Archive for March, 2017

The (paper-)story of GG Car

Posted March 12, 2017 By grigoris

As I was diving into the literature of GG Car (aka HD 94878 or CPD-59 2855 or MWC 215 or … for more see Simbad!) I got overwhelmed of the number of papers and how back it goes. I only wanted to make a summary (for a forthcoming paper) but since I spent so much time and effort to read through the literature I though to make some kind of a timeline with some notes.

  • 1896 / (yea … since then!) Pickering, E. C. 1896 (Astron. Nachr., 141, 169), Pickering, E. C. & Fleming, W. P. 1896 (ApJ, 4, 142)
    First reference of GG Car as a star with a peculiar spectrum and one that resembles η Car.
  • 1916 / Cannon, A. J. & Pickering, E. C. 1916 (An. Har., 76, 19)
    GG Car is found under P Cygni type stars. All these stars are characterized by strong Balmer lines and look similar to β Lyr.
  • 1930 / Kruytbosch, W. E. 1930 (BAN, 6, 11)
    Identifying a period of 31.043 d using the minima of the light curve, from photographic plates. A binary system with two variable stars is proposed.
  • 1933 / Greenstein, N. K. 1938 (BHarO, 908, 25)
    The main conclusion from this work is a re-determination of the period to 62.07 d, based on the argument that two following minima were not the same.
  • 1950 / Thackeray, A. D. 1950 (MNRAS, 110, 524)
    In a search for southern stars related with nebulosity, nothing is found for GG Car.
  • 1955 / Smith, H. J. 1955 (PhD thesis, Harvard University)
    A slit spectrum revealed H and FeII lines, without any absorption lines or P Cygni profiles detected.
    [Note: I couldn’t check this reference myself and the text is borrowed from Herbig 1960, and others who also cite this thesis later on.]
  • 1960 / Herbig, G. H. 1960 (ApJS, 4, 337)
    Mentioned on the catalog, but only refers to the works by Smith 1955 and Thackeray 1950.
  • 1973 / Allen, D. A. 1973 (MNRAS, 161, 145)
    GG Car is found to exhibit an infrared excess (JHK measurements).
  • 1974 / Swings, J. P. 1974 (A&A, 34, 333); Albers, H. 1974 (ApJ,189,463)
    Swings: Spectroscopic observations (from ESO, La Silla, Chile) revealed [FeII] and [OI] emission lines, P Cygni profiles in the Balmer lines, and double-peaked profiles in FeII, which suggest a “thin equatorial ring rotating around the object”. Albers: GG Car displays two of the CaII triplet lines and a strong OI λ8446 line in emission (see Table 3).
  • 1976 / Allen, D. A. & Swings, J. P. 1976 (A&A, 47, 293), Henize 1976 (ApJS, 30, 491)
    Included in both of these catalogs: in Group 2 of Allen & Swings’ work as a peculiar Be star with infrared excess, and as an emission-line star in Henize’s work.
  • 1977 / Klare, G. & Neckel, T. (A&AS, 27, 215)
    UBVΗβ and polarization measurements for a catalog of southern OB stars, including GG Car.
  • 1979 / Carlson, E. D. & Henize, K. G. 1979 (VA, 23, 213)
    Included in the catalog of southern peculiar emission-line stars. [Note: I couldn’t access the paper though!]
  • 1980 / Cohen, M. & Barlow, M. J. 1980 (ApJ, 238, 585)
    Mid-infrared survey which identified GG Car with excess.
  • 1981 / Hernandez, C. A.; Sahade, J.; Lopez, L.; Thackeray, A. D. 1981 (PASP, 93, 747)
    There is a great introduction (that perhaps inspired this post also!). They describe the observables of GG Car and they give a period of 31.03 d, derived from spectroscopic observations.
  • 1982 / Bouchet, P. & Swings, J. P. 1982 (IAUS, 98, 241); Barbier, R.; Swings, J. P. 1982 (IAUS, 98, 103)
    Bouchet: Near infrared (JHK) observations and variability search. Barbier: Polarization measurements (in UBV).
  • 1984 / Gosset, E.; Surdej, J.; Swings, J. P. 1984 (A&AS, 55, 411)
    Optical photometry (UBV) and period determination (two periods at 31.020 and 62.039 d found).
  • 1985 / Gosset, E.; Hutsemekers, D.; Swings, J. P.; Surdej, J. 1985 (A&A, 153, 71)
    Great introduction. Minor summary of spectral properties. Binary solution from radial velocity measurements.
  • 1987 / Brandi, E. & Gosset, E. 1987 (A&AS, 68, 283)
    The ultraviolet spectrum and light curve for GG Car, which was found similar to the optical light curve.
  • 1988 / McGregor, P. J.; Hyland, A. R.; Hillier, D. J. 1988 (ApJ, 324, 1071)
    Infrared spectra of GG Car, exhibiting H, He, Fe lines along with CO bandhead in emission. Detailed measurements of the various features, and extraction of physical parameters for all systems (very good paper).
