Module 5, Assignment 8
Post your spectral class and temperature for three of the stars, identified by the HD number, as well as the spectral type, B, and V from SIMBAD. Include a screen shot of at least one spectrum (send to Chris Martin) with the lines you have identified.Which technique do you think is more accurate for determining spectral class- temperature as determined by Wien’s Law or as determined by spectral lines?
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1) HD 331085
ReplyDeleteSpectral Class: 54 K5 V
Absorption lines:
5169.7nm (MgI) , 5891.2 nm(NAI), 5182.0nm (MgI), 4226.9nm (CaI), 4199.9nm, 4175.7nm (FeII), 4046.6nm(FeI), 4034.5nm(MnI)
Peak wavelength is 6071.8nm. Temperature calculated by using Wien`s law is 4760K
Simbad spectral class: K0
Flux: B: 10.47 V: 9.12
2) HD 331241:
Spectral class: 40 F8 V
Absorption lines: 4860nm (Hᵦ), 4338.3nm (Hᵧ), 6561.5nm (H ᾳ), 4102.4nm (Hᵟ), 3837nm(H9), 3934nm (CaII), 3968.8 nm (Hydogen ᵋ, CaII), 5169.9nm (MgI), 5890nm (NaI)
Peak wavelength: 4504.51nm. Temperature calculated by using Wien`s law is 6416K
Simbad Spectral class F5.
Flux: B: 11.30 V: 10.73
3) HD 331246
Spectral class: 14B3V
Absorption lines: 4860.3nm (Hydrogen ᵦ), 4470.5nm (He I), 4341.5nm (He II) , 4102.7nm (Hydrogen ᵟ) , 3970.9nm (Hydrogen ᵋ) , 3890.50nm (H8) , 3839.38nm (H9), 3800.4nm (?) , 3733.7nm (H11), 3754.2nm (H12), 3724.8nm (?).
Peak wavelength: 3915.0nm Temperature calculated by using Wien`s law is 7382K.
Simbad Spectral class: B3
Flux: B: 9.00 V: 9.00
1) HD 331085
ReplyDeleteAccording to absorption lines spectral Class: K5 V
Absorption lines:
5169.7nm (MgI) , 5891.2 nm(NAI), 5182.0nm (MgI), 4226.9nm (CaI), 4199.9nm, 4175.7nm (FeII), 4046.6nm(FeI), 4034.5nm(MnI)
It has a lot of metal absorption lines which is expected on cooler star. And there are not any Hydrogen Balmer series since it is not hot enough to energize Hydrogen. It is reasonable that metals are ionized easier.
Peak wavelength is 6071.8nm. Temperature calculated by using Wien`s law is 4760K
According to Wien`s law: K star
Simbad spectral class: K0
Flux: B: 10.47 V: 9.12
2) HD 331241:
According to absorption lines spectral Class: F8 V
Absorption lines: 4860nm (Hᵦ), 4338.3nm (Hᵧ), 6561.5nm (H ᾳ), 4102.4nm (Hᵟ), 3837nm (H9), 3934nm (CaII), 3968.8 nm (Hydogen ᵋ, CaII), 5169.9nm (MgI), 5890nm (NaI)
It has strong Ca II lines are stronger than the Hydogen Balmer series
Peak wavelength: 4504.51nm. Temperature calculated by using Wien`s law is 6416K
According to Wien`s law: F star
Simbad Spectral class F5.
Flux: B: 11.30 V: 10.73
3) HD 331246
According to absorption lines spectral class: B3V
Absorption lines: 4860.3nm (Hydrogen ᵦ), 4470.5nm (He I), 4341.5nm (H ᵧ) , 4102.7nm (Hydrogen ᵟ) , 3970.9nm (Hydrogen ᵋ) , 3890.50nm (H8) , 3839.38nm (H9), 3800.4nm (?) , 3733.7nm (H11), 3754.2nm (H12), 3724.8nm (?).
