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Post Info TOPIC: NGC3190


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Supernova 2002cv

Title: SN 2002cv: A Heavily Obscured Type Ia Supernova
Authors: N. Elias-Rosa, S. Benetti, M. Turatto, E. Cappellaro, S. Valenti, J. E. Beckman, A. Di Paola, M. Dolci, A.V. Filippenko, R.J. Foley, K. Krisciunas, W. Li, W.P.S. Meikle, A. Pastorello, G. Valentini, W. Hillebrandt

We present VRIJHK photometry, and optical and near-infrared spectroscopy, of the heavily extinguished Type Ia supernova (SN) 2002cv, located in NGC 3190, which is also the parent galaxy of the Type Ia SN 2002bo. SN 2002cv, not visible in the blue, has a total visual extinction of 8.74 0.21 mag. In spite of this we were able to obtain the light curves between -10 and +207 days from the maximum in the I band, and also to follow the spectral evolution, deriving its key parameters. We found the peak I-band brightness to be Imax = 16.57 0.10 mag, the maximum absolute I magnitude to be MmaxI = -18.79 0.20, and the parameter dm15(B) specifying the width of the B-band light curve to be 1.46 0.17 mag. The latter was derived using the relations between this parameter and dm40(I) and the time interval dtmax(I) between the two maxima in the I-band light curve. As has been found for previously observed, highly extinguished SNe Ia, a small value of 1.59 0.07 was obtained here for the ratio Rv of the total-to-selective extinction ratio for SN 2002cv, which implies a small mean size for the grains along the line of sight toward us. Since it was found for SN 2002bo a canonical value of 3.1, here we present a clear evidence of different dust properties inside NGC 3190.

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ESO's Very Large Telescope, equipped with the multi-mode FORS instrument, took an image of NGC 3190, a galaxy so distorted that astronomers gave it two names. And as if to prove them right, in 2002 it fired off, almost simultaneously, two stellar explosions, a very rare event.

This beautiful edge-on spiral galaxy with tightly wound arms and a warped shape that makes it resemble a gigantic potato crisp lies in the constellation Leo ('the Lion') and is approximately 70 million light years away. It is the dominant member of a small group of galaxies known as Hickson 44, named after the Canadian astronomer, Paul Hickson. In addition to NGC 3190, Hickson 44 consists of one elliptical and two spiral galaxies. These are, however, slightly out of the field of view and therefore not visible here.

ngc3190b The Spiral Galaxy NGC 3190 Credit ESO

Signs of tidal interactions are visible in the twisted dust lane of NGC 3190. This distortion initially misled astronomers into assigning a separate name for the southwestern side, NGC 3189, although NGC 3190 is the favoured designation. NGC 3190 has an 'Active Galactic Nucleus', and as such, the bright, compact nucleus is thought to host a supermassive black hole. In March 2002, a new supernova (SN 2002bo) was found in between the 'V' of the dust lanes in the southeastern part of NGC 3190. It was discovered independently by the Brazilian and Japanese amateur astronomers, Paulo Cacella and Yoji Hirose. SN 2002bo was caught almost two weeks before reaching its maximum brightness, allowing astronomers to study its evolution. It has been the subject of intense monitoring by a world-wide network of telescopes.

The conclusion was that SN 2002bo is a rather unusual Type Ia supernova. The image presented here was taken in March 2003, i.e. about a year after the maximum of the supernova which is 50 times fainter on the image than a year before. While observing SN 2002bo in May 2002, a group of Italian astronomers discovered another supernova, SN 2002cv, on the other side of NGC 3190. Two supernovae of this type appearing nearly simultaneously in the same galaxy is a rare event, as normally astronomers expect only one such event per century in a galaxy. SN 2002cv was best visible at infrared wavelengths as it was superimposed on the dust lane of NGC 3190, and therefore hidden by a large quantity of dust. In fact, this supernova holds the record for the most obscured Type Ia event. The image was obtained with a total exposure time of 14 minutes only. Yet, with the amazing power of the Very Large Telescope, it reveals a large zoo of galaxies of varying morphologies.

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