Planets around A-type stars

By grigoris | Filed in Astronomy

For an unknown reason I found this footnote from Menu et al. 2015 (A&A, 581A, 107) very interesting:

It is interesting to note that several of the few directly imaged planetary companions are found around A-type stars, which are descendants of Herbig Ae/Be stars. Examples of A-type exoplanet host stars are HR 8799 (e.g., Marois et al. 2008), HD 95086 (e.g., Rameau et al. 2013), κ And (e.g., Carson et al. 2013), β Pic (e.g., Lagrange et al. 2010), and HD 100546 (e.g., Quanz et al. 2013).

The (paper-)story of HD 87643

By grigoris | Filed in Astronomy

A summary for HD 87643 (or MWC 198, Hen 3-365, V640 Car, … see also Simbad). That is a great number of papers (similar to the post for GG Car).

  • 1909 /
    Object of the Henry Draper catalog.
  • 1933 / Merrill, P. W.; Burwell, C. G. 1933 (ApJ, 78, 87)
    First reference as a Be star.
  • 1968 / Hiltner, W. A.; Stephenson, C. B.; Sanduleak, N. 1968 (ApL, 2, 153H)
    They identified Balmer lines with their absorption borders to be similar to those of P Cygni. They identified also FeII lines in emission. They argued that the star has changed significantly from a P Cygni star (in 1909) and as a emission line star with WR characteristics (referring to Münch Luis 1953; Boletin los Obs. de Ton. y Tae., No 8, 27) to a nova like object, similar to Nova Delphini 1967.
  • 1971 / Crampton, D. 1971 (AJ, 76, 260)
    Identifying it within an HII region (KCW 47).
  • 1972 / van den Bergh, S. 1972 (PASP, 84, 594)
    A nebula is identified. A suggestion of a B2 V star with Av=2.5 mad and Vo=6.0, at a distance of 500 pc is proposed.
  • 1973 / Allen, D. A. 1973 (MNRAS, 161, 145), Sanduleak, N.; Stephenson, C. B. 1973 (ApJ, 185, 899)
    Allen: H,K,L ir observations show excess which is accounted to “reradiation from circumstellar dust clouds” (the star belongs to Dn category, which means “D”ust and presence of “n”ebulosity). See also section 4 (explanation). Sanduleak: Identified as a peculiar Be star.
  • 1974 / Stephenson, C. B. 1974 (ApJ, 191, 685), Albers, H. 1974 (ApJ, 189, 463), Swings J. P. 1974 (A&A, 34, 333)
    Stephenson: A nova-like nature is proposed. There is “a diffuse absorption spectrum violet-displaced from the corresponding emission lines by many hundreds of km/s”. In Hiltner+ 1968 that was ~850 km/s while in the current work is ~900 km/s. Moreover, the P Cygni absorption, present in 1968, is gone in 1973 (current work). Other than that the spectrum is similar to Hiltner’s, but very different than the original observation in HD catalog (1909). Albers: Identification of the CaII triplet and the OI 8446 lines (with a strong presence). Swings: Similar spectrum to GG Car. Balmer lines with P Cygni profiles, FeII (double-peaked with ~30km/s) and [FeII] (diffuse) lines present.
  • 1976 / Williams, P. M.; Beattie, D. H.; Stewart, J. M. 1976 (Obs, 96, 184), Allen, D. A. 1976 (MNRAS, 174P, 29), Henize, K. G. 1976 (ApJS, 30, 491), Allen, D. A.; Swings, J. P. 1976 (A&A, 47, 293)
    Williams: First SED for HD 87643. Mid-r observations indicative of a dust shell presence. Allen: Deriving reddening parameters: Teff = 11000 K, Av=1.9 mag, B(B-V)/Av = 0.35. Henize: Catalog of emission line stars, object 365 (or MWC 198). Comments: “Hβ is seen in emission and a P Cygni profile is suspected at Hα. Classified as P Cyg in HDE and as W-R by Münch (1953). Mount Stromlo slit spectra show a peculiar nova-like spectrum (Henize 1962; Carlson 1968). A direct plate with the Mount Stromlo 74 inch (1.9 m) reflector shows the star to be centered in a peculiar nebula (Henize 1962). Recent observations of this star have been reported by Hiltner, Stephenson, and Sanduleak (1968) and by van den Bergh (1972).” Allen+Swings: Member of Group 2 of peculiar Be stars with IR excess (see paper for more).
  • 1979 / 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!]
  • 1981 / Surdej, A.; Surdej, J.; Swings, J. P.; Wamsteker, W. 1981 (A&A, 93, 285)
