthly Notices of the Royal Astronomical Society| volume = 436| issue = 1| pages = 750–758| year = 2013| last1 = Ibanoglu | first1 = C.| last2 = Cakirli | first2 = O.| last3 = Sipahi | first3 = E.| doi-access = free|arxiv = 1308.4971 |bibcode = 2013MNRAS.436..750I | s2cid = 119246895}}</ref> Also an eclipsing<ref name="V411AAVSO">{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=62762 |title=V411 Serpentis |author=VSX |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=25 May 2014}}</ref> binary, the [[HD 166734]] system consists of two O-type blue supergiants in orbit around each other.<ref name="Conti">{{Cite journal | doi = 10.1086/157971| title = Spectroscopic studies of O-type binaries. V - the Of System HD 166734| journal = The Astrophysical Journal| volume = 238| pages = 184| year = 1980| last1 = Conti | first1 = P. S.| last2 = Ebbets | first2 = D.| last3 = Massey | first3 = P.| last4 = Niemela | first4 = V. S.| bibcode = 1980ApJ...238..184C}}</ref> Less extreme in terms of mass and temperature is [[HD 161701]], a spectroscopic binary consisting of a [[B-type star|B-type]] primary and an [[Ap star|Ap]] secondary, although it is the only known spectroscopic binary to consist of a star with excess of [[mercury (element)|mercury]] and [[manganese]] and an Ap star.<ref name="Hubrig">{{cite journal|doi=10.1093/mnrasl/slu012|title=The magnetic field in HD 161701, the only binary system identified to consist of an Hg ''Mn'' primary and an Ap secondary|journal=Monthly Notices of the Royal Astronomical Society: Letters|volume=440|pages=L6–L10|year=2014|last1=Hubrig|first1=S.|last2=Carroll|first2=T. A.|last3=Gonzalez|first3=J. F.|last4=Scholler|first4=M.|last5=Ilyin|first5=I.|last6=Saffe|first6=C.|last7=Castelli|first7=F.|last8=Leone|first8=F.|last9=Giarrusso|first9=M.|bibcode=2014MNRAS.440L...6H|doi-access=free|hdl=11336/4902|hdl-access=free}}</ref>

South of the [[Eagle Nebula]] on the border with Sagittarius is the eclipsing binary [[W Serpentis]], whose primary is a white giant that is interacting with the secondary. The system has been found to contain an [[accretion disk]], and was one of the first discovered [[Serpentid]]s, which are eclipsing binaries containing exceptionally strong [[far-ultraviolet]] spectral lines.<ref name="Weiland">{{Cite journal | doi = 10.1086/175883| title = Goddard High-Resolution Spectrograph Observations of the Interacting Binary System W Serpentis| journal = The Astrophysical Journal| volume = 447| pages = 401| year = 1995| last1 = Weiland | first1 = J. L.| last2 = Shore | first2 = S. N.| last3 = Beaver | first3 = E. A.| last4 = Lyons | first4 = R. W.| last5 = Rosenblatt | first5 = E. I.| bibcode = 1995ApJ...447..401W}}</ref> It is suspected that such Serpentids are in an earlier evolutionary phase, and will evolve first into [[double periodic variable]]s and then classical Algol variables.<ref name="Mennickent">{{cite journal|arxiv=0904.1539|last1= Mennickent|first1= R. E.|title= Interacting Binary Star Environments and the W Ser - DPV - Algol Connection|last2=  Kolaczkowski|first2= Z.|year= 2009|bibcode=2010RMxAC..38...23M|volume=38|pages=23–26|journal=The Interferometric View on Hot Stars}}
</ref> Also near the Eagle Nebula is the eclipsing [[Wolf–Rayet star|Wolf–Rayet]] binary [[CV Serpentis]], consisting of a Wolf–Rayet star and a hot O-type subgiant. The system is surrounded by a ring-shaped [[nebula]], likely formed during the Wolf–Rayet phase of the primary.<ref name="Cappa">{{cite journal | doi = 10.1086/340725 | title=VLA Radio Continuum and IRAS Observations of the Ring Nebulae around WR 101 and WR 113 | journal=The Astronomical Journal | date=2002 | volume=123 | issue=6 | pages=3348–3355 | first=C. E. | last=Cappa | bibcode=2002AJ....123.3348C| doi-access=free }}</ref> The eclipses of the system vary erratically, and although there are two theories as to why, neither of them is completely consistent with current understanding of stars.<ref name="David-Uraz">{{cite journal | doi = 10.1111/j.1365-2966.2012.21736.x | title= Using MOST to reveal the secrets of the mischievous Wolf-Rayet binary CV Ser | journal=Monthly Notices of the Royal Astronomical Society | date=2012 | volume=426 | issue=3 | pages=1720–1730 | first=Alexandre | last=David-Uraz | doi-access= free | bibcode=2012MNRAS.426.1720D|arxiv = 1207.6032 }}</ref>

