Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Published:https://doi.org/10.1098/rsta.2009.0254

    Many, possibly most, stars form in binary and higher order multiple systems. Therefore, the properties and frequency of binary systems provide strong clues to the star-formation process, and constraints on star-formation models. However, the majority of stars also form in star clusters in which the birth binary properties and frequency can be altered rapidly by dynamical processing. Thus, we almost never see the birth population, which makes it very difficult to know whether star formation (as traced by binaries, at least) is universal or whether it depends on the environment. In addition, the field population consists of a mixture of systems from different clusters that have all been processed in different ways.

    References

    • Abt H. A.. 1983Normal and abnormal binary frequencies. Annu. Rev. Astron. Astrophys. 21, 343-372(doi:10.1146/annurev.aa.21.090183.002015). Crossref, ISIGoogle Scholar
    • Ahmic M., Jayawardhana R., Brandeker A., Scholz A., van Kerkwijk M. H., Delgado Donate E.& Froebrich D.. 2007Multiplicity among young brown dwarfs and very low mass stars. Astrophys. J. 671, 2074-2081(doi:10.1086/522875). Crossref, ISIGoogle Scholar
    • Allison R. J., Goodwin S. P., Parker R. J., de Grijs R., Portegies Zwart S. F.& Kouwenhoven M. B. N.. 2009Dynamical mass segregation on a very short timescale. Astrophys. J. 700, L99-L103(doi:10.1088/0004-637X/700/2/L99). Crossref, ISIGoogle Scholar
    • Alves J., Lombardi M.& Lada C. J.. 2007The mass function of dense molecular cores and the origin of the IMF. Astron. Astrophys. 462, L17-L21(doi:10.1051/0004-6361:20066389). Crossref, ISIGoogle Scholar
    • Anosova J. P.. 1986Dynamical evolution of triple systems. Astrophys. Space Sci. 124, 217-241(doi:10.1007/BF00656037). Crossref, ISIGoogle Scholar
    • Basri G.& Reiners A.. 2006A survey for spectroscopic binaries among very low mass stars. Astron. J. 132, 663-675(doi:10.1086/505198). Crossref, ISIGoogle Scholar
    • Bastian N., Gieles M., Goodwin S. P., Trancho G., Smith L. J., Konstantopoulos I.& Efremov Yu.. 2008The early expansion of cluster cores. Mon. Not. R. Astron. Soc. 389, 223-230(doi:10.1111/j.1365-2966.2008.13547.x). Crossref, ISIGoogle Scholar
    • Binney J.& Tremaine S.. 1987Galactic dynamicsPrinceton, NJPrinceton University Press. Google Scholar
    • Bouy H., Martín E. L., Brandner W., Zapatero-Osorio M. R., Béjar V. J. S., Schirmer M., Huélamo N.& Ghez A. M.. 2006Multiplicity of very low-mass objects in the Upper Scorpius OB association:a possible wide binary population. Astron. Astrophys. 451, 177-186(doi:10.1051/0004-6361:20054252). Crossref, ISIGoogle Scholar
    • Brandeker A., Jayawardhana R.& Najita J.. 2003Keck adaptive optics imaging of nearby young stars:detection of close multiple systems. Astron. J. 126, 2009-2014(doi:10.1086/378057). Crossref, ISIGoogle Scholar
    • Brandeker A., Jayawardhana R., Khavari P., Haisch K. E.& Mardones D.. 2006Deficit of wide binaries in the η Chamaeleontis young cluster. Astrophys. J. 652, 1572-1584(doi:10.1086/508483). Crossref, ISIGoogle Scholar
    • Burgasser A. J., Kirkpatrick J. D.& Lowrance P. J.. 2005Multiplicity among widely separated brown dwarf companions to nearby stars:Gliese 337CD. Astron. J. 129, 2849-2855(doi:10.1086/430218). Crossref, ISIGoogle Scholar
