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Trash star 11 EP

HD 142021

RA 239.2930° · Dec -69.2107° · star

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Score breakdown

· 3 badges
11 pts · Trash
Trash 15 pts → Common
  • Hot blue B-type star +6
  • Star +3
  • Main-sequence star +2
Total score 11

4 more points to reach Common.

Badges

  • Star · +3
  • Hot blue B-type star · +6
  • Main-sequence star · +2

Trivia

Hard to believe

  • True brightness. It pours out about 724.4 thousand times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads B9.5V — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
  • Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.

Find it in the sky

  • How to spot it. At magnitude 10.2 you'll want a small backyard telescope, over in Triangulum Australe.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around May — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out brilliant white (B−V 0.1) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

Properties

absmag
-9.82
bv
0.105
constellation
TrA
luminosity
737904.2301
mag
10.18
name
HD 142021
spect
B9.5V

Nearby objects

About HD 142021

HD 142021 is a trash star. It sits in the constellation TrA, shines at apparent magnitude 10.18 and has spectral type B9.5V.

Its spectrum reads B9.5V — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 142021 in the constellation TrA. At apparent magnitude 10.18, a small backyard telescope will bring it into view.

Like any astronomical target, HD 142021 is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why HD 142021 is a trash star

HD 142021 scores 11 points on Spacedle's rarity scale, which places it in the trash tier. Another 4 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, Hot blue B-type star and Main-sequence star — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.