Serpens Cauda contains a few [[X-ray binary|X-ray binaries]]. One of these, [[GX 17+2]], is a [[low-mass X-ray binary]] consisting of a neutron star and, as in all low-mass X-ray binaries, a low-mass star. The system has been classified as a [[Z source|Sco-like Z source]], meaning that its accretion is near the [[Eddington limit]].<ref name="Lin">{{cite journal | doi = 10.1088/0004-637X/756/1/34 | title=The Spectral Evolution Along the Z Track of the Bright Neutron Star X-Ray Binary GX 17+2 | journal=The Astrophysical Journal | date=2012 | volume=756 | issue=1 | pages=34 | first=Dacheng | last=Lin | bibcode=2012ApJ...756...34L|arxiv = 1207.1107 | s2cid=10083273 }}</ref> The system has also been found to approximately every 3 days brighten by around 3.5 [[Apparent magnitude#Standard reference values|K-band]] magnitudes, possibly due to the presence of a [[synchrotron radiation|synchrotron jet]].<ref name="Bornak">{{cite journal | doi = 10.1088/0004-637X/701/2/L110 | title= A Possible Period for the K-Band Brightening Episodes of GX 17+2 | journal=The Astrophysical Journal | date=2009 | volume=701 | issue=2 | pages=L110–L113 | first=Jillian | last=Bornak | bibcode=2009ApJ...701L.110B|arxiv = 0907.4348 | s2cid= 18361338 }}</ref> Another low-mass X-ray binary, [[Serpens X-1]], undergoes occasional X-ray bursts. One in particular lasted nearly four hours, possibly explained by the burning of carbon in "a heavy element ocean".<ref name="Cornelisse">{{cite journal | doi = 10.1051/0004-6361:20011591 | title=A four-hours long burst from Serpens X-1 | journal=Astronomy and Astrophysics | date=2002 | volume=382 | issue=1 | pages=174–177 | first=R. | last=Cornelisse | bibcode=2002A&A...382..174C|arxiv = astro-ph/0111263 | s2cid=16830958 }}</ref>

Φ 332 (Finsen 332) is a tiny and difficult double-double star at 18:45 / +5°30', named '''Tweedledee and Tweedledum''' by South African astronomer [[William Stephen Finsen]], who was struck by the nearly identical position angles and separations at the time of his 1953 discovery.<ref>Sky Catalogue 2000.0, Volume 2: Double Stars, Variable Stars, and Nonstellar Objects (edited by Alan Hirshfeld and Roger W. Sinnott, 1985), Chapter 3: Glossary of Selected Astronomical Names.</ref><ref>Sky and Telescope, November 1961, page 263.</ref><ref>Deep-Sky Name Index 2000.0 - Hugh C. Maddocks (Foxon-Maddocks Associates, 1991).</ref> [[Gliese 710]] is a star that is expected to pass very close to the Solar System in around 1.29 million years.<ref name="Bailer2018">{{cite journal|last1=Bailer-Jones|first1=C.A.L.
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