    • Burgasser A. J., Reid I. N., Siegler N., Close L., Allen P., Lowrance P.& Gizis J.. 2007Not alone:tracing the origins of very-low-mass stars and brown dwarfs through multiplicity studies. Protostars and planets V(eds , Reipurth B., Jewitt D.& Keil K.)427-441Tuscon, AZUniversity of Arizona Press. Google Scholar
    • Clarke C.. 2010The physics and modes of star cluster formation:simulations. Phil. Trans. R. Soc. A 368, 733-754(doi:10.1098/rsta.2009.0262). Link, ISIGoogle Scholar
    • Close L. M., Siegler N., Freed M.& Biller B.. 2003Detection of nine M8.0–L0.5 binaries:the very low mass binary population and its implications for brown dwarf and very low mass star formation. Astrophys. J. 587, 407-422(doi:10.1086/368177). Crossref, ISIGoogle Scholar
    • Connelley M. S., Reipurth B.& Tokunaga A. T.. 2008The evolution of the multiplicity of embedded protostars. II. Binary separation distribution and analysis. Astron. J. 135, 2526-2536. Crossref, ISIGoogle Scholar
    • Correia S., Zinnecker H., Ratzka Th.& Sterzik M. F.. 2006VLT/NACO survey for triple and quadruple systems among visual pre-main sequence binaries. Astron. Astrophys. 459, 909-926(doi:10.1051/0004-6361:20065545). Crossref, ISIGoogle Scholar
    • Crowther P. A., Hadfield L. J., Clark J. S., Negueruela I.& Vacca W. D.. 2006A census of the Wolf–Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy. Mon. Not. R. Astron. Soc. 372, 1407-1424(doi:10.1111/j.1365-2966.2006.10952.x). Crossref, ISIGoogle Scholar
    • de Grijs R.. 2010A revolution in star cluster research:setting the scene. Phil. Trans. R. Soc. A 368, 693-711(doi:10.1098/rsta.2009.0253). Link, ISIGoogle Scholar
    • Delgado Donate E. J., Clarke C. J., Bate M. R.& Hodgkin S. T.. 2004On the properties of young multiple stars. Mon. Not. R. Astron. Soc. 351, 617-629(doi:10.1111/j.1365-2966.2004.07803.x). Crossref, ISIGoogle Scholar
    • Duchêne G.. 1999Binary fraction in low-mass star forming regions:a re-examination of the possible excesses and implications. Astron. Astrophys. 341, 547-552. ISIGoogle Scholar
    • Duchêne G., Bouvier J.& Simon T.. 1999Low-mass binaries in the young cluster IC 348:implications for binary formation and evolution. Astron. Astrophys. 343, 831-840. ISIGoogle Scholar
    • Duchêne G., Bouvier J., Bontemps S., André P.& Motte F.. 2004Multiple protostellar systems. I. A deep near-infrared survey of Taurus and Ophiuchus protostellar objects. Astron. Astrophys. 427, 651-665. Crossref, ISIGoogle Scholar
    • Duchêne G., Bontemps S., Bouvier J., André P., Djupvik A. A.& Ghez A. M.. 2007Multiple protostellar systems. II. A high resolution near-infrared imaging survey in nearby star-forming regions. Astron. Astrophys. 476, 229-242. Crossref, ISIGoogle Scholar
    • Duquennoy A.& Mayor M.. 1991Multiplicity among solar-type stars in the solar neighbourhood. II. Distribution of the orbital elements in an unbiased sample. Astron. Astrophys. 248, 485-524. ISIGoogle Scholar
    • Eggleton P. P.& Tokovinin A. A.. 2008A catalogue of multiplicity among bright stellar systems. Mon. Not. R. Astron. Soc. 389, 869-879(doi:10.1111/j.1365-2966.2008.13596.x). Crossref, ISIGoogle Scholar
    • Fischer D. A.& Marcy G. W.. 1992Multiplicity among M dwarfs. Astron. J. 396, 178-194. Crossref, ISIGoogle Scholar
