Binary Stars by R8RVowI9

VIEWS: 26 PAGES: 35

									Addressing confusion in double
      star nomenclature:

The Washington Multiplicity Catalog

   William I. Hartkopf & Brian D. Mason
          U.S. Naval Observatory

                            U.S. Naval Observatory
                 A Welcome “Problem”

• New observing and reduction techniques 
   – New classes of companions (e.g., brown dwarfs,
     exoplanets)
   – Previously distinct classes (e.g., “visual” and “SB”)
     now observable by multiple techniques
   – Future interferometers, astrometric satellites, etc means
     the problem will become worse!
• Result is greater understanding for the scientist,
  but greater challenges for the cataloger!

                                        U.S. Naval Observatory
              So What IS the Problem?

• Different techniques mean different nomenclature!
   – Visual binaries: “discoverer designations”
     (e.g., S or STF 1413, b or BU 96)
   – Spectroscopic binaries: HD, etc.
   – Eclipsing binaries: variable star designation
   – Occultation binaries: SAO, ZC
• Multiple method may yield multiple designations
• Component confusion! One person’s AB pair may be
  another’s ab or BA or primary/secondary!


                                    U.S. Naval Observatory
               Addressing the Problem

• Informal working group (1999) came up with four
  suggested schemes:
   – KoMa (D. Kovaleva & O. Malkov): Alphabetic,
     numeric and Roman numerals to indicate hierarchy and
     companion type
   – UC ( S. Urban & T. Corbin): numeric scheme similar
     to library call numbers
   – Sequential (L. Dickel & P. Dubois): components
     assigned numbers in order of discovery
   – WMC (Washington Multiplicity Catalog): based on
     upper/lower case letters of WDS, with extensions

                                     U.S. Naval Observatory
                    Addressing the Problem, II

• IAU Symposium 200: WMC favored. Sequential scheme
  deemed sufficiently different from others for further
  discussion.
• IAU-GA XXIV: methods for clearing up nomenclature
  ambiguities discussed. WMC endorsed and Class C
  resolution ratified by Commissions 5 (Documentation &
  Astronomical Data), 8+24 (Astrometry), 26 (Double &
  Multiple Stars), 42 (Close Binary Stars), and 45 (Stellar
  Classification):



                                       U.S. Naval Observatory
           On Designating Components of Binary/Multiple Star Systems


Recognizing
• the increasing synergy of techniques for the investigation of stellar
   companions blurring the traditional distinction between
   astrometric,spectroscopic, and photometric binary and multiple stars;
• the detection of substellar (including planets) as well as stellar components by
   these techniques and,
• the need for a simple, unambiguous, flexible, and computer friendly
   designation scheme for components of binary and multiple star systems,
• Noting that future ground and space-based telescope projects have the
   potential to detect both substellar as well as stellar components in increasingly
   large numbers,
Recommends that
• a uniform designation scheme, based on expansion of the new WDS system,
   be developed during the next 3 years to include all types of components and
   that this be reviewed in time for its adoption to be considered at General
   Assembly XXV.

                                                       U.S. Naval Observatory
                      Implementation

• Present sample of resulting scheme at Colloquium 191.
• MODIFY!
• Present modified scheme to SOC of IAU-GA XXV
  Special Session 3: A New Classification Scheme for
  Double Stars.
• MODIFY AGAIN!
• Present further modified scheme at SPS3, July 18, 2003.
• If approved, present all-sky WMC at 2006 GA.
• Continue updates to WMC.


                                      U.S. Naval Observatory
                    Roots of the WMC

•    WDS: principal database of visual double and multiple
     star data for the astronomical community
    – Maintained at USNO, updated nightly
    – 597,579 measures for 99,284 pairs (as of Feb 2003)
•    Delta-m catalog: differential magnitudes not in WDS
•    Orbit Catalog: 1,692 systems
•    Interferometric Catalog: 138,532 high-res observations
     for 53,063 stars



                                      U.S. Naval Observatory
         Applying WDS rules to the WMC

•    WDS lists all resolved systems. Many components are
     detected but not resolved, however:
    1. spectroscopic doubles (SB1 and SB2),
    2. photometric or eclipsing binaries,
    3. astrometric doubles,
    4. lunar occultation doubles,
    5. other doubles,
    6. planets, other substellar objects
•    WDS nomenclature rules (with slight modification) can
     accommodate all types of double stars.


                                       U.S. Naval Observatory
                 WDS and Hierarchy

• WDS is system-based rather than object-based.
   – For object-based scheme, N objects  N entries
   – For system-based WDS, N objects  up to N(N-1)/2
     entries
• WDS also contains measures between photocenters.
• Multiple systems may become quite complex as N
  increases. However, WDS lists only pairings actually
  measured. Observers’ common sense usually implies
  system hierarchy.
• WDS also includes measures of optical pairs.