It has Helium absorption lines which are observed in hotter stars. It has also strong Hydrogen Balmer series since they can energize Hydrogen without ionizing Hydrogen.
Peak wavelength: 3915.0nm Temperature calculated by using Wien`s law is 7382K.
According to Wien`s Law: Spectral class is A star.
Simbad Spectral class: B3
Flux: B: 9.00 V: 9.00
In analysis of HD 331246 it is obvious that using absorption lines are more accurate in identifying which class stars belong to. According to Wien`s law HD 331246 is classified as A star. However, in A stars we do not observe Helium absorption lines, A stars are not hot enough to energize Helium. It does not have any ionized Helium absorption line so it is not an O star. That is why it makes sense for HD 331246, it is a B star but closer to O star class.
In my first post, I labeled 4341.5nm absorption line as He II (4339nm), however after reviewing tutorial I saw that B stars are not hot enough to ionize Helium. I checked absorption lines one more time and saw that it is H ᵧ absorption line which is observed at 4340nm.
This website will help you; http://casswww.ucsd.edu/archive/public/tutorial/Stars.html
ReplyDeleteHere are the results for assignment 8. My group was 2.
ReplyDeleteHD331066
Wein's Temperature 7361 K, star class A
Spectral analysis star class A
Database star class B8
B 9.58
V 9.59
HD331078
Wein's temperature 7186 K, star class A
Spectral analysis star class F
Database star class A7
B 10.39
V 10.05
HD331083
Wein's temperature 6412 K, star class F
Spectral analysis star class F
Database star class G5
B 10.00
V not posted
Images emailed to Chris contain my analysis of the spectra.
The spectra method for determining star class is more reliable because conditions on the surface of the star cause absorption. In hot stars, the absorption is minimal but in cool stars this can result in underestimation of star temperature using Wein's law. However, the spectra method is more difficult to use. An experienced person could probably do a better job identifying the star class than I was able to do.
ReplyDeleteI want to comment on Fatima's reply to the last question in this module. This question is really just to get you thinking. There are a lot of factors that you can't be expected to have picked up already, so there is no "right" answer here! But I should comment that absorption in hot star atmospheres is just as great as in cooler stars: hot stars have completely ionized all the elements so there are no possible lines. It's a case where the absence of evidence (lines of Ca, or Fe for example) is not the evidence of absence! Those elements are certainly present, but only as bare nuclei with no electrons to make line transitions.
ReplyDeleteFrom SIMBAD query
ReplyDeleteHD331057- A0 (B=9.20 V=9.20)
HD331059- K5 (B=10.82 V=9.73)
HD331061- A5 (B=11.2 V=10.9)
Using Wien's law I got the following temperatures in 2 SF:
HD331057 - 3924 angstrom- 7385 K (7400K)
HD331059 - 6527 angstrom - 4440K (4400K)
HD331061 - 4021 angstrom - 7207 K (7200K)
Star HD 331057 is classified as Class A. It has the following prominent absorption lines (3753, 3772, 3799, 3836, 3892, 3970, 4102, 4340, 4860, 6558, 6873, 7189. This star has a strong Hydrogen Balmer Series at 4102, 4340, 4860 and 6558 and Ca+, Mg+, Fe+. From Jacobi, this star is class A star.
HD 331059 is classified as class K. It has the following absorption lines: 4302, 4385, 4529, 4863, 5172, 5270, 5328, 5406, 5591, 5708, 5891, 6259, 6496, 6564, 6873 and 7188. It has a prominent lines at 4302 (Magnesium), 5172 (Iron II), 5891 (Sodium) and 6873 (Oxygen) . There is a weak Balmer Series, Ca and Mg.
HD 331061 is a Class A star with a prominent lines at 3836, 3892, 3936, 3970, 4102, 4341, 4862, 5890, 6563, 6870, 7187. I t has a strong H-alpha at 6563, H-beta at 4861and H- lambda at 4340. H-sigma at 4101 and H-epsilon at 3970; all strong. It has also a weak CaII at 3933 and 3968.
