Deep-Sky Tour

Dig deep into Virgo for this gamut of gal­ax­ies, all within Markar­ian’s Chain

Sky at Night Magazine - - CONTENTS -

Tick the box when you’ve seen each one

1 M84 This month’s tar­gets all be­long to Markar­ian’s Chain, a 1.3º curv­ing line of gal­ax­ies in the Bowl of Virgo. Lo­cate it mid­way be­tween mag. +2.1 Denebola (Beta (`) Leo­nis) and mag. +2.8 Vin­demi­a­trix (Ep­silon (¡) Vir­gi­nis) both of which are shown on our All-Sky Chart. The chain starts with mag. +10.1 M84, a face-on lentic­u­lar gal­axy 60 mil­lion lightyears away. A 6-inch scope shows it as a hazy, 2.5x2ar­cminute patch that bright­ens to­wards a star­like point at its core. Larger in­stru­ments show the core as ex­tended rather than stel­lar, but re­veal lit­tle else. For a long time M84 was in­cor­rectly clas­si­fied as an ‘E1’ type el­lip­ti­cal, be­cause be­ing face on it is hard to dis­tin­guish from that class of gal­axy. 2 M86 Due to the rel­a­tively small size of Markar­ian’s Chain, lo­cat­ing other mem­bers is easy. Our next stop, M86, sits 17 ar­cmin­utes east of M84. Here the el­lip­ti­cal/lentic­u­lar con­fu­sion con­tin­ues: M86 is listed var­i­ously as an E3 el­lip­ti­cal or an S0 lentic­u­lar, though mod­ern clas­si­fi­ca­tions favour the lat­ter. It’s frac­tion­ally brighter than M84 at mag. +9.9, and ap­pears larger and more elon­gated. That said its over­all guise isn’t dis­sim­i­lar to M84, with a 6-inch scope re­veal­ing lit­tle more than a hazy halo bright­en­ing to a star-like point. Through a small scope M86 ap­pears to be 2x1.5 ar­cmin­utes in size, but this in­creases with aper­ture. A 12-inch scope re­veals it as a 3x5-ar­cminute haze. 3 NGC 4388 Many of the mem­bers of the Virgo Gal­axy Clus­ter are el­lip­ti­cals, but NGC 4388 is a no­table ex­cep­tion. It forms an ap­prox­i­mate equi­lat­eral triangle with M84 and M86, NGC 4388 mark­ing the triangle’s south­ern point. At mag. +11.0, it’s dim­mer and harder to see than the two pre­vi­ous gal­ax­ies, but re­ally stands out be­cause of its lovely shape. It is an edge-on spi­ral gal­axy with a bright ac­tive nu­cleus. Through a 6-inch scope the gal­axy looks like a nee­dle of light, 3x0.5 ar­cmin­utes in size, the core re­gion caus­ing a slight bulge. The arms present a mot­tled ap­pear­ance through an 8-inch or larger scope, which will also show the core off­set to the west of cen­tre. 4 NGC 4438 & 4435 Up next is a gal­axy pair, NGC 4438 and 4435, which can be found 22 ar­cmin­utes east of M86. To­gether these are known as ‘Markar­ian’s

Eyes’ or sim­ply ‘The Eyes’. NGC 4438 is the brighter of the two at mag. +11.0, NGC 4435 be­ing +11.7. There is un­cer­tainty as to what is pre­cisely hap­pen­ing be­tween the two gal­ax­ies (and pos­si­bly M86), but it ap­pears that NGC 4438 is a spi­ral gal­axy grav­i­ta­tion­ally af­fected by an in­ter­ac­tion with NGC 4435. The pair is sep­a­rated by 4.3 ar­cmin­utes. A 6-inch scope shows NGC 4435 as a small, 1-ar­cminute haze and NGC 4438 as a larger 3x1 ar­cmin­utes. Averted vi­sion re­ally helps with the lat­ter, as NGC 4438’s larger size low­ers its sur­face bright­ness. 5 NGC 4473 We pass mag. +13.0 NGC 4458 and mag. +12.1 NGC 4461 to reach tar­get five, NGC 4473; it is 40 ar­cmin­utes north­east of NGC 4438. Here, we’ve just slipped over the bor­der from Virgo into Coma Berenices. An 8-inch scope shows an elon­gated haze mea­sur­ing 1.5x1 ar­cmin­utes, with a bright core that ap­pears to have been stretched east-west for a dis­tance of 3-4 arc­sec­onds. This is an el­lip­ti­cal gal­axy, which un­usu­ally ap­pears to have been flat­tened into a more disc-like struc­ture. This sug­gests that it may have been the re­sult of a merger be­tween sev­eral galac­tic nu­clei. Don’t be afraid to pile the mag­ni­fi­ca­tion on here to re­veal the elon­gated core. 6 NGC 4477 & 4459 The penul­ti­mate marker of the chain is NGC 4477, a mag. +11.4 barred-lentic­u­lar gal­axy that lies 12 ar­cmin­utes to the north and slightly west of NGC 4473. NGC 4477 is sim­i­lar to but ap­pears more ob­vi­ous than 4473. It’s rea­son­ably bright and ap­pears larger than 4473. Its core is bright with a mot­tled sur­round­ing halo when seen with larger in­stru­ments. The chain ends with the mag. +11.3 lentic­u­lar gal­axy, NGC 4459 ly­ing 25 ar­cmin­utes north­north­east of NGC 4477. This gal­axy is rel­a­tively small and con­cen­trated, ap­pear­ing 1.1 ar­cmin­utes across through an 8-inch scope. A mag. +8.7 star, HIP 60918, ap­pears to touch the edge of the gal­axy and acts as a use­ful marker to show you are look­ing at the right ob­ject.

NGC 4438 (bot­tom) and NGC 4435; it’s thought that th­ese gal­ax­ies are in­ter­act­ing with one an­other

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