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Browsing Aryabhatta Research Institute of Observational Sciences by Author "Srivastava, R. K."

Browsing Aryabhatta Research Institute of Observational Sciences by Author "Srivastava, R. K."

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  • An anlysis of the light changes of the eclipsing binary XY Ceti in the frequency-domain 
    Srivastava, R. K. (1987)
    The photoelectric observations of the eclipsing binary XY Ceti presented by us (see Srivastava and Padalia, 1975) have been analysed by Okazaki (1978) and Ramella et al.(1980). They presented different sets of elements ...
  • Brightness changes in P/Halley 
    Goraya, P. S.; Srivastava, R. K.; Uddin, W. (1988)
    Thirty photometric magnitudes, in each filter (UBV), of P/Halley (1982i) have been measured on 1986, January 12. They show short-term variability of about 0.15 magnitude. The present measurements show the active nature of ...
  • Ca II H and K and Hα emission variability in AR Lacerate 
    Goraya, P. S.; Srivastava, R. K. (1984)
    AE Lac (=BD + 45°3813) is a well known RS CVn type eclipsing binary system. Many interesting phenomena are associated with the system such as light curve variations, star spots and radio flares. Many investigators found ...
  • Constancy of period in TX Ceti 
    Srivastava, R. K. (1990)
    A slightly improved period (P = 0.ᵈ7408401) of the eclipsing binary system TX Ceti has been given, which is based on all available times of minima. The O-C diagrams based on the period given in PPEN (1980) and based on the ...
  • Constancy of period in XX leonis 
    Srivastava, R. K. (1994)
    An updated period study of XX Leonisgives a revisedperiod, P = 0ᵈ.970939, and indicates constancy of the period since its earliest observation.
  • CU Eridani - a suspected variable 
    Srivastava, J. B.; Srivastava, R. K. (1987)
    Photometric observations of CU Eridani, recently classified as non-variable, indicate it to be a variable star.
  • Delta Cap: a possible RS CVn binary 
    Srivastava, R. K. (1987)
    The eclipsing binary δ Cap (B-16°5943) was known to be a single line spectroscopic binary. Slipher (1906) first detected variable radial velocity in δ Cap. Crump (1921), Luyten (1936), Stewart (1958) and Batten (1961) ...
  • Detailed period study of Delta Capricorni 
    Srivastava, R. K. (1988)
    Detailed period study of the eclipsing binary system Delta Cap is presented. Available times of minima have been given. Period changes in different protions off the instant period trend. A new period of 1.ͩ0227789 has been ...
  • Disc system Delta Capricorni 
    Srivastava, R. K. (1988)
    First UBV photoelectric photometry of the eclipsing binary system δ Cap has been presented. An improved period of 1.ᵈ022766 has been given. The duration of primary eclipsing comes out to be more than double the duration ...
  • Eclipsing binary signatures in Zeta Capricorni 
    Srivastava, R. K. (1988)
    Zeta Capricorni (ζ Cap HD 204075) was shown to be a Barium line spectroscopic binary, possessing strong BaII line by Bohm-Vitense (1980), Smith et al.(1980), Culiver (1981) and Smith and Lambert (1984). ζ Cap is shown to ...
  • Flare features of AR Lacertae 
    Srivastava, R. K. (1986)
    BV optical flares of AR Lacertae, found in 1979 observations, are presented and their features are discussed. The effect of wave migration and the significance levels of flares originating around both eclipses have been ...
  • Flare like activity in AR Lacertae 
    Srivastava, R. K. (1983)
    The system AR Lac (=BD +45°3813 = HD 210334 = HV 2980 = HR 8448) is an interesting RS CVn binary. The system is known to e a radio sources (vide Hjellming and Blankenship, 1973; Gibson and Hiellming, 1974; Spangler et ...
  • Flare like activity of AR Lacertae in 1982 
    Srivastava, R. K. (1985)
    Investigations of the eclipsing binary system AR Lacertae have been reported earlier by author (cf. Srivastava, 1981; 1983s; 1983b; 1984; Goraya and Srivastava, 1984). AR Lac is a well known radio flaring sources. Some ...
  • HD 34409 - a delts scuti variable 
    Srivastava, R. K.; Arya, A. K. (1983)
    The star HD 34409 (=BD + 69d315) was reported to be a variable of small amplitude by Hilditch (1971). He also reported the spectral type of HD 34409 as F2 and indicated that the light variations of the star closely ...
  • Light variability in ɛ UMa 
    Srivastava, R. K. (1989)
    First U, B, and V observations of ɛ UMa are presented. Light curves show light variations of varying amplitude. Colour indices also show small colour variations.
  • Mass transfer in AR Lacertae 
    Srivastava, R. K. (1984)
    Evolutionary discussion shows that the possibility of AR Lac being in a semi-detached state of evolution cannot be ruled out. The period variations of AR Lac have been analysed using Biermann & Hall's (1973) model for a ...
  • Near-infrared observations and optical identifications of a few unassociated IRAS sources with dust shells 
    Lyengar, K. V. K.; Ghosh, S. K.; Rengarajan, T. N.; Verma, R. P.; Joshi, S. C.; Srivastava, R. K. (1989)
    We have carried out near infrared observations of twenty six unassociated IRAS sources with dust shells. Twenty of these belong to the group that have IRAS low resolution spectral characteristic (LRSCHAR = 4n), classified ...
  • Neglected binaries of special interest 
    Srivastava, R. K. (1998)
    Some binaries of special interest, observed at Uttar Pradesh State Observatory, Naini Tal, have been presented in this communication. Some of these binaries, although sufficiently bright, have not yet been investigated ...
  • A new period and period changes in VZ Hydrae 
    Srivastava, R. K. (1987)
    A new period (P=2.ͩ9042997) of the eclipsing binary system VZ Hydrae has been given, which is based on all the available times of minima. The period based on the photoelectric epochs has also been presented. The O-C diagram ...
  • A new period and period changes of GG Cassiopeiae 
    Srivastava, R. K. (1987)
    The O-C diagram of the eclipsing binary GG Cassiopeiae has been presented for the first time, and the period changes present in the system have been analysed. In all three period changes are noted. The strongest period ...

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