    The Reflection Nebula Surrounding HD87643: Imaging of HD 87643 shows a filamentary structured nebula (already mentioned in previous works) but more careful examination of Hα, [OIII], [SII] images showed that the nebula is not emitting, and the authors conclude towards a reflection nature of the nebula (at about 1 kpc). A spectrum of this nebula reveals strong P Cygni profiles (from Hβ to Hε) and many diffuse FeII lines. Expansion velocity ~1200 km/s
  • 1982 / Barbier, R.; Swings, J. P. 1982 (IAUS, 98, 103), de Freitas Pacheco, J. A.; Gilra, D. P.; Pottasch, S. R. 1982 (A&A, 108, 111)
    Barbier: Polarization measurements (in UBV). de Freitas Pacheco: Using UV spectra they estimated the mass loss ~7×107 M/year, evidence of a strong wind. See also the explanation of line formation (physics).
  • 1983 / Surdej, J.; Swings, J. P. 1983 (A&A, 117, 359)
    A non-isotropic and/or homogeneous environment is suggested based also in their previous work (Surdej+ 1981).
  • 1985 / de Freitas Pacheco, J. A.; Faria Lopes, D.; Landaberry, S. C.; Selvelli, P. L. 1985 (A&A, 152, 101)
    High-resolution UV spectra revealed a large number of lines. They discuss the excitation mechanism for FeII and provide a sketch of the circumstellar environment with: regions of ionized elements closer to the star, a region of neutral H, and a cold shell. The presence of a strong low ionization wind is mentioned. The wind velocity is estimated to ~800 km/s, with a mass loss of ~107 M/year, and the NaI doublet suggests a distance of 2 kpc.
  • 1986 / Olnon, F. M.; Raimond, E.; Neugebauer, G.; van Duinen, R. J.; Habing, H. J.; Aumann, H. H.; Beintema, D. A.; Boggess, N.; Borgman, J.; Clegg, P. E.; Gillett, F. C.; Hauser, M. G.; Houck, J. R.; Jennings, R. E.; de Jong, T.; Low, F. J.; Marsden, P. L.; Pottasch, S. R.; Soifer, B. T.; Walker, R. G.; Emerson, J. P.; Rowan-Robinson, M.; Wesselius, P. R.; Baud, B.; Beichman, C. A.; Gautier, T. N.; Harris, S.; Miley, G. K.; Young, E. 1986 (A&AS, 65, 607)
    Identified in the IRAS catalog.
  • 1987 / Volk, K.; Kwok, S. 1987 (ApJ, 315, 654)
    Identifying dust at 10 micron (~162 K).
  • 1988 / Shore, S. N.; Sanduleak, N.; Brown, D. N.; Sonneborn, G.; Bopp, B. W.; Robinson, C. R. 1988 (ESASP, 281a, 417), McGregor, P. J.; Hyland, A. R.; Hillier, D. J. 1988 (ApJ, 324, 1071)
    Shore: Similarities between Galactic and Magallanic Cloud stars, ie. HD 87643 (Hen3-365) to S22 in LMC. McGregor: IR spectra with HI lines present, but no first-overtone CO emission (in contrast to others lines GG Car, CPD-529243, CPD-572874). Estimating E(B-V)=1.0, 2.5 kpc, Teff~16000 K, L=4.9 L. Hot (T(K-L)=1190 K) and cold (T(25-60)=125 K) dust present for this star (they give other properties like radii and masses).
  • 1989 / Gaylard, M. J.; West, M. E.; Whitelock, P. A.; Cohen, R. J. 1989 (MNRAS, 236, 247)
    IR measurements and detection of OH.
  • 1990 / Deguchi, S.; Nakada, Y.; Sahai, R. 1990 (A&A, 230, 339), Shore, S. N.; Brown, D. N.; Bopp, B. W.; Robinson, C. R.; Sanduleak, N.; Feldman, P. D. 1990 (ApJS, 73, 461)
    Deguchi: No detection of CO or SiO in radio observations (HD 87643 is referred as SAO 237672). Shore: UV spectra for HD 87643, with P Cygni profiles. They assign a tentative B3 type with Teff~15000 K, L=3.7 L. Discussing the shell and how it affects the optical photometry. Identifying ~10% variation in the Fe II lines. Note from Section IIIb: “Van den Bergh (1972) attempted to determine the distance to He 3-365, assuming it to be a B2 V star. The derived distance of 0.5 kpc is certainly an underestimate. De Freitas Pacheco, Gilra, and Pottasch (1982) have analyzed the optical and UV pectrum of this star, concluding that it is a B supergiant at a distance of about 2-3 kpc. In a subsequent paper, de Freitas Pacheco, Gilra, and Pottasch (1985) refer to it as a B[e] star with a cool wind. They reported Mg II P Cygni profiles at high dispersion and suggested that the mass-loss rate is about M~lO-7 M/yr. Surdej and Swings (1983) detected a reflection nebula in the vicinity of the star. MHH88 report the detection of hot dust emission.”
  • 1992 / Gnedin, Yu. N.; Kiselev, N. N.; Pogodin, M. A.; Rosenbush, A. E.; Rosenbush, V. K. 1992 (SvAL, 18, 182), Lopes, D. F.; Damineli Neto, A.; de Freitas Pacheco, J. A. 1992 (A&A, 261, 482)
