DQ Herculis

DQ Herculis

File:DQHerNebula.png RGB composite color image of the shell surrounding the nova DQ Her, made from three narrow band images: Blue = 4800Å, green = Hα at 6563 Å and red = [NII] at 6583 Å. From Santamaria et al. 2020
Observation data Epoch J2000      Equinox J2000
Constellation	Hercules
Right ascension	Template:RA
Declination	Template:Dec
Apparent magnitude (V)	1.5 - 15.16
Characteristics
Spectral type	DBe + M2V
Variable type	DQ Her
Astrometry
Proper motion (μ)	RA: −0.948 mas/yr Dec.: +12.423 mas/yr
Parallax (π)	1.9975±0.0237 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−6.94
Orbit
Period (P)	0.1936208977 ± 0.0000000017 d
Semi-major axis (a)	0.003 AU
Inclination (i)	Template:Val°
Details
A
Mass	0.6 Template:Solar mass
Radius	0.0121 Template:Solar radius
B
Mass	0.4 Template:Solar mass
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist, CDS 959, PLX 4164, AN 452.1934, GCRV 10587, CSI+45-18061, SBC7 665, AAVSO 1804+45
Database references
SIMBAD	data

File:DQHerLightCurve.png

The light curve of DQ Herculis, from AAVSO data. The pronounced "dust dip" roughly four months after peak brightness was caused by dust forming as the ejected shell expanded and cooled.

DQ Herculis, or Nova Herculis 1934, was a slow, bright nova occurring in the northern constellation of Hercules in December 1934. This cataclysmic variable star was discovered on 13 December 1934 by J. P. M. Prentice from Stowmarket, Suffolk. It reached peak brightness on 22 December 1934 with an apparent magnitude of 1.5. The nova remained visible to the naked eye for several months.

This is a binary star system consisting of a white dwarf primary with an estimated 60% of the mass of the Sun and a red dwarf secondary with 40% of the Sun's mass. They orbit each other tightly with a period of Template:Convert. The system shows orbital period variation, possibly due to the presence of a third body. The orbital plane of the pair is inclined by an angle of 86.5° to the line of sight from the Earth, causing the white dwarf to undergo a deep eclipse every orbit.

DQ Herculis is the prototype for a category of cataclysmic variable stars called intermediate polars. The red dwarf has filled its Roche lobe and matter is being drawn off at the rate of 2.7 × 10⁻⁹ Template:Solar mass yr⁻¹, forming an accretion disk orbiting the primary. This disk has inferred temperatures ranging from 5,000 to Template:Val. A bright spot in the inner disk appears to pulsate with a 71-second period. In this class of variables, the white dwarf is magnetized, directing infalling matter onto the magnetic poles.

File:DQHerNebulaExpanding.png

Two images of the shell surrounding DQ Hercules taken 21 years apart, showing the nebula's expansion. Both were taken with Hα filters, left at the William Herschel Telescope, and right with the Nordic Optical Telescope.

The shell of ejected material from the nova outburst is visible as an emission nebula, similar in appearance to a planetary nebula. This roughly elliptical nebula had a size of 32.0 × 24.2 arc seconds as of 2018, and it is expanding at a rate of about 0.16 arc seconds per year.

In popular culture

File:DQHerLocation.png

The location of nova DQ Herculis (circled in red)

The nova was one of the brightest objects observable in the night sky. In addition to scientific articles, and received significant coverage in popular news publications. Brad Ricca, an English professor at Case Western Reserve University, has suggested that Nova Herculis may have influenced the development of the origin story of the comic book superhero Superman.

External links

• http://www.daviddarling.info/encyclopedia/N/Nova_Herculis_1934.html