Two competing models describe the evolutionary end-states of massive stars with initial pr… — ACT

Two competing models describe the evolutionary end-states of massive stars with initial progenitor masses between $20 M_{\odot}$ and $35 M_{\odot}$ ( $M_{\odot}$ represents the solar mass).

*Model 1*: Core collapse initiates a weak shock wave that fails to eject the majority of the outer stellar envelope. Roughly $90\%$ of the envelope's mass falls back onto the newborn core within hours. This process yields a faint supernova with a small amount of ejected mass ( $0.5$ to $2.0 M_{\odot}$ ) and a brief, low-luminosity electromagnetic transient.

*Model 2*: The iron core of the progenitor star is too massive to allow shock wave propagation. The star undergoes direct collapse, where the entire stellar mass falls directly into a black hole. No shock wave is generated, zero mass is ejected, and no electromagnetic emission is produced.

Astronomers recently observed three disappearing red supergiant stars in this mass range. The data collected from these observations are presented in the table below:

Star	Initial Progenitor Mass ( $M_{\odot}$ )	Detected Ejected Mass ( $M_{\odot}$ )	Observed Electromagnetic Emission
Star X	$24$	$0.0$	None
Star Y	$29$	$1.2$	Faint, brief transient
Star Z	$34$	$0.0$	None

Based on this information, which of the observed stars provide data that support Model 2 and contradict Model 1?

A
Star Y only
Star X and Star Z onlyCevap
C
Star X, Star Y, and Star Z
D
None of the stars

Cevap

Star X and Star Z only

The correct answer is the option identifying Star X and Star Z only. According to the table, both Star X and Star Z resulted in

0.0 M_{\odot}

of detected ejected mass and no observed electromagnetic emission. This directly supports Model 2, which states that stars undergoing direct collapse will eject zero mass and produce no electromagnetic emission. Conversely, Model 1 states that these stars will undergo fallback and eject

0.5

2.0 M_{\odot}

of mass while producing a brief, low-luminosity transient. The lack of ejecta and emission for Star X and Star Z thus directly contradicts Model 1.

Adım Adım Çözüm

Determine the criteria for supporting Model 2.

Model 2 predicts direct collapse, which means

0.0 M_{\odot}

of ejected mass and no ('None') observed electromagnetic emission.

This establishes the target parameters for the model we wish to support.

Determine the criteria for contradicting Model 1.

Model 1 predicts a faint supernova with ejected mass between

0.5

and

2.0 M_{\odot}

and a brief, low-luminosity electromagnetic transient. Therefore, observing

0.0 M_{\odot}

of ejected mass and no emission directly contradicts Model 1.

This establishes the target parameters for the model we wish to invalidate.

Evaluate each star from the table against these criteria.

Star X has

0.0 M_{\odot}

ejected mass and no emission, which matches Model 2 and contradicts Model 1. Star Y has

1.2 M_{\odot}

ejected mass and a faint transient, which matches Model 1 and contradicts Model 2. Star Z has

0.0 M_{\odot}

ejected mass and no emission, which matches Model 2 and contradicts Model 1.

This links the empirical data of each star to the theoretical models.

Anahtar Kavram

Evaluating new empirical observations to determine whether they support, contradict, or remain neutral toward competing scientific models.

Alternatif Yöntem

Construct a truth table comparing the output parameters (Ejected Mass, Emission) of the models to the observations. Model 1 requires [Ejected Mass > 0, Emission = Yes]; Model 2 requires [Ejected Mass = 0, Emission = No]. Matching the stars to these sets reveals Star X and Star Z fit Model 2, while Star Y fits Model 1.

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Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Alternatif Yöntem

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