I think Wien’s law can be used to compute for the temperature and the absorption data can be used to classify star.
Group 3:
ReplyDeleteHD 331241 I have calculated the temperature of this star to be 6400 K measured at its peak wavelength of 4506 A. In addition, I have identified many of the hydrogen lines with CaII, NIII, and Mg I lines that would constitute “many ionized metals”. For these reasons, I will classify this star as in the F class. B= 11.30 V= 10.73 Class F5 D
HD 331246 I have calculated the temperature of this star to be 7200 K using Wien’s equation based upon the measurement of its peak wavelength of 4024 A. It seems to be strong in many of the hydrogen lines ( H8, H9, H beta, H alpha, with CaII and NIII, ( but no Mg I ) lines that would constitute “not so many ionized metals”. For these reasons, I will classify this star as in the A class.
B= 9.0 V= 9.0 Class B3V D
HD 332087 I have calculated the temperature of this star to be 7400 K using Wien’s equation based upon the measurement of its peak wavelength of 3912 A. It seems to be strong in many of the hydrogen lines ( H8, H9, H 10, H 11 and H 12 , with CaII and NIII, ( but no Mg I ) lines that would constitute “not so many ionized metals”. For these reasons, I will classify this star as in the A class.
B= 9.53 V= 9.18 Class FO D
Apparently, my resources (http://casswww.ucsd.edu/archive/public/tutorial/Stars.html???) were not as precise as the SIMBAD sites resources. I did not have grasp the concept of the sub categories of each class, nor of the specific distinctions between the kinds of hydrogen lines visible (alpha, beta, gamma vs. H8, H9, H10 etc.). I was thinking that it would be especially easy and more precise by just matching spectral lines to known classes,etc and that once the patterns were recognized it would be pretty quick classifying the stars (but looking at the files on the above website did not confirm this idea). As a result, I don’t think the using Wien’s calculation alone is adequate.
HD 331085 T = 4800K, Class K (SIMBAD Class K B 10.47 V 9.12)
ReplyDeleteHD 331246 T = 7400K, Class A (SIMBAD Class B 9.00 V 9.00)
HD 332087 T = 7200K, Class A (SIMBAD F Class B 9.53 V 9.18) HUH????
HD331241 T = 6500K, Class F (SIMBAD = F Class, B 11.30 V 10.73)
I don't think my methodology was very accurate at all! I default to SIMBAD, but hated trying to understand the data on their site. I used the temperature more than the other data when identifying the class - but the absorption lines were nice validation or deciding factor when I was undecided.
Justification for my choice on the classes... I used the temperature calculated from Weins Law first, then used the absorption lines as verification or to make the final decision.
ReplyDeleteHD 331085 T = 4800K, Class K because of temperature and the fact that it had some of the metals.
HD 331246 T = 7400K, Class A because of the strong absorption in the hydrogen (Balmer) elements.
HD 332087 T = 7200K, Class A also because of all of the hydrogen (Balmer) elements, although this was drastically different from what I found on SIMBAD.
HD331241 T = 6500K, Class F mostly because of temperature and the smaller amount of hydrogen.
From http://simbad.harvard.edu/sim-fid.pl
ReplyDeleteHD332087- F0 (B=9.53 V=9.18)
HD331085- K0 (B=10.47 V=9.12)
HD331241- F5 (B=11.30 V=10.73)
Using Wien's law (2 SF):
HD332087 -7200K
HD331085 -4800K
HD331241 -6400K
HD332087 has the following prominent lines: Telluric, Ha, NaI, H-beta, H-gamma, H-delta, CaII, H8 and H9. It has a weak ionized Ca+ and medium Balmer series.
The star's temperature from Wien's law is between class F and A. But it is peak and temperature suggest that it should be in Class F. Jacobi confirm that this star is F0 star
HD331085 has the following prominent lines: Telluric NaI. MgI and H-alpha. This star has a weak Balmer series. Jacobi states that this star is K0.
