Monitoring of the optical and 2.5-11.7 μm spectrum and mid-IR imaging of the Seyfert 1 galaxy Mrk 279 with ISO

M. Santos-Lleó*, J. Clavel, B. Schulz, B. Altieri, P. Barr, D. Alloin, P. Berlind, R. Bertram, D. M. Crenshaw, R. A. Edelson, U. Giveon, K. Horne, J. P. Huchra, S. Kaspi, G. A. Kriss, J. H. Krolik, M. A. Malkan, Yu F. Malkov, H. Netzer, P. T. O'BrienB. M. Peterson, R. W. Pogge, V. I. Pronik, B. C. Qian, G. A. Reichert, P. M. Rodríguez-Pascual, S. G. Sergeev, J. Tao, S. Tokarz, R. M. Wagner, W. Wamsteker, B. J. Wilkes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 μm spectrum. Contemporaneous optical photometric and spectrophotometric observations are also presented. The galaxy appears as a point-like source at the resolution of the ISOCAM instrument (4-5″). The 2.5-11.7 μm average spectrum of the nucleus in Mrk 279 shows a strong power law continuum with α = -0.80 ± 0.05 (Fv ∝ vα) and weak PAH emission features. The Mrk 279 spectral energy distribution shows a mid-IR bump, which extends from 2 to 15-20 μm. The mid-IR bump is consistent with thermal emission from dust grains at a distance of ≳ 100 lt-d. No significant variations of the mid-IR flux have been detected during our observing campaign, consistent with the relatively low amplitude (∼10% rms) of the optical variability during the campaign. The time delay for Hβ line emission in response to the optical continuum variations is τ = 16.7-5.6+5.3 days, consistent with previous measurements.

Original languageEnglish
Pages (from-to)57-64
Number of pages8
JournalAstronomy and Astrophysics
Issue number1
StatePublished - 2001


  • Galaxies: Seyfert
  • Galaxies: active
  • Galaxies: individual: Mrk 279
  • Galaxies: nuclei
  • Infrared: galaxies


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