У сверхновой 2008ax в NGC 4490 обнаружен объект прородитель!

[ctac]

 Сверхновая 2008ax была открыта в ночь 3/4 марта Lick Observatory Supernova Search и Koichi Itagaki в галактике NGC 4490.

 

 Модуль расстояния до галактики равен (m-M) =30^m, т.ч. при условии вспышки яркой сверхновой (M=-19^m) в максимуме блеска она могла бы достигнуть V=11^m.

 Но судя по спектру, сверхновая относится к II типу, возможно даже подобна самой близкой и слабой вспышке сверхновой 1987А (в Б.Магелановом облаке). Так что, ее абсолютная яркость в максимуме вспышке, по предположениям, не превзойдет V=14^m.
 Самое интересное, что был обнаружен объект прородидель данной вспышки сверхновой (B = 23.6 mag, V = 23.5 mag, I = 22.6 mag) на снимках Космического Телескопа Хаббл. Но пока нет 100% уверенности в том, что это именно тот объект, что вспыхнул.

 Координаты:  R.A. = 12h30m40s.80, Decl. = +41°38'14".5
 Блеск (6 марта):  V=15.6^m

 http://www.astronomerstelegram.org/?read=1417
 http://www.supernovae.net/snimages/

 

[BrainBug]

А я её(галактику!) снимал 18 февраля!

[ctac]

А я её(галактику!) снимал 18 февраля!

 Как близко было открытие! Всего на 2 недели позднее снять и вот оно!

[BrainBug]

А я её(галактику!) снимал 18 февраля!

Как близко было открытие! Всего на 2 недели позднее снять и вот оно!

А то! Обидно, однако!
С горя и за 8-е марта сегодня буду пить! 

[ctac]

 А 2008ax тем временем разгорелась до 14.0^m, став таким образом самой яркой из наблюдаемых на сегодня сверхновых.

[ctac]

SUPERNOVA 2008ax IN NGC 4490
   
     R. Chornock, A. V. Filippenko, W. Li, and R. J. Foley, University of
California, Berkeley, report that a spectrum of SN 2008ax (CBETs 1280, 1285)
obtained by A. Stockton (University of Hawaii) using the Keck I 10-m telescope
(+ LRIS; range 310-920 nm) on Mar. 9.6 UT reveals that the object has evolved
into a type-IIb supernova.  The spectrum is dominated by P-Cyg features of the
hydrogen Balmer series, Fe II, and Ca II, with the absorption minimum of
H-alpha blueshifted by roughly 17600 km/s.  In addition, notches have appeared
in the H-alpha emission profile near 645 and 682 nm, which are identified as
the incipient He I 667.8- and 706.5-nm absorptions indicative of a type-IIb
supernova.  The overall spectrum bears a strong resemblance to the type-IIb
supernova 1987K (Filippenko 1988, A.J. 96, 1941) near maximum light, but with
higher expansion velocities.  Furthermore, spectropolarimetry (range 415-695
nm) was obtained by E. C. Moran (Wesleyan University) and J. Hodge and K.
Merriman (University of California, Davis) using the Kast spectrograph on the
Shane 3-m telescope at Lick Observatory on Mar. 9.4.  The polarization data
show that SN 2008ax is strongly polarized, with a modulation of more than 3
percent across the H-alpha line.  Other type-IIb supernovae observed in the
past, such as 1993J (Hoeflich et al. 1996, Ap.J. 459, 307; Tran et al. 1997,
PASP 109, 489) and 1996cb (Wang et al. 2001, Ap.J. 550, 1030) have also shown
large intrinsic polarizations, while normal type-IIP supernovae usually show
little polarization at this early age (e.g., Leonard et al. 2001, Ap.J. 553,
861).  Further observations at all wavelengths are encouraged.
     Chornock et al. also report an improved estimate for the equivalent width
of the narrow Na I D absorption lines in the Keck ESI spectrum as reported on
CBET 1290.  The new measurement is about 0.18 nm, suggesting an E(B-V)
reddening of about 0.5 mag.  Adopting this new reddening and the other
information reported on CBET 1290, the possible progenitor of SN 2008ax has an
absolute magnitude of M(V) = -7.5 and colors of B-V = -0.4 and V-I = 0.1,
consistent with a bright blue supergiant star.  Note that the progenitor of
SN 1993J (Aldering et al. 1994, A.J. 107, 662; Van Dyk et al. 2002, PASP 114,
1322) has M(V) = -7.0 and is a yellow K2 Ia supergiant, so the possible
progenitor of SN 2008ax is more luminous and has a bluer color than that of
SN 1993J, if the assumed reddening is correct.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

2008 March 12                    (CBET 1298)              Daniel W. E. Green


 SUPERNOVA 2008ax IN NGC 4490
   
     C. J. Stockdale, Marquette University and University of Oklahoma; K. W.
Weiler, Naval Research Laboratory; S. Immler, Goddard Space Flight Center;
S. D. Van Dyk, Spitzer Science Center, California Institute of Technology;
N. Panagia, Space Telescope Science Institute and Observatory of Catania; J.
M. Marcaide, University of Valencia; D. Pooley, University of Wisconsin at
Madison; and R. A. Sramek, National Radio Astronomy Observatory, report the
detection of radio emission near the position of the type-IIP supernova
2008ax (cf. CBET 1280) with the Very Large Array radio telescope.  A flux
density of 1.19 +/- 0.07 mJy was measured at 8.46 GHz (wavelength 3.5 cm)
and 5.80 +/- 0.59 mJy at 22.46 GHz (wavelength 1.3 cm) on Mar. 7.54 UT.  The
measured position of the radio emission of R.A. = 12h30m40.s80, Decl. =
+41o38'14".9 (equinox 2000.0) is in good agreement with the measured
optical position (end figures 40s.84, 15".4) given on CBET 1286.  Re-
observation on Mar. 10.25 indicates that the flux density of the radio source
has risen to 3.94 +/- 0.23 mJy at 8.46 GHz and 6.74 +/- 0.70 mJy at 22.46 GHz,
indicating almost certain detection of radio emission from SN 2008ax.  The
inverted radio spectrum implies that the radio emission has likely been
caught on the rise.  Because of the unusual underluminous nature of SN 2008ax
(CBET 1285) and its resemblance in some characteristics to the peculiar type-
II supernova 1987A (CBETs 1285, 1290), the object warrants further study in
all wavelength bands.  Radio observations are continuing.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

2008 March 12                    (CBET 1299)              Daniel W. E. Green

[ctac]

Сверхновая 2008ax достигла блеска 13.0^m!