Rosette Nebula – NGC 2237 – Caldwell 49

By way of introduction to the Rosette Nebula

In this article, I have gathered in one place the most interesting information about the entire nebula and its selected regions. The information contained in this content is my own compilation based on collected data.

About the Nebula Itself
The Rosette Nebula (also known as Caldwell 49) is an H II region (ionized hydrogen) located near one end of a giant molecular cloud in Monoceros, a region of the Milky Way.

Rosette Nebula – NGC 2237 – Caldwell 49

It has been observed that the nebula has a shape resembling a human skull and is sometimes called the “Skull Nebula.” It should not be confused with the object designated as NGC 246, which is also called the “Skull Nebula.”

Nebula Location

Firmament – Coordinates for the nebula’s reference position (Equatorial (J2000)):

• RA, Dec: 06h30m54.6143s, +05d02m57.008s
• RA, Dec [Deg]: 97.727560, 5.049169

The nebular complex has the following New General Catalogue (NGC) designations:

• NGC 2237 – Part of the nebular region (also used to refer to the entire nebula)
• NGC 2238 – Part of the nebular region
• NGC 2239 – Part of the nebular region (Discovered by John Herschel)
• NGC 2244 – Open cluster within the nebula (Discovered by John Flamsteed in 1690)
• NGC 2246 – Part of the nebular region

NGC 2237 Region – Part of the Rosette Nebula

• Type: Emission nebula (part of the Rosette Nebula)
• Distance: Approximately 5,000–5,200 light-years from Earth
• Size: The entire Rosette Nebula has a diameter of about 130 light-years
• Structure: Contains ionized hydrogen gas, which glows due to radiation from nearby young stars

Below is the highlighted entire area encompassing the regions:

• NGC2237
• NGC2238
• NGC2239
• NGC2246

Regions: NGC2237 NGC2238 NGC2239 NGC2246

The Role of the Nebula in the Star Formation Process

Observations and Scientific Significance

• X-ray studies (e.g., using the Chandra X-ray Observatory) have revealed numerous young stars embedded in the nebula.
• Infrared observations help detect hidden protostars still forming within dense molecular clouds.
• The nebula’s mass is estimated at around 10,000 solar masses, making it an important object for studying stellar evolution and nebular dynamics.

Compared to other H II regions like the Orion Nebula (M42) and Lagoon Nebula (M8), NGC 2238 is less intensively studied but remains an interesting site for star formation. In terms of brightness, NGC 2238 has an apparent magnitude of about 6, meaning it is visible through small telescopes and binoculars. Regarding size, NGC 2238 is part of the larger Rosette Nebula complex, which has a diameter of approximately 130 light-years.

Star Formation in NGC 2238
Within the Rosette Nebula, including NGC 2238, young, hot stars have formed from nebular material approximately 4 million years ago. These stars emit intense ultraviolet radiation, ionizing the nebular gas and causing it to glow. Additionally, stellar winds from these young stars have blown out the central region of the nebula, creating a distinct cavity surrounded by gas and dust layers—a phenomenon typical of H II regions, where massive stars shape the surrounding material.

Structure and Observations
NGC 2238, like other parts of the Rosette Nebula, is an emission nebula, meaning its gas glows due to ionization from nearby stars.

Methods for Observing NGC 2238

1. Visual Observations

• Binoculars: Even a small pair of 50mm binoculars can reveal fragments of the nebula in a dark sky.
• Telescopes: To observe larger structures, low magnifications (20–50x) and wide-angle eyepieces are recommended.
• Filters: UHC or OIII filters enhance nebular contrast and structure.

2. Astronomical Photography

• CCD cameras: Used to capture the nebula in different wavelengths, including H-alpha, which reveals gas details.
• Long exposures: Since the nebula is relatively faint, long exposure times and precise telescope tracking are required.
• Narrowband filters: H-alpha and SII filters improve nebular detail by isolating specific wavelengths.

