Deep Sky Object in Spring
Supernova 2014J in M82


Date & Time: Feb 18 2012, from 25:52 to 26:22 JST(+0900)Jan 31 2014, from 27:15 to 27:31 JST(+0900)
Composed 6 images with 6min. exposedComposed 6 images with 3min. exposed
Optical: Meade 25cm(10") Schmidt-Cassegrain
with reducer (f=1600mm, F6.3)		VIXEN 20cm(7.9") VISAC
with reducer (f=1278mm, F6.4)
Auto-guided with Meade LX200 Equatorial
& Pictor 201XT		Auto-guided with TAKAHASHI EM-200 Equatorial
Camera: Canon EOS 550D (Remodeled)
(ISO3200)		Canon EOS 600D (Remodeled)
(ISO3200)
Location: Ooizumi, Hokuto city, Yamanashi pref.Hiraiso, Hitachi-naka city, Ibaraki pref.


On Jan 21, 2014, a supernova 2014J appeared in M82, one of the Bode's Galaxy in Ursa Major, was discovered at London University Observatory. It has been comfirmed that the supernova exploded in middle of the January. I estimated the brightness in that night of 10.3rd magnitude by comparing with brightness of surrounding stars. It's very rare sky event that the supernova appears in short distance galaxy at most 10 millions light years or so, SN2014J is the first one of such a kind since the SN1993J that appeared in a neighboring galaxy of M81 in 1993.


Spectral profiles of SN2014J (Feb 22 & Mar 22, 2014) and brightness change



SN2014J on Feb 22 & slit position (north in up)
Date & Time: Feb 22 2014, from 23:27 to 23:37 JST(+0900), 5min.×2shot
Mar 22 2014, from 20:07 to 20:27 JST(+0900), 10min.×2shot
Optical: Meade 25cm(10") Schmidt Cassegrain (f=2500mm, F10.0)
with SBIG DSS7 Spectrometer
Auto-guided with Meade LX200 Equatorial & Pictor 201 XT
Cooled CCD Camera: SBIG ST-402ME (Temp.: -25°C(Feb 22), -30°(Mar 22))
Location: Ooizumi, Hokuto city, Yamanashi pref.

Upper strip: taken spectrogram, Lower strip: stretched 4-pixel-width & pseudo-colored image


Absorption lineSi IISi I
Observed WL, λm6140 Å5720 Å
 WL in literature, λ06355 Å5948 Å
Blue shift, z3.38×10-23.83×10-2
Closing velocity, V9.98×103 km/s1.13×104 km/s
Expanding velocity, V'1.04×104 km/s1.17×104 km/s

  z= (λ0-λm)/λ0
  V= c*((1+z)2-1)/((1+z)2+1)
  V'= V + 400 km/s (Recession velocity of M82)
An upper figure shows you the observed spectrograms and spectral profiles of SN2014J 38 days (Feb 22) and 66 days (Mar 22) later of its explosion. Those profiles have been indicated with white and yellow lines respectively. The profiles show no absorptions of hydrogen or helium, while have the broad absorption lines of silicon (Si I & Si II) and iron atoms. It's the typical characteristics of the type Ia supernovae. It explodes due to the excursion of nuclear reaction when exceeded the critical mass of a white dwarf that gained stellar matter from a companion star with which the dwarf formed a binary star system. Furthermore steep absorption lines of sodium (Na I) atoms can be observed in the profiles, it's considered that the line is derived from the inter-stellar gaseous matter in the galaxy of M82.
We can estimate the radial closing (=expanding) velocity of the supernova explosion from the observed two wavelengths of ionized silicon (Si II) at 6355Å and neutral silicon (Si I) at 5948Å. A table in right has listed and indicated the estimated expanding velocities calculated from blue shifts of these two wavelengths of absorption lines in their local minima observed on Feb 22. The active galaxy of M82 has conspicuous emission lines of hydrogen atoms in its nucleus, the recession velocity of the galaxy due to the cosmic expansion can be estimated from the red shifts of the lines (estimated results). The value has about 400km/s, the expanding velocity of the SN2014J including the correction, can be calculated as about 10,000 to 12,000km/s.
Two profiles on Feb 22 and Mar 22 have a difference in the Doppler distributions of the ionized silicon atoms at 6355Å. In the profile on Mar 22, the absorption at 6140Å looks weaker than that on Feb 22, while the absorption around 6355Å, original wavelength without the Doppler shift, can be observed. It seems that the absorption of Si II has divided in two parts. It's considered that the inner matter with lower expanding velocity has become observable due to the dilution of the supernova.
A lower figure shows the brightness change of SN2014J estimated from the optical images. The supernova had the maximum brightness with 10.2nd magnitude on Feb 2, and is getting dimmer gradually, down about 2nd magnitude on Mar 22.

Brightness change of SN2014J

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Copyright(c) 2014 by Naoyuki Kurita, All rights reserved.
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