## Astronomy C

jonboyage
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### Re: Astronomy C

PM2017 wrote:
ashucha wrote:This may be a bit too specific but does anybody know what the apparent and absolute magnitude of DEM L241 (aka NGC 2029) is and where you got this information? Thanks!

This isn't anywhere close to perfect, but perhaps it's a reasonable estimate.

This paper says that the x-ray source has a luminosity $\approx 2 \times 10^{35} \mathrm{erg/s} = 2 \times 10^{28} \mathrm{W}$ . Converting that to absolute magnitude gives about 0.54

The same paper also mentions that the distance is about 50 kpc. Using the distance modulus, this gives an apparent magnitude of about 19.03

As for the entire remnant, Table 5 in the paper says that it has a luminosity of about $\approx 9.14 \times 10^{35} \mathrm{erg/s} = 9.14 \times 10^{28} \mathrm{W}$ . This would give an absolute magnitude of about -1.11 and apparent magnitude 17.385

Correct me if I'm wrong, but simbad seems to give an apparent magnitude of 12.29.

this would imply an absolute magnitude of -6.20, using the distance modulus (with d= 50,000 pc, from the aforementioned paper)

I would tend to believe PM2017 because later in the paper it says, "The bright optical counterpart, a V = 13.5 O5III(f) star, is
easily visible within the Head of the remnant." The star probably emits a lot of ionizing radiation and lights up, so-to-speak, the rest of the nebula. Note that SIMBAD lists the magnitude in the J band, which is infrared, so that makes sense.
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PM2017
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### Re: Astronomy C

jonboyage wrote:
PM2017 wrote:
Adi1008 wrote:This isn't anywhere close to perfect, but perhaps it's a reasonable estimate.

This paper says that the x-ray source has a luminosity $\approx 2 \times 10^{35} \mathrm{erg/s} = 2 \times 10^{28} \mathrm{W}$ . Converting that to absolute magnitude gives about 0.54

The same paper also mentions that the distance is about 50 kpc. Using the distance modulus, this gives an apparent magnitude of about 19.03

As for the entire remnant, Table 5 in the paper says that it has a luminosity of about $\approx 9.14 \times 10^{35} \mathrm{erg/s} = 9.14 \times 10^{28} \mathrm{W}$ . This would give an absolute magnitude of about -1.11 and apparent magnitude 17.385

Correct me if I'm wrong, but simbad seems to give an apparent magnitude of 12.29.

this would imply an absolute magnitude of -6.20, using the distance modulus (with d= 50,000 pc, from the aforementioned paper)

I would tend to believe PM2017 because later in the paper it says, "The bright optical counterpart, a V = 13.5 O5III(f) star, is
easily visible within the Head of the remnant." The star probably emits a lot of ionizing radiation and lights up, so-to-speak, the rest of the nebula. Note that SIMBAD lists the magnitude in the J band, which is infrared, so that makes sense.

Also the fact that Wikipedia uses SIMBAD as a source, so many test-makers will expect that value.
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### Re: Astronomy C

PM2017 wrote:
jonboyage wrote:
PM2017 wrote:
Correct me if I'm wrong, but simbad seems to give an apparent magnitude of 12.29.

this would imply an absolute magnitude of -6.20, using the distance modulus (with d= 50,000 pc, from the aforementioned paper)

I would tend to believe PM2017 because later in the paper it says, "The bright optical counterpart, a V = 13.5 O5III(f) star, is
easily visible within the Head of the remnant." The star probably emits a lot of ionizing radiation and lights up, so-to-speak, the rest of the nebula. Note that SIMBAD lists the magnitude in the J band, which is infrared, so that makes sense.

Also the fact that Wikipedia uses SIMBAD as a source, so many test-makers will expect that value.

Looks like I was completely wrong then xD

jonboyage and PM2017's stuff seems much more reasonable
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syo_astro
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### Re: Astronomy C

Welp, my internet was bad and post got deleted...so I'll try to summarize before internet goes out...

Adi: That sucks, happens to me too. Would be careful about the paper and other papers because it seems to focus a lot on the X-ray spectrum (and even calls the luminosity "Lx"). While paper reading can help, interpreting the results and data yourself can be a dangerous endeavor, tread carefully. I leave the rest to you all;).

Others: Not sure about that app. mag...no reference seems to be listed, but I guess maybe lots would be satisfied stopping there (though, if you want, feel free to dig deeper!...I won't right now). Question then: Do many test writers ask to give an app. mag. for a random DSO or to calculate the abs. mag for a random DSO (showing work or something)? It's a bit of an odd question, but I got my share of odd questions when I competed. I wouldn't be too surprised.

Fun fact: Alpha, me, someone from Troy I didn't get to see were at an astro conference! It's the American Astronomical Society / AAS conference, and we all presented our research:). Sadly, didn't take a look at many of the black holes / compact objects talks...that said, I should probably get test writing for everyone ASAP >.<.
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