                                    U.S. Naval Observatory
                Determination of Hierarchies

• Hierarchy based on orbital period and/or separation. The
  3:1 ratio of semi-major axes (R.S. Harrington) generally
  followed. Exceptions:
   – Separations >1” usually given upper-case letters.
   – 3:1 ratio assumes physicality. However, most visual
      doubles do not have enough measures to determine
      whether motion is Keplerian or rectilinear. Assume all
      double stars within some small separation are of
      interest.



                                        U.S. Naval Observatory
          Rules of Component Designation

• WDS nomenclature handles second level hierarchies.
• WMC will cover more complex systems:
• Level 1  capital letters
   – STF1523 AB
• Level 2  lower case letters
   – FIN 347 Aa,Ab
• Level 3  numbers
   – ORD 666 Ba1,Ba2
• Higher levels  alternate lower case letters and numbers


                                      U.S. Naval Observatory
               Component Designation, II

•   Delimiter: comma, with full component identifier before
    and after (e.g., Aa,Ab). Exceptions:
    –  Assume “A,B” if no designation
      (e.g., A 1248 = A 1248 A,B).
    – Delimiter assumed if only two characters
      (e.g., WAK 8 CD = WAK 8 C,D).
•   WMC will strive to maintain hierarchies, but this is not
    always possible, given often very limited knowledge.
    We’ll do the best we can!
•   If a subsystem cannot be assigned unequivocally, a
    tentative “best guess” assignment will be given and a
    note added to the catalog.

                                            U.S. Naval Observatory
Illustrating a Complex System




                 U.S. Naval Observatory
                    The Sample WMC

• RA = 11h – 11h30m band. Historically compelling (“home”
  of x UMa), and has a variety of component types:
   – astrometric binaries,
   – X-ray binaries, cataclysmic variables, related objects,
   – eclipsing binaries,
   – occultation binaries,
   – spectroscopic (SB1 + SB2) and spectrum binaries,
   – interferometric binaries,
   – visual binaries, and
   – planetary companions (by extending to 10h59m.5 …)


                                       U.S. Naval Observatory
                       Sources of Multiplicity

•   WDS and other USNO double star catalogs
•   Downes et al. 2001, “A Catalog and Atlas of Cataclysmic Variables: On-line
    Version”, PASP 113, 764 (http://icarus.stsci.edu/~downes/cvcat/)
•   Ritter & Kolb 1998, “Catalogue of cataclysmic binaries, low-mass X-ray
    binaries , and related objects (Sixth edition)”, A&AS 129, 83
•   Batten et al, 1989, “Eighth Catalog of the Orbital Elements of Spectroscopic
    Binary Systems”, Pub. DAO, v. 17
•   Pourbaix et al., 2003, “Ninth Catalogue of Spectroscopic Binary Orbits”
    (http://sb9.astro.ulb.ac.be/)
•   Svechnikov & Bessonova 1984, “Catalog of Orbital elements, Masses and
    Luminosities of close double stars”, Bull. Inf. CDS 26, 99
•   van Paradijs 1995, “A Catalogue of X-Ray Binaries”, in ‘X-ray Binaries’,
    Lewin et al, eds., Cambridge Univ. Press, ch. 14, p 536-577
•   California & Carnegie Planet Search website (http://exoplanets.org) and links
•   Other sources needed!

                                                     U.S. Naval Observatory
             Contributions by Technique

• Techniques contribute to the sample WMC as follows:
   – 95.8% = visual binaries and optical pairs,
   – 50.6% = interferometric binaries and optical pairs,
   – 1.7% = spectroscopic binaries,
   – 1.4% = cataclysmic variables or related objects,
   – 1.0% = occultation binaries,
   – 0.3% = astrometric binaries,
   – 0.2% each eclipsing binaries and X-ray binaries,
   – 0.1% each spectrum binaries and planets.
• Techniques are complementary, so sum is >100%.

                                       U.S. Naval Observatory
                 Coordinate Matching

• System matches are based on stars’ arcsecond precise
  coordinates. The most time-consuming aspect of the WMC
  construction (by far!) was the improvement of the WDS’
  arcminute coordinates:
   – 80% matched to Hipparcos or Tycho-2.
   – additional 19% matched to GSC2, USNO A2, 2MASS,
     etc. via individual inspection using ALADIN.
   – 1.3% (21 pairs) still have only arcminute accuracy
     coordinates. Nearly all are older, unconfirmed, visual
     doubles (very wide cpm pairs or suspect coordinates).


