For a detailed description of constellations, lunar-mansions and stars in galaxy Milky Way, see this article.
Thus 'Dhruva' clearly is Polaris. The saptha Rishi's are the seven major stars of Ursa major. We can easily identify from figure 19, that 'Marichi' stands for Alkaid, 'Vasishta' stands for Mizar, 'Angirasa' stands for Alioth, 'Athri' stands for Megrez, 'Pulasthya' stands for Phecda, 'Pulaaha' stands for' Merak and 'Krathu' stands for DuBhe. The companion star for Mizar is Alcor. Hence 'Arundhathi' stands for Alcor. In figure 19, Vasishta and Arudhathi (Mizar-Alcor) can not be seen separate.
Canto 5, Chapter 23
Description of the Stars of S'is'umâra, our Coiling Galaxy: Here Vishnu is seen in coiled galaxy form and this article establishes that Polaris star was known as Dhruva to indians because it was pretty much "fixed" relative to other stars.
(1) S'rî S'uka said: '1.3 Million yojanas above them [the stars of the sages] one finds that supreme abode of Lord Vishnu which is praised in the mantras of the Rig Veda. It is the source of life of all entities that live from this moment till the end of creation. There the great devotee Dhruva, the son of Uttânapâda resides even today. His glory of obedient devotion I've described already. Agni, the fire god, Indra the king of heaven, the founding father who is the Prajâpati, Kas'yapa as also Dharmarâja, in unison full of respect move around that place keeping it to their right [see 4.9]. (2) For all the restless luminaries such as the planets and the stars that place constitutes the incandescent radiating pivot that is established by the Lord. The inconceivable, all-powerful force of Time is considered the cause of their revolving. (3) The luminaries keep their positions, just like three bulls that for threshing rice are yoked to a central pole [at fixed distances]. Moving in their orbits they have a fixed position relative to the inner and outer rims of the wheel of time, the same way as the planets around the sun keep their positions. Holding on to Dhruvaloka till the end of creation, they revolve in the sky as if they're driven by the wind, just like heavy clouds and big birds do who controlled by the air move their bodies around in respect of their previous positions. Thus the luminaries behave consequently, by the combined effort of material nature and the Original Person, the way they always have and never collide with the earth.
(4) Some imagine this great army of luminaries to be a s'is'umâra [a dolphin] and describe it, concentrated in yoga, as [that what can be seen of] the Supreme Lord Vâsudeva [see also a picture of the celestial sky as factually seen in a telescope]. (5) With its tail pointing to the end of the row of fixed stars in the sky [dhruva] and with its head bent downwards, it has its body coiled. The [planets of] Prajâpati, Agni, Indra and Dharma are found on the tail with [those of the demigods] Dhâtâ and Vidhâtâ at its base. The seven sages are situated on its hip. With its body coiling to the right there are as its separate body parts at its northern side the constellations of the fourteen stars [from Abhijit to Punarvasu] that mark the northern course [of the sun] and to the south there are the same number of them [from Pushyâ to Uttarâshâdhâ] marking the southern course. Together the both sides appear like the coiled body of a dolphin. On its back one sees the stars called Ajavîthî [*] and on the belly one sees the 'celestial Ganges' [the series of stars along the full body of the S'is'umâra we know as our Milky Way]. (6) Punarvasu and Pushyâ constitute the loins right and left. Ârdrâ and As'leshâ as well to the right and left are his flippers. Abhijit and Uttarâshâdhâ are the left and right nostril with following next in due order S'ravanâ and Pûrvâshâdhâ for its eyes left and right. Dhanishthhâ and Mûlâ are the right and left ear and the eight stars such as Maghâ marking the southern course are to be seen as the left ribs while the same number of stars like Mrigas'îrshâ that mark the northern course are there as the ribs positioned at the other side to the right. S'atabhishâ and Jyeshthhâ should be seen as the position of the right and left shoulder. (7) On its upper chin there is Agasti [Agastya] and on its lower one there is Yamarâja. As its mouth there is Mars, as its genitals there is Saturn, Jupiter is found at the back of the neck, the sun is found at the chest. In its heart Lord Nârâyana is found while the moon serves as its mind. As the navel there is Venus, the two sides of the breast is where the As'vins reside, Mercury is there as the in- and outward going breath, Râhu is the neck and the comets are found all over its body with the numerous stars as its pores.
(8) This [form of S'is'umâra] certainly is the form of the Supreme Lord, of Lord Vishnu who consists of all the demigods. With that form before one's eyes one should each morning, noon and evening in all modesty meditate upon the following words: 'Our obeisances unto this resting place of all the luminous worlds, unto the master of the demigods, the Supreme Personality in the form of Time upon whom we meditate' [namo jyotih-lokâya kâlâyanâya animishâm pataye mahâ-purushâya abhidhîmahîti, see also 2.2: 24]. (9) Those who in respect of that leader of the demigods consisting of all the planets and stars, that destroyer of sin, practice the mantra as mentioned above by three times a day offering their respects this way or by three times a day meditating as such [in silence], will by that respect [for our sweet Lord in the form of] time very soon find all their sins annihilated.'
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