V906 Carinae, also known as Nova Carinae 2018, was a

nova A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramat ...

in the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

galaxy which appeared in the constellation

Carina Carina may refer to: Places Australia * Carina, Queensland, a suburb in Brisbane * Carina Heights, Queensland, a suburb in Brisbane * Carina, Victoria, a locality in Mildura Serbia * Carina, Osečina, a village in the Kolubara District ...

, near the 5th magnitude star HD 92063. It was discovered on images taken on 20.32 March 2018 by the

All Sky Automated Survey for SuperNovae The All Sky Automated Survey for SuperNovae (ASAS-SN) is an automated program to search for new supernovae and other astronomical transients, headed by astronomers from the Ohio State University, including Christopher Kochanek and Krzysztof Stane ...

(ASAS-SN] telescope at the

Cerro Tololo Inter-American Observatory The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about to the southeast. It is approximately ...

. The ASAS-SN group assigned the name ASASSN-18fv to the object. The discovery image was saturated, allowing researchers to determine only that the object was brighter than

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

10. An earlier image obtained by ASAS-SN on 26.32 March 2018 showed the nova was a magnitude ~10.4 object at that time, and the object was not detected on ASAS-SN images taken on 15.34 March 2018 and earlier. V906 Carinae was featured in the

Astronomy Picture of the Day Astronomy Picture of the Day (APOD) is a website provided by NASA and Michigan Technological University (MTU). According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation wr ...

on 25 March 2018. Pre-discovery images of V906 Carinae were matched to a star of

Gaia In Greek mythology, Gaia (; from Ancient Greek , a poetical form of , 'land' or 'earth'),, , . also spelled Gaea , is the personification of the Earth and one of the Greek primordial deities. Gaia is the ancestral mother—sometimes parthen ...

magnitude 20.1. On 21 March 2018, it had brightened to a Gaia magnitude 7.80 (

visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

7.45), and to magnitude 6.62 later the same day. Also on 21 March 2018, long exposure spectrographic measurements of ASASSN-18fv, specifically in the 3800 Å to 7300Å range, were captured using CCD imaging. Detailed analysis of the spectral data confirmed that ASASSN-18fv exhibited characteristics of a classical nova. All novae are binary stars, with a "donor" star orbiting a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

. The two stars are so close to each other that material is transferred from the donor to the white dwarf. In the case of V906 Carinae, data from the

Transiting Exoplanet Survey Satellite Transiting Exoplanet Survey Satellite (TESS, Explorer 95 or MIDEX-7) is a space telescope for NASA's Explorer program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the ''Keple ...

suggests that the binary system has an orbital period of either 1.641 hours or twice that value. The mass of the white dwarf has been estimated to be , and the donor is believed to be a dwarf of

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

K or M and a mass of . One of the stars monitored by the Bright-star Target Explorer (BRITE)

nanosatellite A small satellite, miniaturized satellite, or smallsat is a satellite of low mass and size, usually under . While all such satellites can be referred to as "small", different classifications are used to categorize them based on mass. Satellites ca ...

constellation was HD 92063. V906 Carinae was close enough to that star to be serendipitously observed by BRITE. In the BRITE data, the nova's maximum brightness occurred on 14 April 2018. BRIGHT provided a measurement of the nova's brightness every 1.6 hours, allowing the fluctuations near the peak of the outburst to be seen clearly. There were eight post-maximum flares with amplitudes of a few tenths of a magnitude each of which lasted 1 to 3 days. These flares in the visible portion of the EM spectrum occurred at the same times that γ-ray flares were seen by Fermi-LAT. Because the γ-ray flares are believed to arise from shocks in the ejected material, their correlation with visible flares suggests that most of the visible light from the nova may be produced in shocks, rather than the nuclear burning on the white dwarf's surface.

References

External links

* {{DEFAULTSORT:V906 Carinae Novae Carina (constellation) 20180320 Carinae, V906