Questions tagged [observational-astronomy]

Questions about the techniques and practice of observing the night sky.

Filter by
Sorted by
Tagged with
0
votes
0answers
1 view

What portion of all exo-planets can't be observed?

Exo-planets are usually observed by small decreases of the outgoing power of the stars accompanying them, when the planet passes between us and the star. The orbits of the exo-planets lay in one plane....
3
votes
0answers
43 views

Infall velocity in core-collapse supernovae

In this article Neutrino Transport in core-collapse supernovae, in the description of core-collapse supernova mechanism, it is stated that The velocity of infalling matter in the core increases as we ...
0
votes
0answers
18 views

How exactly will Trailblazer (the precursor to SatHub) help Astronomers plan their optical observations? Will it be open to the public?

Space News' Astronomers back technical efforts to reduce impacts of satellite megaconstellations while seeking regulatory solutions says: At the conclusion of the weeklong SATCON2 workshop July 16, ...
2
votes
0answers
19 views

How the data collected during 5 year DESI operation will be analyzed with regards to finding what dark energy really is?

Dark Energy Spectroscopic Instrument, or DESI at the end of it's 5 years operation will create the largest 3-D spectroscopic map of the universe. How the data collected during 5 year DESI operation ...
5
votes
1answer
196 views

Is there molecular hydrogen in the Sun's atmosphere? If so, how much, and how was that first determined and measured?

I don't have a license to practice chemistry, but I'll convert Wikipedia's bond dissociation energy of 435.7 kJ/mol to eV by dividing it by $C / N_A$ where $C$ is 1 Coulomb and $N_A$ is Avogadro's ...
1
vote
1answer
74 views

What is the distance between solar system and a distant galaxy

When we say a galaxy is 300 million light-years away, is that its distance now or 300 million years ago?
1
vote
1answer
42 views

Vacuum and air wavelengths in spectroscopy

In the SDSS page https://classic.sdss.org/dr7/products/spectra/vacwavelength.html, it is written Because the SDSS observes many quasars at rest-frame ultraviolet wavelengths, the data are stored in ...
1
vote
1answer
44 views

How to determine the color term for a filter with a systematically bluer offset than the standard

This is a hypothetical scenario in an attempt to test my understanding of the color term when performing photometric calibrations: Imagine we are observing stars through a B filter with an offset ...
1
vote
0answers
26 views

What are Euclidean-normalized differential source counts?

I would like to know what the Euclidean-normalized and differential source counts mean in "Euclidean-normalized differential source counts". It would be great to hear a) a clear definition ...
6
votes
1answer
506 views

Conventional units for astronomical object coordinates

I would like to know what the conventional units for identifying a celestial object (J2000.0) are. For instance, I am reading a paper in which they refer to object SDSSJ170013.70+400855.6; I am ...
2
votes
3answers
1k views

If a black hole was headed for our solar system and would arrive within a year, would we necessarily know of it?

Basically, is our observational technology and coverage sufficient enough to pretty much always spot incoming objects like a black hole when they're a year from arriving? If so, within what time frame ...
2
votes
1answer
73 views

Is it known in the scientific community that dark matter does not interact with light?

Does dark matter not interact with light, or does it not interact with anything in the universe? What do they talk about in the scientific community the most?
5
votes
3answers
1k views

Would we have spotted the ascent stage of Apollo 11's Eagle if it was still in orbit around the Moon?

This video: Is Apollo 11's Lunar Module Still In Orbit Around The Moon 52 Years Later? claims, based on orbital simulations, that there is a chanche that the lunar module of Apollo 11 might be still ...
4
votes
1answer
91 views

Would people on opposite sides of the earth see different details of the moon, if so are there actual photos demonstrating this?

I am aware of phases and the fact that opposite sides will see the moon flipped relative to the other but what I’m asking specifically is would the almost 8000 mile difference between the two ...
4
votes
0answers
65 views

A new (radio) neutrino telescope in Greenland?

I just stumbled upon ScienceMag news from July 14th, 2021 which says: By placing hundreds of radio antennas on the ice surface and dozens of meters below it, they hope to trap elusive particles known ...
4
votes
3answers
88 views

Do telescope measurements (in meters, usually) measure in a straight line, from edge to edge, or follow the curve of the mirror?

Somehow, no site or book or magazine has clarified this question for me.... Perhaps I am an idiot, but, Is the parabolic primary mirror on the new James Webb Space Telescope (JWST) 6.5 meters from ...
5
votes
1answer
59 views

If the visibility function is the Fourier transform of the sky brightness distribution, why do you need the dirty beam and dirty image to find it?