    • Ghez A. M., Neugebauer G.& Matthews K.. 1993The multiplicity of T Tauri stars in the star forming regions Taurus–Auriga and Ophiuchus–Scorpius:a 2.2 μm speckle imaging survey. Astron. J. 106, 2005-2023(doi:10.1086/116782). Crossref, ISIGoogle Scholar
    • Ghez A. M., McCarthy D. W., Patience J. L.& Beck T. L.. 1997The multiplicity of pre-main-sequence stars in southern star-forming regions. Astrophys. J. 481, 378-385. Crossref, ISIGoogle Scholar
    • Goodman J.& Hut P.. 1993Binary-single-star scattering. V. Steady state binary distribution in a homogeneous static background of single stars. Astrophys. J. 403, 271-277(doi:10.1086/172200). Crossref, ISIGoogle Scholar
    • Goodwin S. P.& Kouwenhoven M. B. N.. 2009What does a universal initial mass function imply about star formation?Mon. Not. R. Astron. Soc. 397, L36-L40. Crossref, ISIGoogle Scholar
    • Goodwin S. P.& Kroupa P.. 2005Limits on the primordial stellar multiplicity. Astron. Astrophys. 439, 565-569. Crossref, ISIGoogle Scholar
    • Goodwin S. P.& Whitworth A. P.. 2007Brown dwarf formation by binary disruption. Astron. Astrophys. 466, 943-948. Crossref, ISIGoogle Scholar
    • Goodwin S. P., Whitworth A. P.& Ward-Thompson D.. 2004Simulating star formation in molecular cloud cores. I. The influence of low levels of turbulence on fragmentation and multiplicity. Astron. Astrophys. 414, 633-650. Crossref, ISIGoogle Scholar
    • Goodwin S. P., Kroupa P., Goodman A.& Burkert A.. 2007The fragmentation of cores and the initial binary population. Protostars and planets V(eds , Reipurth B., Jewitt D.& Keil K.)133-147Tuscon, AZUniversity of Arizona Press. Google Scholar
    • Goodwin S. P., Nutter D., Kroupa P., Ward-Thompson D.& Whitworth A. P.. 2008The relationship between the prestellar core mass function and the stellar initial mass function. Astron. Astrophys. 477, 823-827. Crossref, ISIGoogle Scholar
    • Haisch K. E., Greene T. P., Barsony M.& Stahler S. W.. 2004A near-infrared multiplicity survey of class I/flat-spectrum systems in six nearby molecular clouds. Astrophys. J. 127, 1747-1754. Google Scholar
    • Heggie D. C.. 1975Binary evolution in stellar dynamics. Mon. Not. R. Astron. Soc. 173, 729-787. Crossref, ISIGoogle Scholar
    • Hills J. G.. 1975Encounters between binary and single stars and their effect on the dynamical evolution of stellar systems. Astron. J. 80, 809-825. Crossref, ISIGoogle Scholar
    • Hut P., McMillan S., Goodman J., Mateo M., Phinney E. S., Pryor C., Richer H. B., Verbunt F.& Weinberg M.. 1992Binaries in globular clusters. Publ. Astron. Soc. Pac. 104, 981-1034. Crossref, ISIGoogle Scholar
    • Klessen R. S., Krumholz M. R.& Heitsch F.. 2009Numerical star-formation studies:a status report. Adv. Sci. Lett.(http:arxiv.org/abs/0906.4452). Google Scholar
    • Köhler R., Kunkel M., Leinert C.& Zinnecker H.. 2000Multiplicity of X-ray selected T Tauri stars in the Scorpius–Centaurus OB association. Astron. Astrophys. 356, 541-558. ISIGoogle Scholar
    • Köhler R., Petr-Gotzens M. G., McCaughrean M. J., Bouvier J., Duchêne G., Quirrenbach A.& Zinnecker H.. 2006Binary stars in the Orion Nebula cluster. Astron. Astrophys. 458, 461-476. Crossref, ISIGoogle Scholar
    • Köhler R., Neuhäuser R., Krämer S., Leinert C., Ott T.& Eckart A.. 2008Multiplicity of young stars in and around R Coronae Australis. Astron. Astrophys. 488, 997-1006. Crossref, ISIGoogle Scholar