HD331241 has the following prominent lines: Telluric, H alpha, NaI, MgI, Hbeta, Hgamma, TiII, Hdelta, CaII, Halpha. This star has a medium Balmer series. It also contains metals and Hydrogen. From Wien's law, this star is class F and Jacobi confirms that this star is really class F (F5 star)
Using the peak wavelength from the graphical analysis and wien's law, we can compute for the temperature of the stars. The absorption lines will gives us the idea on the classification of the stars
HD 331054 (peak at 535.7 nm)
ReplyDeleteT=5400K
B=9.85
V=8.91
Type K0
HD 331055 peak at 450.7 nm
T=6400K
B=10.97
V=10.39
Type F8
HD 331057 peak at 392.4 nm
T=7400K
B=9.2
V=9.2
Type A0
Star HD331054: Using the highest peak I got 5410K which suggests a class G star. The spectral lines and the prominent lines are Ca+(strongest), neutral metals strong, H(weak) . Comparing the spectrum to the Jacobi. The star is classified as K not G
Star HD331055: From the higest peak, I derived a tempertaure of 6430K. This temperature suggests a F star. This star has a prominent lines of (H(weaker), Ca+ and ionized metals. From Jacobi atlas. HD331055 is a class F star.
Star HD331057: Using the highest peak I got a temperature of 7390K which suggests a class F star. The prominent spectral lines has strong H, Ca+, Mg+, Fe+. Comparing this star to Jacobi atlas, HD331057 is a class A star.
Wien's law will give us the temperature and absortion analysis will give us the star's class or type.
HD 331078
ReplyDeleteWhen comparing to the jacoby atlas, this appears to be an A star
Absorption Lines present at 3834, 3890, 3934, 3970, 4102, 4338, 4863, 6566, and 6871
Peak Wavelength: 4019 A or 4.02x10^-7 meters
Temperature=(2.89x10^-3Km)/( 4.02x10^-7 m) = 7190 K
This temperature correlates with a Class A star
From the Simbad site, this star is an F2 star, with a B value of 10.49 and V value of 10.05.
HD 331081
When comparing to the jacoby atlas, this appears to be an M star
Absorption Lines present at 4772, 4963, 5177, 5455, 5903, 6240, 6719, 7136
Peak Wavelength: 7522 A or 7.52x10^-7
Temperature=(2.89x10^-3Km)/( 7.52x10^-7 m) = 3840 K
This temperature correlates with a Class M star
From the Simbad site, this star is an M1 star, with a B value of 11.5 and V value of 9.81
HD 331083
When comparing to the jacoby atlas, this appears to be an F star
Absorption Lines present at 3829, 3936, 3968, 4102, 4305, 4341, 4860, 5170, 5265, 5891, 6561, 6871, and 7188
Peak Wavelength: 4507 or 4.51x10^-7
Temperature=(2.89x10^-3Km)/(4.51x10^-7 m) = 6410 K
This temperature correlates with a Class F star
From the Simbad site, this star is a G5 star with a B value of 10 and no V value published that I saw
On a few of mine, the Wien’s law and spectral analysis methods for star classification agreed. I think they both have their value. I think the classification system is a more of a general guideline, but there can be stars that don’t perfectly fit a predetermined classification scheme. I remember reading that a Class A9 star is closer to a G0 than it is to an A0. This suggests to me that there can be some uncertainty or slight disagreement between the two methods, which is OK.
Group 3
ReplyDeleteHD 331085
peak λ- 607nm
Temperature= 4800K
HD 331241
peak λ-427 nm
Temperature=6800K
HD 331246
peak λ- 391nm
Temperature= -7400K
From Jacobi and GA:
HD 331085:
K0 , B= 10.47, V=9.12
prominent spectral lines - Ti, MgI, Na I, N IV, and Telluric Bands
HD 331241:
F5, B=11.3, V=10.73
prominent spectral lines -- Ca II, Hβ, Na I,and Hα
HD 331246:
B3V, B=9.0, V=9.0
Prominent spectral lines - H8, Fe II, Hγ, Hβ, and Hα
Wien's law only give us an estimated temperature for each star. Sometimes there are some peaks that are outside the continuum so we cannot use Wien's law to calculate the temperature. The effective temperature of the star and spectral type can be determined accurately using spectral lines. The variations in spectral lines for different stars are due primarily to the difference in temperature of the outer layers of gas in the star.