  • 1992 / Lopes, D. F.; Damineli Neto, A.; de Freitas Pacheco, J. A. 1992 (A&A, 261, 482), Gnedin, Yu. N.; Kiselev, N. N.; Pogodin, M. A.; Rosenbush, A. E.; Rosenbush, V. K. 1992 (SvAL, 18, 182)
    Lopes: Optical and infrared spectra. The presence of HeI in emission suggested a B0-B2 spectral classification. Various physical parameters are given: EQW(NaI)=1.18 Å, E(B-V)=1.1 mag, distance=2.5 kpc, Mv=-6.3 mag, Mb=-8.2 mag, M=25 M, mass-loss rate=5.7 M/year, V=670 km/s (good paper on physics also). Gnedin: Polarimetric observations on southern classical and peculiar Be stars.
  • 1996 / Morris, P. W.; Eenens, P. R. J.; Hanson, M. M.; Conti, P. S.; Blum, R. D. 1996 (ApJ, 470, 597)
    Infrared spectroscopy showing: HeI, FeII, MgII, HI, CO features, and first indication of variability (in infrared).
  • 2004 / Machado, M. A.; de Araújo, F. X.; de Faria Lopes, D.; Pereira, C. B. 2004 (RMxAC, 20, 239)
    Optical spectral variability of GG Car.
  • 2007 / Groh, J. H.; Damineli, A.; Jablonski, F. 2007 (A&A, 465, 993)
    Infrared spectra displaying FeII, MgII, CI, HeI 10830 Å, and Pa γ in emission.
  • 2009 / Pereyra, A.; de Araújo, F. X.; Magalhães, A. M.; Borges Fernandes, M.; Domiciano de Souza, A. 2009 (A&A, 508, 1337) Kraus, M 2009 (A&A, 494, 253)
    Pereyra: A good introduction with some more references on previous works on polarization. Spectropolarimetric data around Hα are presented for the first time for GG Car, helping constraining the geometry of the system. Kraus: The 13CO enrichment in B[e]SGs, which hints their evolved nature. References to other works that identify 13CO features in GG Car (with a 12CO/13CO less than 10).
  • 2010 / Borges Fernandes, M. 2010 (RMxAC, 38, 98)
    Interferometric observations of B[e]SGs including G Car. An inclination angle of 50°-60° at a distance of 1 kpc is stated.
  • 2012 / Marchiano, P.; Brandi, E.; Muratore, M. F.; Quiroga, C.; Ferrer, O. E.; García, L. G. 2012 (A&A, 540, 91)
    An introduction with many references about the binary nature of GG Car and variability in general. Identifying the orbital parameters for the binary (with spectroscopic data) and extracting physical parameters for the star and the environment: eccentricity = 0.28, period = 31.033 d, mass ratio = 2.2 with Mprimarysin3i=18 M and Msecondarysin3i=8 M, Teff = 23000 K, logg=3, E(B-V)=0.39 mag, inclination angle between 54°-72°. A gaseous and dusty envelope is assumed (see Table 4 for details physical properties). Even though the calculations were performed for a single star the a (of two similar-B-type stars) would still fit the observed properties, if the second contributes les than 10% of the primary flux. A distance of 5 kpc was estimated using two different methods.
  • 2013 / Kraus, M.; Oksala, M. E.; Nickeler, D. H.; Muratore, M. F.; Borges Fernandes, M.; Aret, A.; Cidale, L. S.; de Wit, W. J. 2013 (A&A, 549, 28)
    The most updated summary (introduction) for the star. Infrared high-resolution spectra revealed the structure of the dusty disk (through the detailed analysis of the CO profiles). A Tco = 3200 K leads to a detached and circumbinary disk. Its motion is consistent with a Keplerian rotation (at 80 km/s). A ratio of 12CO/13CO=15±5 confirms the evolved nature of GG Car. less than 10). Two scenarios for the disk formation are discussed, including the possibility of a non-conservative Roche lobe overflow or that the accumulation of material has been performed gradually through a classical Be phase. Although none can be excluded, the second case is only slightly favored, due to the extreme conditions needed for first scenario.
  • 2015 / Domiciano de Souza, A.; Borges Fernandes, M.; Carciofi, A. C.; Chesneau, O. 2015 (IAUS, 307, 291)
    Mid-infrared interferometric observations (MIDI/ESO-VLTI), showing an inclination angle of ~60° (consistent with Marchiano et al. 2012). The central star is modeled as a B-type star with Teff~20000 K, R~10 R, L~104 L, which can describe the observed data but not all lines (as they put it: “However, they are not a perfect representation of the circumstellar environment of GG Car”. They do find that the dust is formed in a compact ring much closer to the start than expected (≤100 R).

UPDATE 5/5/2017: Adding Albers 1974.
UPDATE 7/5/2017: Adding Barbier & Swings 1982.