In radio astronomy, the dirty image is equal to the inverse Fourier transform of the uv-plane coverage times the sampled visibilities. The dirty image is also equal to the convolution of the "...
5
votes
1answer
85 views

From Proxima b, could any planets around Sol be imaged directly by a strong telescope? If so, which ones would be easiest to spot?

How strong would a telescope (and what kind of telescope) on Proxima Centauri b have to magnify to discern any planets around Sol, and which planets would be easiest to spot? One might think the ...
2
votes
1answer
42 views

In radio astronomy, why do shorter baselines trade angular resolution for surface brightness?

I'm reading about radio astronomy and array configurations on the Very Large Array's (VLA) website. They state that the longest baselines provide the best angular resolution, but have very limited ...
4
votes
1answer
78 views

Is there a complete guide on how to use telescopes?

tl;dr As said by @uhoh in the comments, is there A Big Book of Telescopes? i.e: Is there some kind of media that gives a complete treatment to telescopes? I am relatively new to Astronomy.SE. I wanted ...
5
votes
2answers
721 views

What can I see with different apertures?

I'm looking to buy a telescope, and every mainstream website says that aperture is the most important factor, and buy the largest telescope your budget can afford. However, a website I found offering ...
1
vote
1answer
45 views

How much real time was compressed into this 10 second long timelapse Hubble video of Jupiter's aurora?

The HubbleESA video Timelapse of Jupiter’s auroras is discussed in the ESAHubble page Timelapse of Jupiter’s auroras and includes the identifier heic1613a. However ...
2
votes
0answers
33 views

Why does X-shooter use double passes through prisms for Echelle cross-dispersion instead of gratings?

The catchy title Down-the-barrel observations of a multiphase quasar outflow at high redshift: VLT/X-shooter spectroscopy of the proximate molecular absorber at z=2.631 towards SDSS J001514+184212 ...
2
votes
2answers
376 views

What exactly is the orbital period value of Sirius binary star system?

My Textbook An Introduction to Modern Astrophysics 2nd edition (2017), page 557 mentions that the modern value is 49.9 years. But Wikipedia mentions 50.1284±0.0043 years. Which is correct? Or, has the ...
2
votes
0answers
29 views

Could we detect a globular cluster consisting entirely of black holes?

A paper recently came out in Nature simulating the evolution of the $\sim10^4M_{\odot}$ globular cluster Palomar 4 (Gieles et al. 2021, arXiv link). The authors argue that in ~1 billion years, a ...
3
votes
0answers
36 views

Estimate the shape of an object based on flux curve

Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
4
votes
1answer
75 views

How to extract galaxy spectra for different radii in Python for spectra taken by long slit spectrograph?

I am trying to extract the kinematics from the elliptical galaxy NGC 4697 using the Fourier Correlation Quotient (FCQ) algorithm described by Bender (http://adsabs.harvard.edu/full/1990A%26A...229.....
4
votes
0answers
63 views

What about the U planet?

In 2014 and 15, an object called U has been detected by the ALMA in Chile, considered likely to be a super-Earth at 300 AU, among other options. Is it located where the hypothetical super-Earth ...
1
vote
0answers
29 views

How does speckle imaging fit in to 21st century high resolution imaging from ground based observatories?

Phys.org's Astronomers uncover evidence that there could be many more Earth-sized planets than previously thought references Speckle Observations of TESS Exoplanet Host Stars. II. Stellar Companions ...
1
vote
2answers
453 views

Could more objects from the Oort cloud with highly elliptical orbits be discovered in the future?

It took the modern astronomy to live to the year of 2014 to discover 2014 UN2711 (sized roughly 100-200 km and now being re-qualified from a comet to mini object), which has "extremely" ...
0
votes
0answers
31 views

.fits Files for Exoplanets

I am learning to use AstroImageJ software. And using this software to plot transit graph for Exoplanet orbiting the star. I want to know from where can we find the .fits file of target star ? I tried ...
1
vote
0answers
16 views

Reference request: how optical correlators combine light from multiple telescopes to produce ultra-high resolution interferometric images?

This is a reference or resource-request because it may be too challenging to explain in an answer post, but if you'd like to attempt a short summary as well, that will be great! I have a basic ...
1
vote
1answer
49 views

What is the most grazing exoplanet transit that has been reported with high confidence?

The abstract of Past, present and future stars that can see Earth as a transiting exoplanet reads: In the search for life in the cosmos, transiting exoplanets are currently our best targets. With ...
0
votes
1answer
61 views

What are the most distant extended objects we can see (or that are seen up till now)?