    Gndedin: A small polarization ~0.6% was observed, but without any variation reported. Lopes:Optical and ir spectroscopy, and short discussion of the the observed lines/features. Extracting physical properties: B3I, E(B-V)=1.3, d= 2.9 kpc, Mv=-7.6, Mbol=-8.9, M=34 M, Vwind=1300 km/s, MassLoss=1.2×10-5 M/year (a good physics paper also!).
  • 1994 / The, P. S.; de Winter, D.; Perez, M. R. 1994 (A&AS, 104, 315)
    Object refer to the catalog as “extreme emission line object”
  • 1998 / Lamers, H. J. G. L. M.; Zickgraf, F.-J.; de Winter, D.; Houziaux, L.; Zorec, J. 1998 (A&AS, 131, 401), Oudmaijer, R. D.; Proga, D.; Drew, J. E.; de Winter, D. 1998 (MNRAS, 300, 170)
    Lamers: It is not considered a definite SG since “show some characteristics of pre-main sequence stars (e.g. forbidden emission lines, evidence for disks, nebulosity) but there is no evidence for infall.” They provide a B4II[e] type classification for HD 87643. Noting: “HD 87643 is embedded in a reflecting nebula (Henize 1962, van den Bergh 1972, Surdej et al. 1981). The star was originally classified as a P Cygni type star and even a nova-like star (Carlson & Henize 1979). From IUE spectra McGregor et al. (1988a) and Shore et al. (1990) assigned an effective temperature of 15000 K to HD 87643. A distinctive peculiarity of HD 87643 is the presence of a strong, low ionization wind (de Freitas Pacheco et al. 1985, L ́opes et al. 1992). P Cygni line profiles are observed in many species, indicating outflows up to 1400 km s −1 (Surdej et al. 1981, Shore et al. 1990) and 1800 km s −1 (Oudmaijer et al. 1998). The estimated bolometric luminosity indicates that this star should be a bright giant (Zorec 1998; Oudmaijer et al. 1998).”. Yudin: Polarimteric observations show an increase of the polarization (compared to Barbier & Swings 1982 and Gnedin 1992) to ~1%, as well as some variability within a few days, consistent with HAeBe stars with Algol-like minima. Oudmaijer: A focused study on HD 87643, with high-resolution spectroscopy and medium-resolution spectropolarimetric data. Good intro. Imaging show nebulosity in V, R but not in Ha and [SII] (consistent with Surdej et al. 1981). Suggesting an evolved SG nature, with an “optically thick disk where irradiation pressure is sufficient to power mass loss from both the star and the disk”. Three different line-forming regions at ~1800 km/s (Ha and HeI), ~150km/s (H and FeII lines), and ~40km/s (forbidden lines, FeI, weaker FeII lines), with a disk-like structure. Commenting on the fainting magnitude of the system.
  • 1999 / Oudmaijer, R. D.; Drew, J. E. 1999 (MNRAS, 305, 166), Voors, R. H. M. 1999 (Ph.D. Thesis, Universiteit Utrecht, The Netherlands)
    Oudmaijer:Hα spectropolarimetry “indicates that the polarization profile can be best reproduced with a circumstellar disc that is both rotating and expanding”. Voors: Proposed a circumbinary disk.
  • 2000 / Valenti, J. A.; Johns-Krull, C. M.; Linsky, J. L. 2000 (ApJS, 129, 399), Clark, J. S.; Miroshnichenko, A. S.; Larionov, V. M.; Lyuty, V. M.; Hynes, R. I.; Pooley, G. G.; Coe, M. J.; McCollough, M.; Dieters, S.; Efimov, Yu. S.; Fabregat, J.; Goranskii, V. P.; Haswell, C. A.; Metlova, N. V.; Robinson, E. L.; Roche, P.; Shenavrin, V. I.; Welsh, W. F. 2000 (A&A, 356, 50)
    Valenti: Treated as Herbig Ae/Be star (id 89). A spectral type of B3.5 is given and a Av=1.88 mag. Clark: “HD 87643 (which faded by ∼1 mag since the 1960’s), and MWC 342 (∆V∼0.6 mag). Of these, only HD 87643 showed a long term trend in colour with brightness, becoming redder as it faded (Miroshnichenko 1998).” (Miroshnichenko A.S., 1998, In: Jaschek C., Hubert A.M. (eds.), B[e] stars, Kluwer Academic Publishers, p. 145)
  • 2001 / de Winter, D.; van den Ancker, M. E.; Maira, A.; Thé, P. S.; Djie, H. R. E. Tjin A.; Redondo, I.; Eiroa, C.; Molster, F. J. 2001 (A&A, 380, 609)
    Previously unpublished photometry from data “obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins (UBV(RI)c) and ESO and SAAO near-infrared (JHKLM) photometric systems”.
  • 2003 / Zickgraf, F.-J. 2003 (A&A, 408, 257)
    Detailed work on the spectral features observed on many galactic objects, including HD 87643 (simply put… must see paper!).