From SIMBAD:
ReplyDeleteHD331055 – F8 (B=10.97 V=10.39)
HD331057- A0 (B=9.20 V=9.20)
HD331059- K5 (B=10.82 V=9.73)
Using Wien’s law, the temperature is
HD331055 – 451nm – 6400K
HD331057- 392 nm- 7400K
HD331059- 607 nm- 4800K
HD331055 – This star has the following prominent absorption lines: Halpha, CaII, MgI, H beta, H gamma, TiII, H delta, This star has a weaker H and ionized metals. The temperature suggests that this star is F star. Jacobi confirms that this star is really a class F star.
HD331057 has the following prominent absorption lines; Telluric, H delta, H gamma, H beta, H alpha and NaI. The temperature suggests that this star is under F star. This star is classified as class A since it has strong hydrogen and ionized metals. Jacobi confirms this classification
HD331059 has the following prominent absorption lines: Telluric, BaII, CaII , MgI, NaI. This star is classified as class K, it has weak hydrogen and neutral metals. The temperature from Wien’s law suggests that this star is K star. Jacobi confirms that this star is really a K star.
Wien's Law can be used to estimate the temperature of the star and spectral line analysis will give us the type of the star.
From the peak wavelength of each star, I computed for the temperature. And I obtained the following information from SIMBAD
ReplyDeleteHD331085-610nm (4900K) K0 (B=10.47 V=9.12)
HD331241-450nm (6700K) F5 (B=11.30 V=10.73)
HD331246-390nm (7700K) B3V(B= 9.00 B=9.00)
HD331085: Telluric Na I. Mg I and H alpha
It has weak Balmer series. It has some metals metals. From Jacobi atlas, this star is K star
HD331241: Prominent lines: Telluric, H alpha, NaI, MgI, Hbeta, Hgamma, TiII, Hdelta, CaII, Halpha. Both Wien's law and jacobi atlas suggest that this star is a F star.
HD331246: Prominent lines: For HD331246, the absorption lines in angstroms are:Telluric
H-alpha, NaI,H-beta,MgII,HeII,H-delta,H-epsilon
H8, H9. This star is A star based from the temperature computed. Spectral lines suggest that this star is B star. Jacobi confirms that this star is a B star not a A Star
HD331085 - 4800K peak 600 nm
ReplyDeleteHD331241 - 6400K peak at 450 nm
HD331246 - 7400K peak at 390 nm
From Simbad:
HD331085 – B= 10.47 and V=9.12 - K0 star
HD331241 – B=11.30 and V=10.73 - F5 star
HD331246 – B=9.00 and V=9.00 - B3V star
For HD331085, the following are the prominent absorption lines: Telluric (6871), H-alpha(6559), NaI (5891), Fe (5269) MgI(5170) . This absorption lines suggest that this star is K star.
For HD331241, the following are the absorption lines: Telluric (6871), H-alpha(6561), NaI(5894), Fe(5267), MgI (5172), Hbeta(4863),H-gamma(4339), TiII(4307), H-delta(4102), CaII(3971), H-alpha (3837)
A class F star has prominent lines of Hydrogen, ionized calcium, iron and these lines show that this star is F star.
For HD331246, the absorption lines: Telluric (7190) Telluric (6871) H-alpha (6561) NaI (5896) Hbeta (4863) MgII (4473) HeII (4339) Hdelta (4103) H-epsilon (3973) H8 (3890) H9 (3837) H10 (3800). This star has a medium hydrogen series and neutral He absorption. This star is a B star.
Absorption lines will give the classification of the star and Wien’s law can be used to estimate the surface temperature of the star