3. Infrared Observations

• Space telescopes: Infrared studies, using NASA’s Spitzer Space Telescope, allow researchers to examine structures hidden within nebular dust clouds.
• Night vision devices: Some nebulae, including NGC 2238, can be observed using H-alpha filters on night vision equipment.

NGC 2239 Region

NGC 2239 is visible from both hemispheres at certain times of the year and has an apparent magnitude of approximately 4.8, making it barely visible to the naked eye but easily observable with binoculars. It lies around 5,000 light-years from Earth and has a diameter of approximately 130 light-years—a fascinating region of space that remains an active birthplace of stars!

Object Coordinates – J2000
Right Ascension: 06h 31m 55s
Declination: +04° 56’ 34”

NGC 2246 Region

The Role of H II Regions in Galaxy Evolution

Specific Star Formation Processes in H II Regions like NGC 2246

• H II regions originate from giant molecular clouds (GMCs) made primarily of cold molecular hydrogen (H₂).
• Density fluctuations within these clouds can lead to gravitational collapse, forming dense cores, the precursors to protostars.

2. Triggered Star Formation

• Young, massive stars emit intense UV radiation and powerful stellar winds.
• This UV radiation ionizes the surrounding gas, creating hot (≈10,000 K) ionized H II regions.
• Expanding shock waves compress dense gas pockets, triggering new protostar formation.
• Dark structures like elephant trunks and Bok globules resist ionization, allowing stars to form within.

3. Internal Processes in Collapsing Cores

• Fragmentation of the cloud leads to dense cores.
• Accretion feeds protostars, which shine in infrared wavelengths.
• Protoplanetary disks and jets emerge, shaping stellar environments.
• Once nuclear fusion begins, a protostar enters the main sequence phase.

Observations of NGC 2246 confirm active star formation. Dark collapsing globules, intense X-ray emissions from newborn stars (Chandra X-ray Observatory), and young star clusters like NGC 2244 illustrate the ongoing stellar birth.

NGC 2244 Star Cluster (Caldwell 50)

The open cluster at the heart of the Rosette Nebula, also called Caldwell 50, is a young star cluster in the Monoceros constellation.

• Stars in NGC 2244 formed from Rosette Nebula material several million years ago.
• Their UV radiation ionizes hydrogen gas, illuminating the nebula.
• Stellar winds from these stars create a central cavity, pushing gas outward.

Region: NGC2244

Key Features of the Cluster

• Distance: Approximately 5,200 light-years from Earth
• Age: Less than 5 million years
• Size: The cluster has a radius of about 18 light-years
• Brightness: Apparent magnitude 4.8, making it visible through binoculars

Most Notable Stars

• HD 46223: A massive, extremely hot O4V-type star, about 400,000 times brighter than the Sun and 50 times more massive. One of the most energetic stars in the region.
  • Surface Temperature: Around 40,000 K (Kelvin)
• HD 46150: An O5V-type star, 450,000 times brighter than the Sun with a mass of up to 60 times that of the Sun.

These stars emit intense radiation and stellar winds, which shape the surrounding nebula.

Stars: HD46223, HD46150

The Significance of NGC 2244 in Astronomy

NGC 2244 holds great importance in astronomy due to its role in stellar formation processes and its interaction with the surrounding Rosette Nebula. Here’s why astronomers study this cluster:

• Young, massive stars: NGC 2244 contains hot, massive O-type stars, some of the brightest and most energetic stars in the universe. They emit intense ultraviolet radiation, which ionizes the surrounding hydrogen gas, making the Rosette Nebula glow.
• Impact on the surrounding nebula: The strong stellar winds from stars in NGC 2244 push gas and dust away, creating the central cavity in the Rosette Nebula. This process helps astronomers understand how massive stars shape their surroundings and influence future star formation.
• Studies of stellar formation: Since NGC 2244 is a relatively young cluster (less than 5 million years old), it is an ideal target for studying the early stages of stellar evolution. Observations of this cluster help scientists understand how stars form, evolve, and interact.
• X-ray and infrared observations: Astronomers use telescopes like Chandra X-ray Observatory and Spitzer Space Telescope to study the cluster in X-ray and infrared wavelengths. These observations reveal hidden young stars still embedded in gas and dust, providing valuable insights into stellar birth.
• A window into galaxy evolution: Because NGC 2244 is part of a larger H II region (ionized hydrogen cloud), studying it helps astronomers understand how similar nebulae contribute to chemical enrichment and galaxy evolution.