  • 2005 / Greaves, J. 2005 (IBVS, 5699, 18), Cool, Richard J.; Howell, Steve B.; Peña, Maria; Adamson, Andy J.; Thompson, Robert R. 2005 (PASP, 117, 462)
    Greaves: Assigning an SDOR type of variability for HD 87643 (V=8.68 – 9.83mag). Cool: They show UV spectra for HD 87643 as a comparison but they say they have been published previously (de Freitas Pacheco et al. 1982). The star is considered a similar source to the ones studied (iron stars) and the discussion about the nature is interesting. E.g. “hot Be star with an evolved late‐type secondary. The hydrogen emission features arise in the hot wind from the Be star, while the corresponding P‐Cygni absorption lines are produced from dense material in the expanding, radiation‐driven wind around each system.”
  • 2006 / Baines, D.; Oudmaijer, R. D.; Porter, J. M.; Pozzo, M. 2006 (MNRAS, 367, 737)
    They treat HD 87643 are a Herbig Ae/Be star (although its supergiant nature is not excluded, as it stands out from all others), plus they do not detect binarity. Hα emission is considered as an outflow, which consists of a high- and low-velocity components.
  • 2007 / Groh, J. H.; Damineli, A.; Jablonski, F. 2007 (A&A, 465, 993)
    Comment: “HD 87643 (Fig. 11) is thought to be an evolved B[e] star (Oudmaijer et al. 1998) and appears to be related to the LBV class, although the link is not clear yet. This object has an optical spectrum dominated by emission lines of Fe II and P Cygni profiles in the Balmer series, together with low excitation forbidden lines. The spectrum is produced by a fast polar wind combined with a slow disk wind (Oudmaijer et al. 1998). The ultraviolet and optical spectra of HD 87643 was previously discussed by de Freitas Pacheco et al. (1985,1982), who reported a strong spectral line variability. HD 87643 has a bright reflection nebula, which was analyzed by Surdej et al. (1981) and Surdej & Swings (1983). Its 2001 near infrared spectrum shows prominent Fe II, CI lines and Pa γ emission, compatible with the presence of a cold wind. He I 10 830 A presents a P-Cygni profile, with a weak emission and a strong absorption that goes up to -1750 km s-1, which is probably formed in the fast polar wind.”
  • 2007 / Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. 2007 (IBVS, 5863, 1)
    Included in the catalog of Variable stars (as V0640 Car).
  • 2009 / Millour, F.; Chesneau, O.; Borges Fernandes, M.; Meilland, A.; Mars, G.; Benoist, C.; Thiébaut, E.; Stee, P.; Hofmann, K.-H.; Baron, F.; Young, J.; Bendjoya, P.; Carciofi, A.; Domiciano de Souza, A.; Driebe, T.; Jankov, S.; Kervella, P.; Petrov, R. G.; Robbe-Dubois, S.; Vakili, F.; Waters, L. B. F. M.; Weigelt, G. 2009 (A&A, 507, 317), Kraus, M. 2009 (A&A, 494, 253)
    Millour: Just read this paper! 🙂 They identify a companion (much fainter). Their separation is ~51 AU, and the corresponding orbital period 20-50 years. The structure of the nebula may be the result of periastron passages. The suggested picture is: i. a giant/supergiant with a dusty disk (contributes mainly to the IR emission, which originates from the inner and hotter rim of the disk, 2.5-3 AU), ii. a much fainter companion star (probably not hot) embedded in a dusty envelope, iii. a cooler circumbinary envelope. Comment on the continuous fainting of the system.Kraus: Simple commenting on HD 87643 in Table A.1 with some physical parameters and further references.
  • 2011 / Carmona, A.; van der Plas, G.; van den Ancker, M. E.; Audard, M.; Waters, L. B. F. M.; Fedele, D.; Acke, B.; Pantin, E. 2011 (A&A, 533A, 39)
    They include HD 87643 as a Herbig Ae/Be object, although they mention its controversial nature. They do not detect any H2 (in IR spectra of R~90000 resolution CRIRES data)
  • 2015 / Menu, J.; van Boekel, R.; Henning, Th.; Leinert, Ch.; Waelkens, C.; Waters, L. B. F. M. 2015 (A&A, 581A, 107)
    They treat HD 87643 as a Herbig Be star. They find that T=Tsub( R/Rsub)^q with q=0.72 (for the temperature of the molecular disk at 10.7 um) and a half-light radius of 37.3 mas corresponding to 56 au. However, they do not detect any H2 (as found in other pre-main sequence objects) or report any gap presence, although a number of objects studied do show gaps.

