SN 2002ap: Nearest Hypernova!?

CCD image of SN 2002ap (by Y. Sano)

Descovery of a very bright supernova

On January 24, an apparently very bright supernova in M74 was discovered by Y. Hirose at 14.5mag and the object was rising to 13.7mag on January 30. The position of the object is about 258" west and 108" south of the face-on spiral galaxy M74 = NGC 628 (vsnet-campaign-sn 328, vsnet-campaign-sn2002ap 1, 2, 3, 4, 5, 7, 8). P. Vreeswijk et al. analyzed the pre-outburst image and revealed that the SN is not coincident with the V = 21.2 object which was proposed as a possible progenitor. There is no object in the pre-discovery images at the SN position, to limiting magnitudes V = 22.0 (vsnet-campaign-sn2002ap 87, 88).

Hypernova with a gamma-ray burst??

H. Yamaoka reported that spectra taken by Bisei, Gunma, ESO, and Wise Obs. team showed features similar to type Ib/c, or hypernova (vsnet-campaign-sn2002ap 11, 12, 13, 14, 15, 20, 32, 33, 46, 50, vsnet-campaign-sn 332, 333, 335). J. Deng reported that the expansion velocity of the ejected matter was quite fast and such large energy supports its hypernova nature (vsnet-campaign-sn2002ap 23). As well as GRB 980425 with SN 1998bw, it was suspected that this supernova might be associated with a gamma-ray burst (vsnet-campaign-sn2002ap 16, 17). Hurley er al. reported that, between January 21 and January 29, 2002, no burst which could be localized by the IPN was found to have a source position in any way consistent with that of the supernova (vsnet-campaign-sn2002ap 161). Following to this report, A. Gal-Yam et al. estimated the peak time of U- and B-band flux of SN 2002ap, and reported that the GRB trigger might occur before January 21 and is likely to have been missed by Hurley et al. (GCN 1252) (vsnet-campaign-sn2002ap 200). According to IAUC 7825, its spectrum during a fading stage was very similar to hypernova SN 1997ef about 2 weeks after explosion (vsnet-campaign-sn 345).

Fading stage

L. Cook reported on February 10 that the object continued brightening in I and R, but started fading in V. The star was getting redder (vsnet-campaign-sn2002ap 116). L. Wang et al. reported that their spectroplarimetry revealed a sharp change of the degree of polarization by more than 1 percent. The polarization of this particular feature may provide important clues of the structure of the supernova envelope (vsnet-campaign-sn2002ap 76, 56). The fading became rapider in mid-February (vsnet-campaign-sn2002ap 144). The object somewhat recovered from the rapid fading on February 17 (vsnet-campaign-sn2002ap 145, 146, 147). Lauroesch et al. performed spectroscopy and reported clear detections of interstellar NaI and CaII in both the Milky Way and M74 (vsnet-campaign-sn2002ap 124). Klose et al. also performed spectroscopy and showed the supernova light was nearly unaffected by dust in M 74 (vsnet-campaign-sn2002ap 125). The fading rate appears to become more rapid since the end of February (vsnet-campaign-sn2002ap 181, 182, 183, 184, 187). A. Henden reported V=16,4 with red (V-R) but blue(R-I) on June 27, usually indicative of strong Halpha emission (vsnet-campaign-sn2002ap 202). A. Henden reported his observations of V=17.747 and B-V=0.327 on August 31 (vsnet-campaign-sn2002ap 204). The object was reported to have experienced a sudden rapid fading on November 26 (vsnet-campaign-sn2002ap 206).

Other articles:
vsnet-campaign-sn2002ap 18, 19, 21, 22, 24, 26, 27, 28, 29, 34, 36, 37, 39, 40, 41, 44, 45, 47, 48, 49, 51, 52, 53, 53, 54, 55, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 79, 80, 81, 82, 83, 84, 85, 86, 89, 90, 91, 92, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 114, 115, 117, 118, 119, 120, 121, 122, 123, 126, 127, 128, 129, 130, 131, 133, 135, 136, 137, 138, 139, 140, 141, 142, 143, 147, 148, 149, 150, 151, 153, 155, 159, 162, 163, 164, 165, 166, 167, 168, 169, 170, 173, 174, 175, 176, 177, 178, 179, 180, 186, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 201, 203, 205, vsnet-campaign-sn 331, 352

Links:

General Information about This Object

Return to HomePage

Return to Daisaku Nogami's page

vsnet-adm@kusastro.kyoto-u.ac.jp