    • Konopacky Q. M., Ghez A. M., Rice E. L.& Duchêne G.. 2007New very low mass binaries in the Taurus \hboxstar-forming region. Astrophys. J. 663, 394-399. Crossref, ISIGoogle Scholar
    • Koresko C. D.. 2002Imaging the circumstellar environments of young binaries in southern star-forming regions. Astron. J. 124, 1082-1088. Crossref, ISIGoogle Scholar
    • Kouwenhoven M. B. N., Brown A. G. A., Portegies Zwart S. F.& Kaper L.. 2007The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2. Astron. Astrophys. 474, 77-104. Crossref, ISIGoogle Scholar
    • Kouwenhoven M. B. N., Goodwin S. P., Parker R. J., Davies M. B., Malmberg D.& Kroupa P.SubmittedThe formation of very wide binaries during the star cluster dissolution phase. Google Scholar
    • Kraus A. L.& Hillenbrand L. A.. 2007The role of mass and environment in multiple-star formation:a 2MASS survey of wide multiplicity in three young associations. Astrophys. J. 662, 413-430. Crossref, ISIGoogle Scholar
    • Kroupa P.. 1995aInverse dynamical population synthesis and star formation. Mon. Not. R. Astron. Soc. 277, 1491-1506. Crossref, ISIGoogle Scholar
    • Kroupa P.. 1995bThe dynamical properties of stellar systems in the Galactic disc. Mon. Not. R. Astron. Soc. 277, 1507-1521. Crossref, ISIGoogle Scholar
    • Kroupa P.& Bouvier J.. 2003The dynamical evolution of Taurus–Auriga-type aggregates. Mon. Not. R. Astron. Soc. 346, 343-353(doi:10.1046/j.1365-2966.2003.06645.x). Crossref, ISIGoogle Scholar
    • Kroupa P., Aarseth S.& Hurley J.. 2001The formation of a bound star cluster:from the Orion Nebula cluster to the Pleiades. Mon. Not. R. Astron. Soc. 321, 699-712. Crossref, ISIGoogle Scholar
    • Lada C. J.. 2006Stellar multiplicity and the initial mass function:most stars are single. Astrophys. J. 640, L63-L66. Crossref, ISIGoogle Scholar
    • Lada C. J.. 2010The physics and modes of star cluster formation:observations. Phil. Trans. R. Soc. A 368, 713-731(doi:10.1098/rsta.2009.0264). Link, ISIGoogle Scholar
    • Lada C. J.& Lada E. A.. 2003Embedded clusters in molecular clouds. Annu. Rev. Astron. Astrophys. 41, 57-115(doi:10.1146/annurev.astro.41.011802.094844). Crossref, ISIGoogle Scholar
    • Lafrenière D., Jayawardhana R., Brandeker A., Ahmic M.& van Kerkwijk M. H.. 2008A multiplicity census of young stars in Chamaeleon I. Astrophys. J. 683, 844-861. Crossref, ISIGoogle Scholar
    • Larson R. B.. 1972The collapse of a rotating cloud. Mon. Not. R. Astron. Soc. 156, 437-458. Crossref, ISIGoogle Scholar
    • Larson R. B.. 2002The role of tidal interactions in star formation. Mon. Not. R. Astron. Soc. 332, 155-164(doi:10.1046/j.1365-8711.2002.05281.x). Crossref, ISIGoogle Scholar
    • Law N. M., Hodgkin S. T.& Mackay C. D.. 2007Discovery of five very low mass close binaries, resolved in the visible with lucky imaging. Mon. Not. R. Astron. Soc. 368, 1917-1924. Crossref, ISIGoogle Scholar
    • Leinert C., Zinnecker H., Weitzel N., Christou J., Ridgway S. T., Jameson R., Haas M.& Lenzen R.. 1993A systematic approach for young binaries in Taurus. Astron. Astrophys. 278, 129-149. ISIGoogle Scholar
    • Mathieu R. D.. 1994Pre-main-sequence binary stars. Annu. Rev. Astron. Astrophys. 32, 465-530(doi:10.1146/annurev.aa.32.090194.002341). Crossref, ISIGoogle Scholar