Apart from stars and galaxies, what are the most distant extended objects that we have ever seen? For example, can gas clouds or nebulae be seen in other galaxies? In the list referred to in the link ...
0
votes
2answers
65 views

Setting of stars [duplicate]

In the book Thinking Physics by Lewis Caroll I came accross the following exercise: Using a good digital watch, get the exact time when a bright star goes behind a distant building or tower. A day ...
1
vote
0answers
26 views

Do point spread functions from large single telescopes using adaptive optics still look like Airy functions for narrow-band filters?

this answer to Claim that 30-m class telescopes will have resolution far superior to Hubble: true? mentions ...the possibility of attaining near diffraction-limited images using adaptive optics. The ...
2
votes
1answer
85 views

Details about the next big comet 2014 UN271?

The announcent of the massive trans-Neptunian object 2014 UN271 to be a comet is rather new (June 22nd, 2021) and really exciting. That comet is rather huge (~100km diameter) and "falling toward ...
4
votes
0answers
52 views

What capabilities of Hubble are unique and irreplaceable? What can it do that simply can't be done by any other ground or space-based telescope?

It's impossible to summarize in an SE post the depth and breadth of the contributions to science made using the Hubble Space Telescope. Above the atmosphere it has access to an extremely dark and ...
2
votes
2answers
87 views

Angle the Sun makes with the horizon during sunset

Let's say it is the day of the summer solstice and the Sun is setting at 23.5 degrees declination. I am at let's say, 10 degrees latitude. How would I go about calculating the angle of the Sun below ...
2
votes
0answers
26 views

Explain as simply as possible how the Sunyaev-Zeldovich (SZ) effect is used to estimate the Hubble constant

The Sunyaev–Zeldovich effect (SZ effect) is useful in determining the Hubble constant because it is independent of the cosmic distance ladder. This effect occurs when CMB (cosmic microwave background) ...
1
vote
1answer
83 views

When thermal infrared space telescopes spot asteroids, are they seeing the body's own thermal emission, or reflected TIR from the Sun?

From the Space SE question Why has the Earth-Sun libration point L1 been chosen over L2 for NEOCam to detect new NEOs?: above: Profoundly not-to-scale illustration of NEOCam in an orbit around the ...
2
votes
1answer
60 views

How do the stars in the near-infrared (NIR) radiate?

Let's say we are studying the integrated near-infrared (NIR) light of a distant spiral galaxy. We would expect most of this light to be dominated by red giants stars and dwarfs. I assumed these stars ...
1
vote
0answers
47 views

Which version of Stellarium made you fly from one moon to another?

I recall a version of Stellarium (it was the very first time I had Stellarium) many years ago that made you fly between moons of the same system if you changed celestial bodies. E.g. if you were on ...
5
votes
3answers
215 views

How can there only be “11 phonons” in the mirrors of LIGO interferometers?

LIGO is an incredibly sensitive detector of small changes in space due to the passing of gravitational waves and uses some very high-level mathematics and physics and experimental techniques to drive ...
2
votes
1answer
69 views

How did the measured diameter of Ceres evolve over time?

Based on the Wikipedia page of Ceres, Herschel measured a diameter of 260 kilometers for Ceres, and Schröter measured 2613 kilometers. I do remember seeing at least a half-dozen estimates of the ...
1
vote
1answer
52 views

Comoving Volume Calculation

Suppose I have data from an astronomical survey at redshifts in the range $z = [2,3]$. Suppose that, on average in this range, the data covers an area on the sky of $A=1$ $\mathrm{Mpc}^2$. How would I ...
2
votes
1answer
71 views

Lightest object so far to function as gravitational lense?

Many amazing discovers are based on gravitational lensing and microlensing, but as non-expert it is not obvious to me: What is the (current) lower mass limit of the lensing object(s) for which ...
1
vote
1answer
75 views

Is the mass of antimatter negative or positive? [closed]

Is the mass of antimatter negative or positive For example, the mass of the electron 9.1×10^(-31), does this mean that the mass of the positron -9.1×10^(-31)?
1
vote
1answer
45 views

Derive LOSVD from galaxy spectrum, using fourier method

I am trying to implement a programm, that derives the kinematics (specifically the kinematic parameters: mean rotation velocity, velocity, dispersion, hermite coefficients h3 and h4) from an ...
1
vote
1answer
35 views

What is Lawrence Krause's theory of total energies?

Does Lawrence Krauss theory say that the total energy in the universe is equal to zero or that the energy in the entire universe remains constant and the mass in the entire universe also remains ...

1
2 3 4 5
18