An astronomer observed a distance quasar with a spectrometer. Aseries of absorpt

Question

An astronomer observed a distance quasar with a spectrometer. Aseries of absorption hydrogen lines can be resolved in thespectrum. She found all the lines shift by a factor 3 in wavelengthin comparison to the hydrogen lines measured in laboratory(i.e.->3)

(a) What is the redshift of the quasar?
(b) What is the receding velocity in unit of speed light relativeto us?
(c) In addition to the redshift, the astronomer also found thequasar's flux changes in a period of 9 days. What is the luminosityvariation period measured in the rest frame of the quasar?

Explanation / Answer

Quasars, Redshifts is a 1987book by Halton Arp, anastronomer famous forhis Atlas ofPeculiar Galaxies (1966) Arp argued that many quasarswith otherwise high redshift are somehowlinked to close objects such as nearby galaxies. Arp also arguedthat some galaxies showed unusual redshifts, and that redshiftsthemselves could be quantized.

These are controversial views which do not accord with thestandard model ofphysicalcosmology. It also contradicts the accepted model thatquasars are bright nucleiof very distant galaxies. Most astronomers reject Arp'sinterpretation of the data since the anomalous observations couldbe explained by perspective effects. Reportedly, some of Arp'scalculations seem to be simply "bad mathematics". Arp asserts thatmany questions he posed to the scientific establishment are stillunanswered and that his requests for more observation time havebeen systematically rejected.

Halton Arp's proposalwas an idea based on analyses done before the sky surveysincreased the number of measured redshifts by several orders ofmagnitude. The idea was that the cosmological redshift might beshowing evidence of periodicity which would be difficult to explainin a Hubble's Lawuniverse that had the feature of continuous expansion. However,most astronomers agree that the analysis suffers from poormethodology and small numberstatistics.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.