    • Maxted P. F. L., Jeffries R. D., Oliveira J. M., Naylor T.& Jackson R. J.. 2008A survey for low-mass spectroscopic binary stars in the young clusters around σ Orionis and λ Orionis. Mon. Not. R. Astron. Soc. 385, 2210-2224(doi:10.1111/j.1365-2966.2008.13008.x). Crossref, ISIGoogle Scholar
    • Mazeh T., Goldberg D., Duquennoy A.& Mayor M.. 1992On the mass-ratio distribution of spectroscopic binaries with solar-type primaries. Astrophys. J. 401, 265-268(doi:10.1086/172058). Crossref, ISIGoogle Scholar
    • Moraux E., Lawson W. A.& Clarke C. J.. 2007η Chamaeleontis:abnormal initial mass function or dynamical evolution?Astron. Astrophys. 473, 163-170(doi:10.1051/0004-6361:20066847). Crossref, ISIGoogle Scholar
    • Parker R. J., Goodwin S. P., Kroupa P.& Kouwenhoven M. B. N.. 2009Do binaries in clusters form in the same way as in the field?Mon. Not. R. Astron. Soc. 397, 1577-1586(doi:10.1111/j.1365-2966.2009.15032.x). Crossref, ISIGoogle Scholar
    • Patience J., Ghez A. M., Reid I. N.& Matthews K.. 2002A high angular resolution multiplicity survey of the open clusters α Persei and Praesepe. Astron. J. 123, 1570-1602(doi:10.1086/338431). Crossref, ISIGoogle Scholar
    • Petr M. G., Coude Du Foresto V., Beckwith S. V. W., Richichi A.& McCaughrean M. J.. 1998Binary stars in the Orion Trapezium cluster core. Astrophys. J. 500, 825-837(doi:10.1086/305751). Crossref, ISIGoogle Scholar
    • Preibisch T., Brown A. G. A., Bridges T., Guenther E.& Zinnecker H.. 2002Exploring the full stellar population of the Upper Scorpius OB association. Astron. J. 124, 404-416(doi:10.1086/341174). Crossref, ISIGoogle Scholar
    • Reid I. N.& Gizis J. E.. 1997Low-mass binaries and the stellar luminosity function. Astron. J. 113, 2246-2269(doi:10.1086/118436). Crossref, ISIGoogle Scholar
    • Reipurth B.& Clarke C. J.. 2001The formation of brown dwarfs as ejected stellar embryos. Astron. J. 122, 432-439(doi:10.1086/321121). Crossref, ISIGoogle Scholar
    • Reipurth B.& Zinnecker H.. 1993Visual binaries among pre-main sequence stars. Astron. Astrophys. 278, 81-108. ISIGoogle Scholar
    • Reipurth B., Guimarães M. M., Connelley M. S.& Bally J.. 2007Visual binaries in the Orion Nebula cluster. Astron. J. 134, 2272-2285(doi:10.1086/523596). Crossref, ISIGoogle Scholar
    • Scally A., Clarke C. J.& McCaughrean M. J.. 1999Wide binaries in the Orion Nebula cluster. Mon. Not. R. Astron. Soc. 306, 253-256(doi:10.1046/j.1365-8711.1999.02513.x). Crossref, ISIGoogle Scholar
    • Scally A., Clarke C. J.& McCaughrean M. J.. 2005Dynamical evolution of the Orion Nebula cluster. Mon. Not. R. Astron. Soc. 358, 742-754(doi:10.1111/j.1365-2966.2004.08617.x). Crossref, ISIGoogle Scholar
    • Shatsky N.& Tokovinin A. A.. 2002The mass ratio distribution of B-type visual binaries in the Sco OB2 association. Astron. Astrophys. 382, 92-103(doi:10.1051/0004-6361:20011542). Crossref, ISIGoogle Scholar
    • Tokovinin A. A.& Smekhov M. G.. 2002Statistics of spectroscopic sub-systems in visual multiple stars. Astron. Astrophys. 382, 118-123(doi:10.1051/0004-6361:20011586). Crossref, ISIGoogle Scholar
    • Vesperini E.. 2010Star cluster dynamics. Phil. Trans. R. Soc. A 368, 829-849(doi:10.1098/rsta.2009.0260). Link, ISIGoogle Scholar
    • Whitworth A. P.& Stamatellos D.. 2006The minimum mass for star formation and the origin of binary brown dwarfs. Astron. Astrophys. 458, 817-829(doi:10.1051/0004-6361:20065806). Crossref, ISIGoogle Scholar