Would eruption of dwarf nova in M5 cause M5 to brighten enough to be noticeable?

[gdaniels99]

Would an eruption of the dwarf nova in M5 be noticeable on earth by a naked eye observer? What magnitude eruption would be required for it to cause M5 to noticeably grow brighter? Are there any historical records of M5 ever brightening?

[StupendousMan]

Let's see. The globular cluster M5 has an apparent magnitude of +6.6, and a distance of about 7.5 kpc. The distance modulus is (m - M) = 5 log d - 5 = 14.4 mag. So, we can compute the absolute magnitude of the cluster: about -7.7. That's pretty typical for a globular cluster.

How luminous are dwarf novae? Much less luminous than ordinary novae. This paper by Joe Patterson,

http://arxiv.org/pdf/0903.1006

shows that dwarf novae have quite a range of absolute magnitudes, but a typical value is +4. That means that a typical dwarf nova provides something like 1/200,000 the light of the globular cluster M5.

So, no, a dwarf nova would not change the luminosity of M5 to any significant extent.

[chornedsnorkack]

For comparison, how about an ordinary nova?

Bright recent novae:
V603 Aquilae, 1918 - -1,4, about 800 ly/250 pc - about -8,4, outshining M5, and probably going as far as visible.
GK Persei, 1901 - +0,2, about 1500 ly/460 pc - about -8
CP Puppis, 1942 - +0,3, but at 3700 ly/1140 pc - about -10
RR Pictoris, 1925 - +1,2, unknown distance
DQ Herculis, 1934 - +1,5, but at just 97 pc means about -3,4
V1500 Cygni, 1975 - +1,7, at 6400 ly/1950 pc - about -10,2
V476 Cygni, 1920 - +2,0, unknown distance
CP Lacertae, 1936 - +2,1, unknown distance
V382 Velorum, 1999 - +2,6, unknown distance.