# NGC 300

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**NGC 300** (also known as **Caldwell 70** or the **Sculptor Pinwheel Galaxy**[3]) is a [spiral galaxy](/source/Spiral_galaxy) in the [constellation](/source/Constellation) [Sculptor](/source/Sculptor_(constellation)). It was discovered on 5 August 1826 by [Scottish](/source/Scotland) astronomer [James Dunlop](/source/James_Dunlop).[4] It is one of the closest galaxies to the [Local Group](/source/Local_Group), and it most likely lies between the latter and the [Sculptor Group](/source/Sculptor_Group). It is the brightest of the five main spirals in the direction of the Sculptor Group.[2] It is inclined at an angle of 42° when viewed from [Earth](/source/Earth) and shares many characteristics of the [Triangulum Galaxy](/source/Triangulum_Galaxy).[5] It is about 94,000 light-years in diameter, somewhat smaller than the [Milky Way](/source/Milky_Way), and has an estimated mass of (2.9 ± 0.2) × 1010 .[6][7]

## Nearby galaxies and group information

NGC 300 and the [Magellanic type](/source/Magellanic_spiral_galaxy) [barred spiral galaxy](/source/Barred_spiral_galaxy) [NGC 55](/source/NGC_55) have traditionally been identified as members of the [Sculptor Group](/source/Sculptor_Group), a nearby [group of galaxies](/source/Group_of_galaxies) in the constellation of the same name. However, recent distance measurements indicate that these two galaxies actually lie in the foreground.[8] It is likely that NGC 300 and NGC 55 form a gravitationally bound pair.[9]

The dwarf galaxy [Sculptor C](/source/Sculptor_C) is located about 6.65 million light-years (2.04 [megaparsecs](/source/Megaparsec)) away from the Sun, and is very likely a [satellite galaxy](/source/Satellite_galaxy) of NGC 300. Sculptor C has an absolute magnitude of about −9.1 which is typical for other recently discovered ultra-faint dwarf galaxies.[10]

## Distance estimates

In 1986, [Allan Sandage](/source/Allan_Sandage) estimated the distance to NGC 300 to be 5.41 [Mly](/source/Lightyear) (1.66 [Mpc](/source/Megaparsec)).[11] By 1992, this had been updated to 6.9 Mly (2.1 Mpc) by Freedman et al.[2] In 2006, this was revised by Karachentsev et al. to be 7.0 ± 0.3 Mly (2.15 ± 0.10 Mpc).[12] At about the same time, the [tip of the red giant branch](/source/Tip_of_the_red_giant_branch) (TRGB) method was used to produce an estimate of 5.9 ± 0.4 Mly (1.82 ± 0.13 Mpc) using edge detection and 6.1 ± 0.4 Mly (1.87 ± 0.12 Mpc) using maximum likelihood.[2] These results were consistent with estimates using near-infrared photometry of [Cepheid variables](/source/Cepheid_variable) by Gieren et al. 2005 that provided an estimate of 6.1 ± 0.2 Mly (1.88 ± 0.07 Mpc).[2] Combining the recent TRGB and Cepheid estimates the distance to NGC 300 is estimated at 6.07 ± 0.23 Mly (1.86 ± 0.07 Mpc).

## Transient Events

AT 2019qyl was discovered by the *Distance Less Than 40 Mpc Survey* (DLT40) on 26 September 2019, at magnitude 17.1. It was initially classified as a type IIn/LBV,[13] but later analysis classified the star as a classical [nova](/source/Nova).[14]

SN 2010da (type LBV, mag. 16) was discovered by Monard on 23 May 2010.[15][16] The optical transient was detected 15".9 west and 16".8 north the center of the galaxy at coordinates 00 55 04.86 −37 41 43.7.[17]

Two sets of independent follow-up spectroscopy data suggested that this was again another optical transient rather than a supernova, possibly an outbursting [luminous blue variable](/source/Luminous_blue_variable) star according to one spectrum,[18][19] as earlier predicted from the nature of the candidate mid-infrared progenitor.[20] The transient faded by 0.5–0.7 mag in 9 days, much faster than the 2008 transient in NGC 300.[21]

SN 2020acli ([type IIn-pec](/source/Type_II_supernova), mag. 18.4205) was discovered by the *Distance Less Than 40 Mpc Survey* (DLT40) on 12 December 2020.[22]

AT 2024oth (type unknown, mag. 19.85) was discovered by [BlackGEM](/source/BlackGEM) on 27 June 2024.[23]

AT 2024txt (type unknown, mag. 19.77) was discovered by [Pan-STARRS](/source/Pan-STARRS) on 29 July 2024.[24]

### NGC 300-OT

On a [CCD](/source/Charge-coupled_device) image obtained on 14 May 2008, amateur astronomer L.A.G. Berto Monard discovered a bright [optical transient](/source/Optical_transient) (OT) in NGC 300 that is designated NGC 300-OT.[25][26] It is located at [RA](/source/Right_ascension): and [DEC](/source/Declination): [27] in a [spiral arm](/source/Spiral_arm) containing active star formation.[28] Its broad-band magnitude was 14.3 in that image. An earlier image (from 24 April 2008), taken just after NGC 300 reemerged from behind the [Sun](/source/Sun), evidenced an already brightening OT at ~16.3 magnitude.[28] No brightening was detected on a 8 February 2008 image, nor on any earlier ones.[28] The transient's peak measured magnitude was 14.69 on 15 May 2008.[28]

