gjdonatiello
SMSS J031300.36−670839.3
SMSS J031300.36−670839.3
The apparently anonymous magnitude 15.4 star at the center of this field, from DESI LS DR10, is UCAC4 115-002803 in Hydrus, otherwise known as SMSS J031300.36−670839.3.
Nothing special if it had not been identified as a peculiar star with low metallicity. Indeed, it is the one with the lowest metallicity known so far (Jinmi Yoon et al 2016 ApJ 833 20) with a [Fe/H] ratio <−7.8!
For comparison, in other low metallicity stars, this ratio is on average 3. For just about ten it is between 4 and 5.
This star is therefore very ancient and has an age of 13.6 billion years, that is, it lit up when the Universe was just 200 million years old.
Despite its very low metallicity, it does not belong to the elusive Population III, i.e. the very first stars that formed directly from primordial matter and are responsible for the cosmic dawn.
For those who want to know more:
iopscience.iop.org/art.../10.3847/0004-637X/833/1/20
The information and annotations in the image are of scientific utility because they identify the subject and place it in a specific moment. They also indicate the subject of interest. The absence of such information makes the images useless.
SMSS J031300.36−670839.3
SMSS J031300.36−670839.3
The apparently anonymous magnitude 15.4 star at the center of this field, from DESI LS DR10, is UCAC4 115-002803 in Hydrus, otherwise known as SMSS J031300.36−670839.3.
Nothing special if it had not been identified as a peculiar star with low metallicity. Indeed, it is the one with the lowest metallicity known so far (Jinmi Yoon et al 2016 ApJ 833 20) with a [Fe/H] ratio <−7.8!
For comparison, in other low metallicity stars, this ratio is on average 3. For just about ten it is between 4 and 5.
This star is therefore very ancient and has an age of 13.6 billion years, that is, it lit up when the Universe was just 200 million years old.
Despite its very low metallicity, it does not belong to the elusive Population III, i.e. the very first stars that formed directly from primordial matter and are responsible for the cosmic dawn.
For those who want to know more:
iopscience.iop.org/art.../10.3847/0004-637X/833/1/20
The information and annotations in the image are of scientific utility because they identify the subject and place it in a specific moment. They also indicate the subject of interest. The absence of such information makes the images useless.