How Do Astronomers Observe NGC 2244 Using Different Telescopes?

Astronomers study NGC 2244 and the Rosette Nebula using various telescopes that observe different parts of the electromagnetic spectrum. Each type of observation provides unique information about the cluster’s structure, composition, and ongoing processes.

1. Optical Observations – Telescopes like the Hubble Space Telescope (HST) and ground-based observatories capture visible light emitted by stars and ionized gas in the nebula, helping map the cluster’s structure, star distribution, and brightness.

Examples of telescopes:

• Hubble Space Telescope (HST)
• Very Large Telescope (VLT) – ESO
• Keck Observatory

2. Infrared Observations – Infrared telescopes like the Spitzer Space Telescope and James Webb Space Telescope (JWST) allow astronomers to detect young stars hidden within gas and dust clouds. Infrared wavelengths penetrate dust clouds, revealing ongoing star formation.

Examples of telescopes:

• Spitzer Space Telescope (NASA)
• James Webb Space Telescope (JWST)
• Infrared Astronomical Satellite (IRAS)

3. Obserwacje w promieniowaniu rentgenowskim – Chandra X-ray Observatory bada wysokoenergetyczne promieniowanie rentgenowskie emitowane przez gorące, młode gwiazdy w NGC 2244.
Pomaga w identyfikacji gwiazd neutronowych, czarnych dziur oraz procesów związanych z silnymi wiatrami gwiazdowymi.

Przykłady teleskopów:
Chandra X-ray Observatory (NASA)
XMM-Newton (ESA)

4. Obserwacje radiowe – Radioteleskopy, takie jak ALMA i VLA, badają chłodne obłoki gazu i pyłu, które mogą być miejscem narodzin nowych gwiazd.

Przykłady teleskopów:
Atacama Large Millimeter/submillimeter Array (ALMA)
Very Large Array (VLA)
Green Bank Telescope (GBT)

Dlaczego używa się różnych teleskopów?
Każdy zakres promieniowania elektromagnetycznego dostarcza unikalnych informacji o NGC 2244 i Mgławicy Rozeta:

• Światło widzialne → Struktura mgławicy i rozmieszczenie gwiazd.
• Podczerwień → Ukryte młode gwiazdy i procesy formowania.
• Rentgen → Gorące, masywne gwiazdy i ich wpływ na otoczenie.
• Radio → Chłodne obłoki gazu i pyłu, z których powstają nowe gwiazdy.

Pomagają w analizie składu chemicznego mgławicy oraz dynamiki gazu.

Podsumowanie

Mgławica Rozeta dostarcza cennych informacji o procesach ewolucji gwiazd i wpływie masywnych gwiazd na swoje otoczenie, co czyni ją jednym z najważniejszych obiektów badań w astrofizyce.

Bibliografia:
https://en.wikipedia.org/wiki/Rosette_Nebula
https://www.nasa.gov/image-article/rosette-nebula/
http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+2237
https://theskylive.com/sky/deepsky/ngc2239-object
https://theskylive.com/sky/deepsky/ngc2246-rosette-b-object

http://cdsportal.u-strasbg.fr/?target=NGC%202238%20
http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC%202238
http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+2237
https://ned.ipac.caltech.edu/cgi-bin/objsearch?extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES&objname=NGC%202238
https://pl.wikipedia.org/wiki/NGC_246