                                      U.S. Naval Observatory
                    Sample Statistics

• The 1,465 systems in this slice of the sky may be broken
  down as follows:
   – 1,336 (91%) simple binaries
   – 80 (5.5%) non-hierarchical triples
   – 16 (1.1%) non-hierarchical systems, >3 components
   – 25 (1.7%) hierarchical triples
   –     8 (0.5%) hierarchical systems, >3 components




                                     U.S. Naval Observatory
               Explanation of the Columns

1     = WMC designation (WDS or J2000 arcminute coordinates)
2     = component designation (AB; Aa,Ab; etc.)
3     = name (HD, DM, variable star desig., discoverer desig., etc.)
4     = name (Tycho-2, GSC2, USNO A2, 2MASS, etc.)
5     = angular separation (vector sep, predicted from SB, etc.)
6     = orbital period
7, 8 = magnitudes (filter codes if not V, flags for variability)
9,10 = spectral types
11 = parallax (from Hipparcos, orbital parallax, etc)
12,13 = masses (or mass function, mass ratio. etc.)
14 = binary type (visual, spectroscopic, etc.)
15 = references (with web links)
16 = J2000 arcsecond coordinates
                                                U.S. Naval Observatory
           WMC Page 1

•   Text




                  U.S. Naval Observatory
           WMC Page 2

•   Text




                  U.S. Naval Observatory
           Int 4 Page

•   Text




                  U.S. Naval Observatory
           Orb Page 1

•   Text




                  U.S. Naval Observatory
           Orb Page 2

•   Text




                  U.S. Naval Observatory
           SB9 Page

•   Text




                 U.S. Naval Observatory
           CCV Page

•   Text




                 U.S. Naval Observatory
           CCP Page

•   Text




                 U.S. Naval Observatory
                          Sample WMC Examples


   WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11131-4217 AB         CD -41 6409        2.503     .       10.55   11.69   .          .
11131-4217 AC         CD -41 6409        5.46      .       10.55   13.6    .          .

10595+4026 AB        *   47 UMa         0.14     2.982y   5.05            G0V       planet
10595+4026 AC        *   47 UMa         0.26     7.1 y    5.05            G0V       planet




                                                                 U.S. Naval Observatory
                          Sample WMC Examples


WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11018+2952 Aa,Ab      HD 95515           0.262     .        7.8      .     K0         .
11018+2952 Aa,B       HD 95515           1.13      .        7.00    9.36   K0         .




                                                                U.S. Naval Observatory
                          Sample WMC Examples


WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11080-7742 Aa,Ab      ** GHE 35          0.72      .        7.03k   8.38k ?e          .
11080-7742 AB         ** GHE 35          2.7       .        7.03k   9.5 k ?e          .
11080-7742 Ab1,Ab2    ** BNK   1         0.100     .        8.92k   9.32k .           .
11080-7742 AC         ** SZR   1        17.        .        7.03k   10.1 k   ?e       .




                                                                U.S. Naval Observatory
                          Sample WMC Examples


WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11291+3920 AB         HD 99787           5.45      .        5.35   10.67   A2V        .
11291+3920 AC         HD 99787         216.55      .        5.35   11.6    A2V        .
11291+3920 AD         HD 99787         344.36      .        5.35    7.73   A2V        K0
11291+3920 AE         HD 99787         100.33      .        5.35   10.6    A2V        .
11291+3920 AF         HD 99787         131.03      .        5.35   10.3    A2V        .
11291+3920 AG         HD 99787         330.27      .        5.35   10.3    A2V        .




                                                                U.S. Naval Observatory
                          Sample WMC Examples


WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11182+3132 Aa,Ab      * xi UMa           0.053 669.18 d     4.41     .     G0V        M3V?
11182+3132 AB         HD 98231           2.536   59.878y    4.41    4.87   G0V        F8.5V
11182+3132 AC         HD 98231          54.31      .        4.41   15.0    G0V        .
11182+3132 Ba,Bb      * xi UMa           0.33 m   3.981d    4.87     .     F8.5V      planet?
11182+3132 Ba,Bc      HD 98230           0.026     .        4.87     .     F8.5V      K2-3V?




                                                                U.S. Naval Observatory
                          Sample WMC Examples


WMC....... Comp..... ?? NAME........ Sep....* Period.y     Mag1.f Mag2.f Spec1..... Spec2...
----------------------------------------------------------------------------------------------
11151-6116 Aa,Ab      HD 97950           0.339     .       10.5    11.1    .          .
11151-6116 Aa,Ac      HD 97950           0.371     .       10.5    11.3    .          .
11151-6116 Aa,Ad      HD 97950           0.784     .       10.5    10.3    WN...      WN...
11151-6116 AB         HD 97950           1.81      .        9.03   10.8    WN...      WN...
11151-6116 AC         HD 97950           2.69      .        9.03   11.3    WN...      .
11151-6116 AD         HD 97950           3.54      .        9.03   12.3    WN...      .
11151-6116 AE         HD 97950           4.59      .        9.03   11.8    WN...      .




                                                                U.S. Naval Observatory
                                 Help!

• Your suggestions needed (format, information to add or
  delete, etc.). See WMC website (link from WDS website:
  http://ad.usno.navy.mil/wds/wds.html)
   – is arcminute-accuracy WMC designation sufficient?
   – should planet designations be different?


• Your data are needed (for WDS, Orb6, SB9, etc as well!)
  send comments, etc. to wih@usno.navy.mil or
  bdm@draco.usno.navy.mil



                                           U.S. Naval Observatory

								
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