And the list is not exhaustive.

A novel method to automatically detect and measure the ages of star clusters in nearby galaxies: Application to the Large Magellanic Cloud

T. Bitsakis, P. Bonfini, R. A. Gonzalez-Lopezlira, V. H. Ramirez-Siordia, G. Bruzual, S. Charlot, G. Maravelias, D. Zaritsky

We present our new, fully-automated method to detect and measure the ages of star clusters in nearby galaxies, where individual stars can be resolved. The method relies purely on statistical analysis of bservations and Monte-Carlo simulations to define stellar overdensities in the data. It decontaminates the cluster color-magnitude diagrams and, using a revised version of the Bayesian isochrone fitting code of Ramirez-Siordia et al., estimates the ages of the clusters. Comparisons of our estimates with those from other surveys show the superiority of our method to extract and measure the ages of star clusters, even in the most crowded fields. An application of our method is shown for the high-resolution, multi-band imaging of the Large Magellanic Cloud. We detect 4850 clusters in the 7 deg2 we surveyed, 3451 of which have not been reported before. Our findings suggest multiple epochs of star cluster formation, with the most probable occurring ~310 Myr ago. Several of these events are consistent with the epochs of the interactions among the Large and Small Magellanic Clouds, and the Galaxy, as predicted by N-body numerical simulations. Finally, the spatially resolved star cluster formation history may suggest an inside-out cluster formation scenario throughout the LMC, for the past 1 Gyr.

arXiv: 1707.02311

“Dude” by Peblo

By grigoris | Filed in Astronomy

peblo-Dude

by PEBLO

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The (paper-)story of Hen 3-298

By grigoris | Filed in Astronomy

Similarly to the post for GG Car, I though that it is better to keep a track of all papers I find for my sample. As far as Hen 3-298 (Simbad) the results are not that many!