At discovery, the transient had an absolute magnitude of MV ≈ −13, making it faint in comparison to a typical [core-collapse supernova](/source/Core-collapse_supernova) but bright in comparison to a [classical nova](/source/Classical_nova).[26][28] Additionally, the photometric and spectroscopic properties of the OT imply that it is not a [luminous blue variable](/source/Luminous_blue_variable) either.[28] Since its peak, brightness dropped smoothly through September 2008 while becoming continuously redder.[28] After September 2008, brightness continued to fall at a lower rate in the optical spectrum but with strong [Hα](/source/Hydrogen_alpha) emissions.[28] Further, the optical spectrum is mostly made up of fairly narrow [Hydrogen Balmer](/source/Hydrogen_Balmer) and Ca II emission lines coupled with strong Ca II H&K absorption.[26] Research into historical [Hubble](/source/Hubble_Space_Telescope) images provide an accurate upper bound on the progenitor star's brightness.[26] This suggested a low-mass [main sequence](/source/Main_sequence) star as progenitor with the transient resulting from a stellar merger similar to red Galactic nova [V838 Monocerotis](/source/V838_Monocerotis).[26] Analysis of historical images of the area of the OT suggest with 70% certainty that the progenitor formed in a burst of stars around 8–13 Myr ago and implies the progenitor's mass to be 12–25 [M☉](/source/Solar_mass) assuming the OT is due to an evolving massive star.[27]

However, in 2008 a bright [mid-infrared](/source/Mid-infrared) progenitor to the transient was discovered in historical [Spitzer](/source/Spitzer_Space_Telescope) data. This was a star that was obscured by dust, with energy distribution analogous to a [black-body](/source/Black-body) of *R* ≈ 300 [AU](/source/Astronomical_units) and radiating at *T* ≈ 300 [K](/source/Kelvin) with *L*bol ≈ ×106 [*L*☉](/source/Solar_luminosity). This demonstrated that the transient was associated with an energetic explosion of a low-mass ≈ 10 M☉ star. The transient's low luminosity as compared to typical core-collapse supernova, combined with its spectral attributes and dust covered properties, make it nearly identical to [NGG 6946](/source/NGC_6946)'s [SN 2008S](/source/SN_2008S).[26]

The spectrum of NGC 300-OT observed with Spitzer shows strong, broad emission features at 8 μm and 12 μm. Such features are also seen in Galactic [carbon-rich](/source/Carbon_star) [protoplanetary nebulae](/source/Protoplanetary_nebulae).[26]

On 19 April 2025, NGC 300-OT was classified as an Intermediate-Luminosity Red Transient (ILRT).[29]

## Astronomical objects

### Binary black hole system

An [x-ray](/source/X-ray_astronomy) source in NGC 300 is designated NGC 300 X-1.[30] Astronomers speculate that NGC 300 X-1 is a new kind of [Wolf-Rayet](/source/Wolf%E2%80%93Rayet_star) + [stellar black hole](/source/Stellar_black_hole) [binary system](/source/Binary_system_(astronomy)) similar to the confirmed such system [IC 10](/source/IC_10) X-1.[30] Their shared properties include an [orbital period](/source/Orbital_period) of 32.8 hours. The black hole has a mass of 17 ± 4 and the WR star has a mass of 26 ± 7 . Both objects orbit each other at a distance of about 18.2 .[31]

### WO star

There is an oxygen-sequence Wolf–Rayet star (WO4 type), known as STWR 13, located in one of the bright H II regions in NGC 300.[32]

## Notes

1. Average (1.845 ± 0.125, 1.86 ± 0.07) = ((1.845 + 1.86) / 2) ± ((0.1252 + 0.072)0.5 / 2) = 1.86 ± 0.07

## See also

- [List of NGC objects (1–1000)](/source/List_of_NGC_objects_(1%E2%80%931000))

## References

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1. Binder, Breanna A.; Sy, Janelle M.; Eracleous, Michael; Christodoulou, Dimitris M.; Bhattacharya, Sayantan; Cappallo, Rigel; Laycock, Silas; Plucinsky, Paul P.; Williams, Benjamin F. (2021-03-01). "The Wolf–Rayet + Black Hole Binary NGC 300 X-1: What is the Mass of the Black Hole?". *The Astrophysical Journal*. **910** (1): 74. [arXiv:2102.07065](https://arxiv.org/abs/2102.07065). [Bibcode:2021ApJ...910...74B](https://ui.adsabs.harvard.edu/abs/2021ApJ...910...74B). [doi:10.3847/1538-4357/abe6a9](https://doi.org/10.3847/1538-4357/abe6a9). [ISSN 0004-637X](https://www.worldcat.org/issn/0004-637X)

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## External links

- Confirmation image of [SN 2010da](https://web.archive.org/web/20110927114126/http://www.supernovae.net/sn2010/n300s2.jpg) (2010-05-24) / [Wikisky DSS2 zoom-in of same region](http://www.wikisky.org/?ra=0.9161420290060076&de=-37.694394782755666&zoom=11&show_grid=1&show_constellation_lines=1&show_constellation_boundaries=1&show_const_names=0&show_galaxies=1&show_box=1&box_ra=0.9180167&box_de=-37.695473&box_width=50&box_height=50&img_source=DSS2)

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Adapted from the Wikipedia article [NGC 300](https://en.wikipedia.org/wiki/NGC_300) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/NGC_300?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.