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Post Info TOPIC: NGC2403
Blobrana


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Caldwell 7
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NGC 2403 (also Caldwell 7, UGC 3918, PGC 21396) is a magnitude 8.9 intermediate spiral galaxy located 8 million light-years away in the constellation Camelopardalis.
The galaxy was discovered by William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Windsor Road, Slough, on the 1st November 1788.

NGC 2403 hosted Supernova 2004dj, and SuperNova Candidate 1954J

Right ascension 07h 36m 51.4s, Declination +65° 36' 09"

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Blobrana


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NGC 2403
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Title: The Nova Rate in NGC 2403
Authors: J. R. Franck, A. W. Shafter, K. Hornoch, K. A. Misselt

A multi-epoch H-alpha survey of the late-type spiral galaxy NGC 2403 has been completed in order to determine its nova rate. A total of 9 nova candidates were discovered in 48 nights of observation with two different telescopes over the period from February 2001 to April 2012. After making corrections for temporal coverage and spatial completeness, a nova rate of 2.0 (+0.5,-0.3) per year was determined. This rate corresponds to a luminosity-specific nova rate of 2.5±0.7 novae per year per 10^{10} solar luminosities in K. This value is consistent with that of the similar Hubble type galaxy, M33, and is typical of those of other galaxies with measured nova rates, which range from 1-3 novae per year per 10^{10} solar luminosities in K.

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Blobrana


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RE: NGC2403
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Title: Chandra and XMM-Newton discovery of the transient X-ray pulsar in the nearby spiral galaxy NGC2403
Authors: Sergey Trudolyubov (IGPP/UCR, IKI), William Priedhorsky (LANL), France Cordova (UCR)

We report on the discovery and analysis of the transient X-ray pulsar CXO/XMMU J073709.13+653544 detected in the 2004 August-October Chandra and XMM observations of the nearby spiral galaxy NGC2403. The source exhibits X-ray pulsations with a period P~18 s, a nearly sinusoidal pulse shape and pulsed fraction 46-70%. The source shows a rapid decrease of the pulsation period from 18.25 s on Aug. 9 to 17.93 s on Sep. 12 and 17.56 s on Oct. 3, 2004. The X-ray spectra of the source are hard and are well fitted with an absorbed simple power law of photon index 0.9~1.2. The X-ray properties of the source and the absence of an optical/UV counterpart allow us to identify CXO/XMMU J073709.13+653544 as accreting X-ray pulsar in NGC2403. The maximum unabsorbed luminosity of the source in the 0.3-7 keV range, ~2.6x10e38 erg/s at 3.2 Mpc, is at least 260 times higher than its quiescent luminosity. The corresponding luminosity in the 0.3-100 keV energy range could be as high as ~1.2x10e39 erg/s, assuming the typical pulsar energy spectrum with high-energy cut-off at 10-20 keV. The rate of decrease of the pulsation period of the source (-10e-7 s/s) is the fastest observed among accreting pulsars. The evolution of the pulsation period suggests that it is dominated by the intrinsic spin-up of the compact object. The accretion rate implied by X-ray luminosity of CXO/XMMU J073709.13+653544 could account for the observed spin-up rate, assuming that the X-ray source is powered by disk accretion onto highly magnetized neutron star. Based on the transient behaviour and overall X-ray properties of the source, we conclude that it could be an X-ray pulsar belonging to either a Be binary system or a low-mass system similar to GRO J1744-28.

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The clearest most complete image to date of the spiral galaxy NGC 2403 was taken by the Subaru Telescope, using its Suprime-Cam.
NGC 2403, at a distance of 10 million light years in the constellation Camelopardalis, is a Sc type galaxy, which has open spiral arms and a small nucleus. It is approximately half the mass of our own galaxy, the Milky Way, and has an abundance of neutral hydrogen gas.
In the spiral arms there are active star formation regions in red, clusters of young blue stars called OB associations, and darker regions called dust lanes where light is blocked by gas and dust within the galaxy.


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Position: RA=7h37m, Dec=+65d36m
Field of View: 26.7 x 21.3 arcmins
Credit Subaru Telescope.

In the last century, Edwin Hubble used NGC 2403 as evidence that more distant galaxies move more quickly away from us, now called Hubble's Law. It was also used to develop the Tully-Fisher relation, which states that there is a relation between a galaxy's rotational speed and its brightness. NGC 2403 has become an important standard galaxy when deciding the distances to other galaxies, as we recognize the vast expanse of space.

Larger galaxies are thought to have developed from the collision and merger of smaller galaxies. Mergers can leave enduring marks on a galaxy's halo, the most extended and generally spherical component of a galaxy. There is evidence that relatively young stars exist in the halo of NGC 2403, hinting at a recent merger with another galaxy. Astronomers are now studying this image to see if the colour and brightness of the stars in the halo of NGC 2403 will reveal conclusive evidence of past mergers.

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