  • 1966 / Wray, J. D. 1966(PhD thesis, Northwestern University)
    First detection as an Hα emission star.
  • 1976 / Henize, K. G. 1976 (ApJS, 30, 491)
    Also included in this catalog for Hα emission stars in the Southern Skies.
  • 1986 / Olnon, F. M.; Raimond, E.; Neugebauer, G.; van Duinen, R. J.; Habing, H. J.; Aumann, H. H.; Beintema, D. A.; Boggess, N.; Borgman, J.; Clegg, P. E.; Gillett, F. C.; Hauser, M. G.; Houck, J. R.; Jennings, R. E.; de Jong, T.; Low, F. J.; Marsden, P. L.; Pottasch, S. R.; Soifer, B. T.; Walker, R. G.; Emerson, J. P.; Rowan-Robinson, M.; Wesselius, P. R.; Baud, B.; Beichman, C. A.; Gautier, T. N.; Harris, S.; Miley, G. K.; Young, E. 1986 (A&A, 65, 607)
    Detected as an IR excess source.
  • 1994 / The, P. S.; de Winter, D.; Perez, M. R. 1994 (A&AS, 104, 315)
    Included in this catalog as an emission line star.
  • 2005 / Miroshnichenko, A. S.; Bjorkman, K. S.; Grosso, M.; Hinkle, K.; Levato, H.; Marang, F. 2005 (A&A, 436, 653)
    The first dedicated study of Hen 3-298. They identified double-peaked emission lines, such as Hα with a stronger red peak, and the [CaII] doublet. [OI] lines were found single-peaked. They also detected CO features in emission and estimated the temperature ~2000 K, suggesting that originates from a dust free zone, inside but close to the dusty disk. Moreover, they estimate log L/L∼ 5.1 and a spectral type of no earlier than B3, at a distance of 3-4.5 kpc. Suggesting a supergiant nature.
  • 2013 / Oksala, M. E.; Kraus, M.; Cidale, L. S.; Muratore, M. F.; Borges Fernandes, M. 2013 (A&A, 558A, 170)
    Part of the IR survey. Detecting and studying the CO features (also estimating ~2000 K), and estimating the ratio 12CO/13CO=20±5 (consistent with supergiants; Kraus 2009).

“Vegan” by PEBLO

By grigoris | Filed in Astronomy

peblo-Vegan

by PEBLO

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Finally … the Magellanic Clouds by eye!

By grigoris | Filed in Astronomy

During the last weekend I went hiking – albeit with a company of many astronomers! – a bit outside Santiago (we actually camp at Banos Colina in Cajon del Maipo). The mountain views were impressive, but during night I got another stunning view. As we were relaxing in the thermal pools we were starring the sky as the night came. And suddenly we spotted the Magellanic Clouds! Finally after so many years working with the Clouds I had the opportunity to gaze them visually. Simply amazing …

The following picture was taken mostly to verify their existence (and as … a memory!).

The Magellanic Clouds (Banos )

The Magellanic Clouds (Banos Colina, Cajon del Maipo, Santiago, Chile).

The (paper-)story of GG Car

By grigoris | Filed in Astronomy

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.

The Southern sky

By grigoris | Filed in Astronomy

When I first looked at the Southern sky from New Zealand I was … amazingly lost! There was actually not many stars I could really identify. Only Orion and Canis Majoris but … upside down!

Really lost under the sky of New Zealand.

Really lost under the sky of New Zealand.


I was a bit unlucky with the conditions in New Zealand, either cloudy nights or under light polluted places, so I didn’t have many opportunities to enjoy the Southern sky. Fortunately, I am in Valparaiso of Chile now, during summer with many clear nights, and I have just started to figure out where is what (like Carina). Still though, I miss the Magellanic Clouds…

At Valparaiso !

By grigoris | Filed in Astronomy

Finally it took me many more days that expected to share something after my relocation (due to some “issues”, but most probably because I try to enjoy the new place !!?!??!). Although vacation period for most I was working in and out of the office.

...and that will be on the left !

… which is exactly on the left side!